Gallium

What is Gallium?

Gallium nitrate holds FDA application NDA 019961, approved January 17, 1991 as a Type 1 new molecular entity on priority review with orphan designation. That approval covers one route: a concentrate diluted into a liter of 0.9 percent sodium chloride or 5 percent dextrose and infused into a vein over 24 hours, for five days, to bring down the blood calcium of a cancer patient who has already failed hydration.

Gallium is element 31, standard atomic weight 69.723, a soft silvery metal that melts at 29.7646 degrees Celsius (85.576 degrees Fahrenheit) and will liquefy in a warm palm. Paul-Emile Lecoq de Boisbaudran isolated it in 1875, filling the gap Dmitri Mendeleev had predicted in 1871 and provisionally named eka-aluminum. It forms no ore of its own; the US Geological Survey puts the average gallium content of bauxite at 50 parts per million.

What makes gallium medically interesting is a coincidence of ionic geometry. The octahedral ionic radius of Ga3+ is 0.620 angstroms against 0.645 angstroms for high spin Fe3+. Transferrin, the iron transport protein in blood, binds gallium at its two metal sites with association constants of log K1 = 20.3 and log K2 = 19.3, close enough to iron's log K1 = 22.8 and log K2 = 21.7 that the body routes gallium through the iron system by mistake. The critical difference is that Ga3+ cannot drop to a divalent state under physiological conditions. It occupies iron's chairs and does none of iron's work. Every therapeutic and diagnostic use of gallium descends from that fact.

Common Names

Gallium, Ga, element 31, eka-aluminum. Pharmaceutical names include Ganite (gallium nitrate injection), gallium citrate Ga 67, gallium Ga 68 dotatate (NETSPOT), and gallium Ga 68 gozetotide, the USAN for the agent published as Ga-68 PSMA-11 and sold as Locametz, Illuccix and Gozellix. Consumer-facing names include "colloidal gallium," "trace gallium," and gallium maltolate relabeled as a dietary supplement.

Primary Active Compounds

• Gallium nitrate, anhydrous GaN3O9, molecular weight 255.74. The injectable is labeled as the nonahydrate, molecular weight 417.87, at 25 mg per mL with 28.75 mg sodium citrate dihydrate per mL, pH 6.0 to 7.0.

• Gallium maltolate, tris(3-hydroxy-2-methyl-4H-pyran-4-onato)gallium, C18H15GaO9, molecular weight 445.0, CAS 108560-70-9. Gallium is 15.7 percent of that mass, so the 500 mg research dose studied in trials delivers 78.4 mg of elemental gallium. That is a quantity used in clinical studies, not an amount to take.

• Gallium citrate, carrier for the Ga-67 diagnostic agent and for the inhaled investigational drug AR-501.

• Gallium arsenide, AsGa, molecular weight 144.645, CAS 1303-00-0, the semiconductor compound and an IARC Group 1 human carcinogen.

Key Note

Gallium has no Reference Daily Intake and no Daily Value. FDA's dietary supplement labeling guidance lists fourteen minerals with Daily Values: calcium, iron, phosphorus, iodine, magnesium, zinc, selenium, copper, manganese, chromium, molybdenum, chloride, sodium and potassium. Gallium is not among them, so any Supplement Facts panel declaring it must carry a symbol referring to the footnote "Daily Value Not Established." The European Food Safety Authority completed its dietary reference value program in 2019 across 34 opinions and set no value for gallium either.

Primary Functions & Benefits

Gallium has no function in human physiology, and the reason is worth stating precisely rather than as a slogan. Iron works in biology because it cycles between Fe2+ and Fe3+, donating and accepting electrons in cytochromes, in iron-sulfur clusters, and at the tyrosyl radical site of ribonucleotide reductase. Gallium enters the same protein pockets and can do none of that chemistry, because Ga3+ has no accessible divalent state at physiological potentials. It is a structural impostor with no catalytic capacity.

That inertness is what medicine exploits. Christopher Chitambar's 2016 review in Biochimica et Biophysica Acta, volume 1863, pages 2044 to 2053, describes a two-step mechanism: transferrin-bound gallium is taken up preferentially by cells expressing high levels of transferrin receptor 1, which includes lymphoma, urothelial carcinoma and breast cancer cells, and once inside, gallium disrupts iron-dependent processes rather than participating in them. Three effects follow, all documented in humans: inhibition of osteoclastic bone resorption, which lowers pathologically elevated serum calcium; inhibition of DNA synthesis through the R2 subunit of ribonucleotide reductase; and disruption of bacterial iron acquisition.

None of these are functions gallium performs for you. They are interferences, useful only under specific clinical conditions.

Forms & Standardization

For gallium this section is the pharmacology and toxicology of each chemical form, because ligand and route determine almost everything the element does. Two gallium compounds with identical gallium content behave nothing alike.

Gallium nitrate, intravenous

The reference form. Kelsen and colleagues reported in Cancer, 1980, volume 46, pages 2009 to 2013, that continuous infusion at 200 mg/m2 produced steady state plasma gallium of 0.9 to 1.9 micrograms per mL, with 68 to 107 percent of the dose recovered in urine. After rapid infusion the curve is biphasic, with a distribution half life of 8.3 to 26 minutes and a terminal half life spanning 6.3 to 196 hours. Average plasma clearance on the approved label is 0.15 L/hr/kg, with no hepatic or renal metabolism. The drug leaves essentially intact through the kidney, which is why the kidney is the organ at risk.

Gallium nitrate, oral

Poorly absorbed, and this is the central pharmacological fact behind every oral gallium product on the consumer market. Chitambar's 2012 review in Future Medicinal Chemistry, volume 4, pages 1257 to 1272, states that oral gallium nitrate bioavailability is poor, restricting the salt to the intravenous route. Emisphere built an absorption-enhanced tablet, G4544, precisely because the plain salt does not work by mouth.

Gallium maltolate, oral

The one oral form with real human pharmacokinetic data, published by Bernstein, Tanner, Godfrey and Noll in Metal-Based Drugs, 2000, volume 7, pages 33 to 47. The compound is moderately water soluble at 10.7 mg/mL at 25 degrees Celsius, with an octanol partition coefficient of 0.41, and is electrically neutral between pH 5.5 and 8.0. Twelve healthy volunteers, three per dose, received single oral doses of 100, 200, 300 or 500 mg. Absorption half life was 0.8 to 2.0 hours, central compartment excretion half life 17 to 21 hours, estimated oral bioavailability 25 to 57 percent, and peak serum gallium 0.115 micrograms per mL at 100 mg rising to 0.569 micrograms per mL at 500 mg.

The most telling number in that paper is the urinary one. About 2 percent of an oral gallium maltolate dose appeared in urine over 72 hours, against 49 to 94 percent within 24 hours after intravenous gallium nitrate. The authors read this as nearly all orally absorbed gallium binding to transferrin, while intravenous nitrate overshoots transferrin capacity and circulates as free gallate, Ga(OH)4 minus, which the kidney dumps.

Gallium chloride and gallium citrate

Chitambar's 2012 review reports, citing Collery, that oral gallium chloride was tested in clinical trials at 100 to 1400 mg per 24 hours, producing partial responses in ovarian cancer but not lung cancer, with development stalling on low bioavailability; in rats on prolonged oral dosing, gallium accumulated preferentially in bone and lung. Gallium citrate is the carrier for radiolabeled diagnostics and for AR-501, the investigational inhaled antibiotic developed by Aridis as Panaecin. The Ga-67 citrate label specifies 8.3 nanograms of gallium chloride Ga 67 per mL and states that no carrier has been added, so the diagnostic product is essentially carrier-free and the entire clinical effect is radiological.

Gallium arsenide

Not a medicine in any form. AsGa is the compound semiconductor used in laser diodes, LEDs, photodetectors and radio frequency integrated circuits. IARC classified it Group 1, carcinogenic to humans, in Monographs Volume 86 (2006). It belongs here because it is the form in which most of the world's gallium exists as a manufactured material.

Metallic gallium and KP46

Elemental gallium is not meaningfully absorbed and is generally described as non-toxic to handle, though it embrittles aluminum along grain boundaries. The oral investigational complex KP46, tris(8-quinolinolato)gallium(III), has a mouse oral LD50 of 2870 mg/kg in males and 2370 mg/kg in females, and reached phase 1/2 in solid tumors without advancing further.

No USP monograph governs gallium as a dietary ingredient and no compendial assay defines purity for an oral gallium product.

Food Sources

Gallium is not a food component in any nutritionally meaningful sense, so this section covers the three real routes by which gallium enters a human body.

Diet

Gallium appears in the food supply at the edge of detection, and mostly below it. Millour and colleagues measured 28 minerals and trace elements across 1,319 food samples in the Second French Total Diet Study (Journal of Food Composition and Analysis, 2012, volume 25, pages 108 to 129). For gallium, 99.5 percent of samples fell below the limit of detection or the limit of quantification, which was 0.002 mg/kg; only 7 samples could be quantified at all. The highest mean concentration was in butter at roughly 15 micrograms per kilogram, then chocolate at 1.0 to 1.9 micrograms per kilogram, with every other food group under 1.0 microgram per kilogram on the lower-bound estimate. Butter was accordingly the main contributor to French dietary gallium exposure, 73 percent in adults and 70 percent in children. A full kilogram of butter, the richest food measured, would supply about 15 micrograms. The 500 mg gallium maltolate dose used in trials delivers 78.4 mg of elemental gallium, on the order of 5,000 times as much.

Occupational exposure

The largest non-medical exposure route, and it is inhalation rather than diet. Chen measured gallium in inhalable air and in worker urine at Taiwanese semiconductor plants, reported in Bulletin of Environmental Contamination and Toxicology, 2007, volume 78, pages 123 to 127, and found both air and urinary gallium substantially higher in production operators and engineers than in office administrators at the same companies.

Medical administration

The only route delivering a pharmacologically active quantity. A 1.7 square meter adult on the approved Ganite regimen receives about 340 mg of gallium nitrate daily for five days, roughly 1,700 mg total, into a vein. Diagnostic agents deliver radioactivity rather than mass. Food is not a source of gallium in any amount that matters, and the only reason to know the dietary number is to see how large a pharmaceutical dose really is.

Who Should Take Gallium

No one should take gallium as a supplement. There is no deficiency to correct, no oral product reviewed for safety or efficacy, and no dosing framework outside a hospital. What follows describes who receives gallium under medical supervision, and in what setting.

Patients with cancer-related hypercalcemia

The population named on the Ganite label: adults with clearly symptomatic cancer-related hypercalcemia unresponsive to adequate hydration, typically with albumin-corrected serum calcium above 12 mg/dL. Administration requires an infusion pump, a 24-hour line, daily serum creatinine monitoring, and a supervised infusion setting. In practice the indication has been absorbed by intravenous bisphosphonates and denosumab, and the gallium product has not been commercially available in the United States for well over a decade.

Patients undergoing diagnostic imaging

The largest group receiving gallium today, and they receive it as a radiotracer. Ga-67 citrate, NDA 017478 with an original approval of May 17, 1976, covered Hodgkin disease, lymphomas and bronchogenic carcinoma before FDG PET displaced it. NETSPOT, NDA 208547, was approved June 1, 2016 for somatostatin receptor positive neuroendocrine tumors in adults and children. Gallium Ga 68 PSMA-11 was approved December 1, 2020 under two simultaneous academic applications, NDA 212642 held by UCLA and NDA 212643 held by UCSF, with commercial kits following as Illuccix, Locametz and Gozellix, and generics in 2026.

Clinical trial participants

The active programs: the phase 1 oral gallium maltolate trial in recurrent glioblastoma at the Medical College of Wisconsin, the GABRIEL pediatric trial in relapsed high-grade glioma, the ABATE study of intravenous gallium in cystic fibrosis patients with nontuberculous mycobacteria (NCT04294043), and the inhaled gallium citrate program AR-501.

Who Should AVOID or Use Caution

Contraindications

• Anyone considering gallium as a dietary supplement. There is no indication, no established oral dose outside a trial protocol, and no reviewed product.

• Severe renal impairment. The Ganite label contraindicates administration when serum creatinine exceeds 2.5 mg/dL and directs discontinuation if creatinine crosses that threshold during treatment.

• Concurrent administration with other potentially nephrotoxic drugs. The boxed warning names aminoglycosides and amphotericin B specifically. If such a drug becomes necessary, the label directs stopping gallium nitrate and continuing hydration for several days afterward.

Use Caution

• Patients with compromised cardiovascular status, because the hydration protocol that protects the kidney risks overhydration. The label targets urine output near 2 L per day.

• Patients with baseline hypocalcemia, given that hypocalcemia occurred in about 38 percent of patients on the approved regimen.

• Anyone with a preexisting optic nerve disorder. Reversible optic neuropathy was the dose-limiting toxicity in the bladder cancer program, appearing in 3 of 11 patients at 400 mg/m2 per day.

• Semiconductor fabrication and wafer polishing workers, whose exposure is to gallium arsenide, a Group 1 carcinogen. IARC attributes the risk to two mechanisms rather than one: arsenic released from the compound behaving as inorganic arsenic, and the gallium moiety itself, which the working group thought might account for the lung tumors seen in female rats.

Critical Safety Point

The kidney is where gallium concentrates the damage. Newman, Brody and Krakoff showed in Cancer, 1979, volume 44, pages 1728 to 1740, that gallium nitrate in rats produces renal precipitates occluding tubular lumina, identified by x-ray energy spectrometry as gallium complexed with calcium and phosphate. Pretreatment with the osmotic diuretic isosorbide reduced both the precipitates and the histopathology, by diluting gallium and calcium in tubular fluid rather than by altering pharmacokinetics. That is the mechanistic reason the human label is built around hydration, urine output and serial creatinine. An oral product taken at home has none of those guardrails.

Recommended Dosages

There is no supplemental dose of gallium, because gallium is not a nutrient and no oral gallium product has an approved indication. Every number below is a clinical or regulatory fact about a specific product in a specific setting. None is an amount to consume.

Approved therapeutic dosing, gallium nitrate injection

• 200 mg/m2 daily, diluted in 1,000 mL of 0.9 percent sodium chloride or 5 percent dextrose, infused continuously over 24 hours, for five consecutive days.

• 100 mg/m2 daily for five days is the labeled alternative for mild hypercalcemia with fewer symptoms.

Investigational oncology dosing, historical

• 300 mg/m2 daily by seven-day continuous infusion in advanced malignant lymphoma (Warrell and colleagues, Cancer, 1983, volume 51, pages 1982 to 1987).

• 350 mg/m2 daily or more by five-day continuous infusion in refractory urothelial tumors, with 400 mg/m2 as the toxicity ceiling (Seidman and colleagues, Cancer, 1991, volume 68, pages 2561 to 2565).

Investigational oral dosing, gallium maltolate

The phase 1 recurrent glioblastoma trial by Connelly and colleagues, published in Neuro-Oncology Advances on June 8, 2026, volume 8, article vdag154, used a 3+3 escalation across five levels from 500 to 2,500 mg daily in 24 patients. The recommended phase 2 dose was 2,000 mg per day, set by diarrhea requiring treatment and by serum gallium plateauing between 2,000 and 2,500 mg daily. That is a research dose established in patients with a terminal brain tumor under close monitoring.

Diagnostic dosing

• Gallium citrate Ga 67: 74 to 185 MBq (2 to 5 mCi) for a 70 kg adult.

• NETSPOT: 2 MBq/kg to a maximum of 200 MBq (5.4 mCi), in adults and children.

• Gallium Ga 68 PSMA-11: 111 to 259 MBq (3 to 7 mCi).

Regulatory ceilings, occupational

These airborne limits are the only numerical exposure ceilings reaching gallium workers, and both are set on the arsenic in gallium arsenide rather than on gallium itself.

• OSHA PEL through the inorganic arsenic standard at 29 CFR 1910.1018: 0.01 mg/m3 as arsenic, 8-hour TWA, with a 5 micrograms per cubic meter action level.

• NIOSH REL for inorganic arsenic: 0.002 mg/m3 ceiling over 15 minutes.

Duration

The approved therapeutic course is five days and no longer. Paget disease work used two 14-day subcutaneous cycles at 0.05, 0.25 or 0.5 mg/kg per day (Bockman and colleagues, Journal of Clinical Endocrinology and Metabolism, 1995, volume 80, pages 595 to 602). The glioblastoma trial ran in 4-week cycles, with one patient still on treatment after 33 cycles at publication. No approved gallium regimen is chronic, and there is no evidence base for indefinite daily oral use.

Timing & Administration

Administration detail for gallium is entirely hospital protocol, and the specificity of that protocol is itself informative. Gallium nitrate concentrate must be diluted into 1,000 mL of 0.9 percent sodium chloride or 5 percent dextrose. The diluted solution is stable 48 hours at 15 to 30 degrees Celsius or 7 days refrigerated at 2 to 8 degrees Celsius. Infusion runs continuously over a full 24 hours, not as a bolus, because the bolus schedule tried first produced high peak plasma levels and dose-limiting nephrotoxicity. Hydration comes before the drug: the label directs establishing adequate hydration with fluid, preferably saline, before starting, targeting urine output near 2 L per day throughout, avoiding diuretics until low blood volume is corrected, and checking serum creatinine at baseline and through the course.

Imaging agents run on clocks set by isotope physics. Ga-67 has a physical half life of 78.3 hours, so scanning is typically done about 48 hours after injection. Ga-68 has a half life of 67.71 minutes, which the labels round to 68 minutes, and is commonly eluted on site from a germanium-68 generator whose parent has a half life of 270.93 days; NETSPOT images are acquired 40 to 90 minutes post-injection. That clock is why most of these products are supplied as kits and radiolabeled in the imaging department the hour they are used, though a few ready-to-use Ga-68 solutions are now produced centrally and shipped as unit doses.

Timeline of Effects

Hypercalcemia

The effect builds over the course of treatment, not on day one. Against etidronate, median duration of normocalcemia was 8 days for gallium against 0 days (p = 0.0005); against calcitonin, 6 days against 1 day (p less than 0.001).

Bone turnover in Paget disease

Slower. In the 49-patient multicenter trial, serum alkaline phosphatase fell 24 percent at 0.25 mg/kg per day and 31 percent at 0.5 mg/kg per day by week 12, from a group mean baseline of 854 IU/L. Urinary hydroxyproline reached its nadir at 10 weeks.

Antitumor response

Median duration of response was 2.5 months in the lymphoma trial and 4 months (range 2 to 8 months) in the bladder cancer trial. In the glioblastoma phase 1, disease progressed in 11 of 22 evaluable patients after two cycles and in another 6 after three to six cycles, with median overall survival of 16 months.

Antibacterial effect

In the phase 1 cystic fibrosis component reported by Goss and colleagues in Science Translational Medicine, 2018, volume 10, article eaat7520, systemic gallium improved lung function in people with chronic Pseudomonas aeruginosa infection. The follow-on phase 2 IGNITE study (NCT02354859) randomized 119 participants to a five-day infusion at 200 mg/m2 per day or saline placebo. At day 28, 22 of 60 in the gallium arm and 17 of 56 in the placebo arm reached a 5 percent or greater relative increase in FEV1: a difference of 5.9 percent, 95 percent CI minus 11.2 to 22.4 percent, p = 0.811. The trial missed its primary endpoint, and it is a fair example of a phase 1 signal not carrying into phase 2.

Benefits of Taking Gallium

There are no benefits to taking gallium as a supplement and nothing in the literature supports the practice. What follows are the documented clinical uses, described as clinical uses.

Hypercalcemia of malignancy

The best-supported use and the only approved one, resting on two randomized double-blind trials by Warrell and colleagues, the first at Memorial Sloan Kettering and the second multicenter. In Annals of Internal Medicine, 1988, volume 108, pages 669 to 674, 50 patients received gallium nitrate 200 mg/m2 by continuous infusion or salmon calcitonin 8 IU/kg intramuscularly every six hours, both for five days, with sham injections and infusions preserving the blind. Eighteen of 24 on gallium reached normocalcemia against 8 of 26 on calcitonin, a 44 percent absolute difference (95 percent CI 19 to 69 percent, p = 0.002). In the Journal of Clinical Oncology, 1991, volume 9, pages 1467 to 1475, 71 patients received gallium nitrate 200 mg/m2 daily or etidronate 7.5 mg/kg, both for five days: 28 of 34 on gallium (82 percent) reached normocalcemia against 16 of 37 on etidronate (43 percent), p less than 0.001.

Lymphoma and bladder cancer

Real but historical. Chitambar's 2010 review in the International Journal of Environmental Research and Public Health, volume 7, pages 2337 to 2361, summarizes at least four single-agent trials as showing roughly 30 percent of patients with relapsed non-Hodgkin lymphoma responding; that figure is the review's narrative estimate rather than a pooled result with a stated denominator. The individual trials are firmer: in the seven-day infusion study, 16 of 47 evaluable patients (34 percent) achieved major responses. In refractory urothelial cancer, 4 of 23 patients (17.4 percent) receiving 350 mg/m2 per day or more achieved partial responses, with none among 17 patients below that dose. Myelosuppression was minimal in both of those trials, which is why the reviews describe gallium nitrate as sparing white cells and platelets and usable in patients with low counts.

Paget disease, antimicrobial activity, glioblastoma

Positive pilot data in Paget disease, never carried to approval. Goss and colleagues showed micromolar gallium inhibited P. aeruginosa growth in cystic fibrosis sputum and that resistance developed slowly. In glioblastoma, phase 1 only.

What the evidence does not show, at any dose or route: that gallium improves energy, immunity, cognition, longevity, bone density in healthy people, or any general wellness endpoint. No trial has tested such a claim.

Potential Negatives & Side Effects

From the approved intravenous product

• Hypocalcemia in about 38 percent of patients, generally mild, with albumin-corrected calcium falling to the 6.5 to 8.0 mg/dL range.

• Transient hypophosphatemia in up to 79 percent, sometimes requiring oral phosphorus supplementation.

• Renal dysfunction, defined as elevated BUN or creatinine, in 12.5 percent. Two patients in the trial program developed acute renal failure.

• Acute optic neuritis in under 1 percent at high doses, with one reported case of permanent blindness. Csaky and Caruso described a 77-year-old man in the American Journal of Ophthalmology, 1997, volume 124, pages 567 to 568, with bilateral visual loss, central scotomas and reduced P2-wave amplitude, who partially recovered after 12 months of oral ferrous sulfate.

• Microcytic anemia consistent with functional iron deprivation. This one belongs to the higher-dose and investigational settings rather than the approved regimen: the label attaches anemia to very high doses of up to 1,400 mg/m2, and the supporting human evidence comes from Seligman and colleagues in the American Journal of Hematology, 1992, volume 41, pages 232 to 240, where seven patients completing two courses of constant-infusion gallium nitrate all developed hypochromic microcytic anemia with a mean 3.3-fold rise in red cell zinc protoporphyrin.

From oral gallium maltolate

In the 24-patient glioblastoma phase 1, grade 1 or 2 diarrhea, anorexia, nausea and fatigue occurred in all 24 patients. ALT elevation occurred in one patient each at 1,000 and 2,000 mg per day. Red cell mean corpuscular volume fell below normal during treatment in 9 patients, again pointing at functional iron restriction. Nephrotoxicity was not seen at these oral doses.

That MCV finding deserves emphasis. Gallium works by starving cells of usable iron. In a glioblastoma patient that is the therapeutic intent. In a healthy person it is a side effect with no offsetting benefit, and healthy people are precisely who buys the powder.

Deficiency Symptoms

There is no gallium deficiency state and there cannot be one, because no human protein, enzyme or pathway requires gallium. A deficiency is defined by a function that fails when the element is absent, and gallium has no function to fail.

The contrast with a genuine trace element is instructive, and iron is the sharpest available because gallium spends its entire biological career impersonating it. Iron carries an RDA of 8 mg per day for adult men and 18 mg per day for women aged 19 to 50, set by the Institute of Medicine in 2001, and its deficiency produces a specific, measurable syndrome: microcytic hypochromic anemia, fatigue, impaired work capacity, and in children impaired cognitive development.

Gallium has none of that, and the absence is not a gap in the research. No agency has set an EAR, an RDA, an AI or a UL for it. The Institute of Medicine's 2001 DRI volume went as far as reviewing arsenic, boron, nickel, silicon and vanadium, elements with suggestive but unestablished roles, and declined to set requirements for any. Gallium did not reach that list.

What gallium addresses

Nothing nutritional. Under medical supervision, gallium nitrate addresses pathologically elevated serum calcium caused by cancer. Radioactive gallium addresses a diagnostic question. Investigational gallium compounds address tumor iron dependence and bacterial iron acquisition. These are interventions in disease, not corrections of a shortfall.

Bottom line

A gallium supplement cannot fix a deficiency, because the deficiency does not exist. If a product implies otherwise, that claim has no scientific referent at all.

Toxicity Symptoms

At high intake

Gallium toxicity in humans is essentially renal, driven by dose and route. The rapid bolus schedule of 700 mg/m2 over 15 to 30 minutes was abandoned specifically because it produced dose-limiting kidney injury, through intratubular precipitation of gallium with calcium and phosphate alongside hypercalciuria. The practical threshold on the approved label is a serum creatinine of 2.5 mg/dL.

Gallium also inhibits heme synthesis. Goering and Rehm showed that a single intraperitoneal dose of soluble gallium sulfate at 12.5 to 200 mg Ga per kg produced dose-dependent noncompetitive inhibition of delta-aminolevulinic acid dehydratase in liver, kidney and erythrocytes, with an inhibition constant near 3 micromolar. Zinc attenuated that inhibition, suggesting gallium displaces zinc from the enzyme's active sulfhydryl site.

Inhaled gallium arsenide is a different and more serious problem. The National Toxicology Program tested it in Technical Report TR-492, published in 2000, exposing F344/N rats to 0, 0.01, 0.1 or 1.0 mg/m3 and B6C3F1 mice to 0, 0.1, 0.5 or 1.0 mg/m3, for 6 hours a day, 5 days a week, for 105 to 106 weeks. The conclusion was clear evidence of carcinogenic activity in female rats, grounded on increased benign and malignant lung neoplasms; increased benign adrenal medulla pheochromocytomas and increased mononuclear cell leukemia were also considered exposure related. There was no evidence in male rats or in mice of either sex. Shorter 14-week studies at 0.1 to 75 mg/m3 found microcytic anemia, elevated ALT, and testicular atrophy at 37 and 75 mg/m3 in rats and at 10 mg/m3 or greater in mice.

How much of that is gallium rather than arsenic is not resolved. Webb and colleagues instilled the three compounds intratracheally into rats at doses matched to the chemistry rather than to each other: gallium arsenide at 100 mg/kg, gallium trioxide at 65 mg/kg to supply equimolar gallium, and arsenic trioxide at 17 mg/kg as a maximally tolerated nonlethal arsenic dose. All three produced an inflammatory response and pneumonocyte hyperplasia, with severity in descending order gallium arsenide, then arsenic trioxide, then gallium trioxide well behind both. Gallium trioxide was the mildest of the three but not inert: it significantly raised total lung lipid content. IARC's reading is that the gallium moiety is active in its own right.

Signs to reduce or stop

In the clinical setting the stopping rules are explicit: serum creatinine above 2.5 mg/dL, symptomatic hypocalcemia, or any new visual disturbance, since optic neuropathy here has been permanent in at least one reported case. For anyone taking an oral gallium product outside medical supervision, the honest instruction is not a threshold. It is to stop.

General note

Metallic gallium held in the hand is not the hazard. The hazards are soluble salts at pharmacological dose delivered into blood, and inhaled gallium arsenide particulate in industry. Those two scenarios account for essentially all documented gallium harm in humans, and neither describes dietary exposure.

How Gallium Works

Gallium works by being mistaken for iron and then refusing to do iron's job.

The first step is uptake. At plasma concentrations up to about 50 micromolar, essentially all circulating gallium travels as transferrin-gallium; above that the excess circulates as gallate, which the kidney clears rapidly. Transferrin-gallium enters cells by transferrin receptor 1 mediated endocytosis, and because that receptor is upregulated in lymphoma, urothelial cancer and breast cancer, the delivery step self-targets toward the cells that most want iron.

The second step is intracellular sabotage, and it operates on two levels.

• Gallium blocks cellular iron acquisition. It competes with transferrin-iron for the receptor and interferes with endosomal acidification, the step that releases iron from transferrin inside the cell. The net result is cellular iron deprivation.

• Gallium disables ribonucleotide reductase. The R2 subunit needs iron to maintain a tyrosyl free radical. Cytoplasmic extracts from gallium-exposed cells contain apoR2 protein with no EPR-detectable tyrosyl radical signal, and adding an iron salt restores the signal within minutes without changing R2 protein levels. Gallium also directly inhibits CDP and ADP reductase activity in cell-free enzyme assays.

The antibacterial mechanism is the same trick played on a different organism. Gallium substitutes for iron in bacterial uptake systems, binds siderophores, inhibits iron-dependent bacterial enzymes and increases sensitivity to oxidants. Because gallium cannot be reduced, the bacterium acquires it and gains nothing.

The bone effect works differently. Gallium concentrates in bone and inhibits osteoclastic resorption, which is what lowers serum calcium in hypercalcemia of malignancy and what reduced alkaline phosphatase in Paget disease. It is antiresorptive, not anabolic. None of these mechanisms has a low-dose version that produces a health benefit in a person without disease.

Synergistic Supplements

No supplement pairs usefully with gallium, because there is no supplemental use of gallium to enhance. The only meaningful combination data come from the clinical literature and they run in two directions.

Documented pharmacological synergy

• In vitro, gallium has shown synergy with hydroxyurea, fludarabine, interferon-alpha, gemcitabine and paclitaxel, and against P. aeruginosa with certain antibiotics.

• Gallium nitrate has been combined clinically with vinblastine, ifosfamide, fluorouracil, mitoguazone, etoposide and hydroxyurea in bladder cancer and non-Hodgkin lymphoma with acceptable tolerability. One combination is worth noting for the opposite reason: as Chitambar's 2010 review summarizes the literature, gallium nitrate plus fluorouracil produced a 12 percent response rate in bladder cancer against 17 to 63 percent for single-agent gallium across three studies, and the review itself raises the question of antagonism.

Documented antagonism

Iron is the antagonist, and this is not subtle. Because gallium's entire action depends on occupying iron's places, iron availability blunts it. In the thiosemicarbazone work, gallium enhanced the cytotoxicity of 3-aminopyridine-2-carboxaldehyde thiosemicarbazone while iron weakened it, and in the optic neuropathy case report partial recovery followed 12 months of oral ferrous sulfate. Anyone taking gallium and an iron supplement together is taking two products designed to cancel each other, and neither seller will mention it.

Interactions & What NOT to Take

Named drug interactions with real documentation

• Aminoglycosides, named explicitly in the Ganite boxed warning. Gentamicin, tobramycin and amikacin are the ones a hospitalized cancer patient is most likely to be on. The Warrell 1988 protocol excluded patients on concurrent aminoglycoside antibiotics outright.

• Amphotericin B, also named in the boxed warning, for the same reason of additive nephrotoxicity.

• Other agents concentrating renal risk at the same time, including cisplatin, iodinated contrast media and high-dose NSAIDs. These are not named on the 2006 label, but its instruction is categorical about potentially nephrotoxic drugs.

• Diuretics, in a timing-dependent way: the label directs avoiding them until low blood volume is corrected, and notes no adverse interaction with furosemide once hydration was adequate.

• Calcium supplementation, which interacts with the intended effect. The approved use is to lower calcium, and Chitambar's reviews describe oral calcium carbonate as the standard correction for the hypocalcemia that follows in about 38 percent of patients, which makes it also the thing that would undo the therapy if given without reason.

What not to combine with an oral gallium product

Nobody knows, and that is itself the finding. There is no interaction database, no post-marketing surveillance, and no pharmacovigilance of any kind for gallium sold as a supplement, because these products were never registered as anything a regulator tracks.

Quality, Testing & Adulteration

There is no quality infrastructure for gallium as a consumer product, and the market reflects that.

Consider a real listing. Gallium maltolate is sold online as "Gallium Maltolate, ACS 5 grams [Dietary Supplement] Hi-Potency," a powder in a glass ampule, at $4,099.99. The page carries no Supplement Facts panel and no serving size, says dosage should be discussed with a physician, and notes that customers typically buy up to 100 grams. It describes the compound as "a potent blocker of ribonucleotide reductase, an enzyme that promotes tumor growth" and asserts that gallium concentrates in malignant tumors. Purity is given as ">100% (raw virgin matter, ultra-pure)."

Several things are wrong there at once, and they are checkable rather than rhetorical.

• The listing shows no Supplement Facts panel, and a product labeled a dietary supplement must carry one on its label under 21 CFR 101.36. Because gallium has no Reference Daily Intake, that panel would also have to mark it "Daily Value Not Established."

• Statements that a product blocks an enzyme that promotes tumor growth and concentrates in malignant tumors are disease claims, and on these facts FDA would be likely to treat the product as an unapproved new drug rather than a supplement. Structure/function claims under DSHEA require the boldface disclaimer that the statement has not been evaluated by FDA and the product is not intended to diagnose, treat, cure or prevent any disease, and adding that disclaimer does not convert a disease claim into a lawful one.

• Gallium maltolate was not marketed in the United States before October 15, 1994. The Bernstein paper describing its first human administration was published in 2000. Under the new dietary ingredient provision of DSHEA, that would ordinarily trigger a premarket notification requirement.

What verification is available

None. A meaningful certificate would confirm identity by a method distinguishing gallium maltolate from maltol plus a gallium salt, assay gallium against the theoretical 15.7 percent by mass, and test for arsenic, given that gallium's industrial feedstocks and its most important compound both involve arsenic chemistry. NSF/ANSI 173 certification and the USP Dietary Supplement Verification Program test against established specifications, and none exist for gallium. ConsumerLab has no gallium category, so a buyer has no independent verification at any price, including $4,099.99.

Colloidal and trace mineral products

Multi-element "colloidal mineral" liquids drawn from Utah humic shale or Great Salt Lake brine are a quieter version of the same problem. They advertise long lists of trace elements without individually quantifying most of them. If gallium is present it is at levels the manufacturer has not measured. The question for such a product is not how much gallium it holds, but whether the seller can state a quantity for any element named on the front of the bottle.

Special Considerations

Pregnancy and lactation

No adequate human data exist for any gallium compound, and the NTP inhalation program found reproductive and testicular effects in male rats exposed to gallium arsenide. The correct conclusion is not a risk category but an absence: nobody has studied oral gallium in pregnancy, and nobody should become the first case report by accident.

Pediatric use

Gallium radiopharmaceuticals are approved in children, and NETSPOT is labeled for adults and pediatric patients at the same 2 MBq per kg dose. Therapeutic gallium in children exists only in trials, notably the GABRIEL phase 1 of gallium maltolate in relapsed or refractory pediatric high-grade glioma and atypical teratoid rhabdoid tumor.

Renal impairment

The single most important patient-level consideration. Gallium is cleared unchanged by the kidney with no hepatic or renal metabolism, so reduced clearance means accumulation, and what accumulates is renal toxicity. That is why the approved label sets an absolute creatinine threshold rather than a dose adjustment.

Occupational health

Semiconductor fabrication is where gallium exposure is a genuine population health question, through sandblasting gallium arsenide ingots, slicing, grinding and polishing wafers, and cleaning work areas. These are the same operations IARC identified as the predominant sources of gallium arsenide exposure in Monographs Volume 86.

Supply chain, and why gallium is in the news

Gallium is newsworthy in 2026 for reasons unrelated to health, and the numbers are worth knowing so they are not mistaken for a health story. No domestic primary gallium has been recovered in the United States since 1987, and net import reliance is 100 percent. China accounted for 99 percent of worldwide primary low-purity production in 2025. Beijing implemented gallium export controls in August 2023, banned all exports to the United States in December 2024, and lifted that ban for one year in November 2025. Imported gallium metal reached an estimated $580 per kilogram in 2025, about 30 percent above 2024. Integrated circuits accounted for 73 percent of domestic consumption and optoelectronic devices 26 percent. Human nutrition accounted for none of it.

Research Status & Evidence Quality

Strong evidence, multiple randomized controlled trials

Gallium nitrate lowers serum calcium in cancer-related hypercalcemia. Two randomized double-blind trials, 50 and 71 patients, both with active comparators, both statistically significant, supporting the January 17, 1991 approval. The weakness is that both are more than 30 years old, predate bisphosphonate and denosumab standards of care, and used comparators no longer front-line.

Strong evidence, regulatory and routine clinical use

Gallium radiopharmaceuticals as diagnostic agents, across five decades from Ga-67 citrate in 1976 through Gozellix in 2025. That evidence is about imaging accuracy, not about gallium doing anything to the patient.

Moderate evidence, uncontrolled or single-arm trials

Antineoplastic activity in relapsed non-Hodgkin lymphoma, roughly 30 percent response across four single-agent trials, and in advanced bladder cancer, 17 to 63 percent across three. Both of those ranges are review-level summaries from Chitambar rather than pooled analyses. None of the trials was randomized against a modern comparator, and none led to an approval.

Weak evidence, early phase only

Oral gallium maltolate in glioblastoma: one phase 1, 24 patients, dose finding, no control arm. Paget disease: one 49-patient randomized dose-finding trial, never followed up.

Contested or negative

Systemic gallium for Pseudomonas in cystic fibrosis: encouraging phase 1, then a 119-patient randomized placebo-controlled phase 2 that missed its primary endpoint, with day 28 FEV1 responder counts of 22 of 60 against 17 of 56 (p = 0.811).

No evidence at all

Every wellness, energy, immune, longevity, detoxification and general-supplementation claim. There is not one trial.

Research Limitations

Almost all human therapeutic data are from the 1980s and 1990s, run against comparators since superseded. The modern oral compound with the best pharmacokinetic profile, gallium maltolate, has a commercially interested developer, Gallixa LLC, whose founder is an author on both the 2000 pharmacokinetic paper and the 2026 glioblastoma phase 1. That is disclosed and normal for orphan-scale development, but it means the oral literature is concentrated rather than independently replicated.

The oral human dose range studied is narrow: single doses of 100 to 500 mg in 12 healthy volunteers, and daily doses of 500 to 2,500 mg in 24 brain tumor patients. That is the whole oral human safety database, and there is essentially no long-term data for any gallium compound by any route. Nobody knows what daily oral gallium does to a healthy person over years, because the question has never been asked.

Summary & Key Takeaways

Bottom Line

Gallium is a real drug element with a real approval file, and none of that file describes a supplement. NDA 019961 covers a 24-hour intravenous infusion given for five days in a hospital, with a boxed warning, a hydration protocol targeting 2 L of urine per day, serial creatinine monitoring and a hard contraindication above 2.5 mg/dL. That product has not been marketed in the United States for years, and its application holder is a Chapter 7 trustee. The other approved gallium products are diagnostic radiotracers. Oral gallium exists only inside clinical trials. If you have seen gallium offered for sale as something to swallow for health, you have seen a research compound relabeled into a category with no evidence behind it.

Key Safety Points

• Gallium has no biological requirement, no Reference Daily Intake, no EFSA dietary reference value, and no deficiency state. Any Supplement Facts panel listing it must say "Daily Value Not Established."

• The dose-limiting toxicity in humans is renal, driven by intratubular precipitation of gallium with calcium and phosphate, managed with hydration and creatinine monitoring that no consumer product provides.

• Concurrent aminoglycosides and amphotericin B are named in the boxed warning for additive nephrotoxicity.

• Oral gallium maltolate at research doses caused grade 1 or 2 diarrhea, anorexia, nausea and fatigue in all 24 patients in the only modern trial, and drove mean corpuscular volume below normal in 9.

• Gallium arsenide, the industrial form, is an IARC Group 1 human carcinogen, controlled at work through the inorganic arsenic standard. That is an occupational exposure issue, not a dietary one.

Special Note

The most useful thing to understand about gallium is why it works when it works. It is an iron impostor with the right ionic radius and no redox chemistry, so transferrin carries it into iron-hungry cells where it occupies the machinery and does nothing. Against a lymphoma cell or a Pseudomonas colony, that is a weapon. Against a healthy person it is a slow subtraction from iron metabolism with no offsetting return, which is what the falling mean corpuscular volume in the glioblastoma trial was showing. Every element useful as a drug has a dose, a route and a patient. Gallium has all three well documented, and in every case the route runs through a vein or a PET camera, and the patient has a diagnosis.