Cimetidine & Nutrient Depletion
Also searched as Tagamet HB, Tagamet, Cimetidine Injection. What the clinical evidence reports, what it may mean, and what to discuss with your pharmacist.
Cimetidine has been associated with depletion of CALCIUM, FOLIC ACID, IRON and VITAMIN D and 3 more. This does not mean a deficiency will occur — it means these are worth knowing about and, if you take Cimetidine long-term, worth raising with your pharmacist or healthcare provider.
Take more than one medication? Open the checker with Cimetidine pre-loaded and add the rest to see overlapping nutrient signals.
Reported nutrient depletions with Cimetidine
Each record below is shown as published in our licensed clinical database, with its evidence rating and citations. Expand a section for food sources and talking points.
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CALCIUM
Insignificant DepletionH2-BLOCKERS
Calcium must be solubilized in order to be absorbed. The solubility of calcium is dependent on an acidic pH. Therefore, it has been assumed that decreased gastric acidity decreases absorption of calcium supplements. Some evidence also shows that patients with low gastric acid have lower calcium absorption in a fasting state compared to people with normal gastric acid secretion. Calcium citrate is significantly better absorbed than calcium carbonate in these patients in a fasting state. However, when taken with a meal, decreased gastric acidity due to drugs such as H2 blockers or due to achlorhydria, does not seem to significantly impair absorption of calcium carbonate or calcium citrate. For information on foods that are rich in calcium, see our chart.
Calcium keeps your bones strong and helps your muscles and heart work properly. Cimetidine reduces stomach acid, and since calcium needs an acidic environment to dissolve and get absorbed, there has been some concern it could modestly reduce how much calcium your body takes in. That said, this effect appears to be minimal when calcium is consumed with food, which is how most people get it, so for the vast majority of patients taking cimetidine this is not considered a real concern. No supplement is needed for most people, but if you have questions about your calcium intake, a quick chat with your pharmacist is always a good idea.
What Calcium does & food sources
Calcium builds and maintains bone and is essential for muscle contraction and nerve signaling.
Common food sources:
- Dairy products (milk, yogurt, cheese)
- Fortified plant milks and juices
- Canned fish with bones (sardines, salmon)
- Leafy greens like kale
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
Ask your provider whether bone health monitoring (and vitamin D testing) makes sense with long-term use of an associated medication — a blood calcium level alone does not capture bone calcium status.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
Calcium can interfere with the absorption of several medications (some antibiotics, thyroid medication, iron) — separate the doses and confirm timing with your pharmacist. Total intake from food plus supplements matters more than supplements alone.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: Very high calcium intake has its own risks (kidney stones in susceptible people) — more is not better.
Learn more about this nutrient: Calcium — uses, safety & interactions
FOLIC ACID
Insignificant DepletionH2 BLOCKERS
Folic acid absorption from the small intestine is optimal at a pH of 5.5-6. The increased pH associated with use of H2 blockers may therefore reduce folic acid absorption, but this is probably only significant if dietary folate intake is very low. Advise patients to maintain the recommended daily dietary intake of folic acid. For information on foods that are rich in folate, see our chart.
Folic acid is a B vitamin your body needs to build new cells and keep your blood healthy. Cimetidine works by reducing stomach acid, and because folate absorbs best in a slightly acidic environment in the small intestine, there is a theoretical possibility that less of it gets taken in. That said, researchers consider this effect too small to matter for most people eating a reasonably balanced diet, so a supplement is not considered necessary for the average cimetidine user. If you are worried about your folate intake, a quick chat with your pharmacist or doctor can put your mind at ease.
What Folic acid (folate) does & food sources
Folate is needed for cell division, red blood cell formation, and healthy fetal development.
Common food sources:
- Leafy green vegetables
- Beans, lentils, and peas
- Fortified grains and cereals
- Citrus fruits
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
Ask your provider whether folate monitoring or supplementation is appropriate for you — this matters most before and during pregnancy, and with long-term use of certain seizure or arthritis medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
Folate needs are individual. With some medications (for example, methotrexate), folic acid is often prescribed deliberately on a specific schedule — follow your prescriber's instructions rather than adding your own.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: High-dose folic acid can mask vitamin B12 deficiency, so the two are often evaluated together.
Learn more about this nutrient: Folic Acid — uses, safety & interactions
References (2)
- Russell RM, Golner BB, Krasinski SD, et al. Effect of antacid and H2 receptor antagonists on the intestinal absorption of folic acid. J Lab Clin Med 1988;112:458-63.
- Termanini B, Gibril F, Sutliff VE, et al. Effect of long-term gastric acid suppressive therapy on serum vitamin B12 levels in patients with Zollinger-Ellison syndrome. Am J Med 1998;104:422-30. PubMed
IRON
Insignificant DepletionH2-BLOCKERS
Gastric acid is important for the absorption of iron, particularly dietary non-heme iron. Dose-dependent reductions in dietary iron absorption have been noted with cimetidine, ranging from 28% to 65% with single doses of 300-900 mg. However, long-term treatment, up to 18 years, with H2-blockers isn't associated with iron depletion or anemia in people with normal iron stores. Advise people to maintain adequate dietary iron intake. Supplements aren't necessary unless people have other factors contributing to iron deficiency. For information on foods that are rich in iron, see our chart.
Iron is something your body needs to make healthy red blood cells and carry oxygen through your bloodstream. Cimetidine reduces stomach acid, and your gut actually relies on that acid to pull iron out of food and into your system, so the medication can dial back how much iron you absorb from a meal. That said, studies following people on H2-blockers for many years have not found meaningful iron depletion in healthy individuals, which is why this is rated insignificant for most people. Eating iron-rich foods regularly is a reasonable habit, and if you have other reasons to worry about your iron levels, it is worth a quick conversation with your pharmacist or doctor.
What Iron does & food sources
Iron is the core of hemoglobin, which carries oxygen in red blood cells.
Common food sources:
- Red meat and poultry
- Beans and lentils
- Fortified cereals
- Spinach (plant iron absorbs better with vitamin C)
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
Iron status is easy to assess (ferritin, iron studies, blood counts). Ask your provider before supplementing — unexplained low iron always deserves a medical evaluation for the cause, not just replacement.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
Iron supplements commonly cause constipation or stomach upset and interfere with the absorption of several medications (thyroid medication, some antibiotics). Do not take iron "just in case" — excess iron is harmful.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: Never self-treat suspected anemia; the underlying cause matters as much as the iron level.
Learn more about this nutrient: Iron — uses, safety & interactions
References (4)
- Aymard JP, Aymard B, Netter P, et al. Haematological adverse effects of histamine H2-receptor antagonists. Med Toxicol Adverse Drug Exp 1988;3:430-48. PubMed
- Skikne BS, Lynch SR, Cook JD. Role of gastric acid in food iron absorption. Gastroenterology 1981;81:1068-71. DOI
- Termanini B, Gibril F, Sutliff VE, et al. Effect of long-term gastric acid suppressive therapy on serum vitamin B12 levels in patients with Zollinger-Ellison syndrome. Am J Med 1998;104:422-30. PubMed
- Stewart CA, Termanini B, Sutliff VE, et al. Iron absorption in patients with Zollinger-Ellison Syndrome treated with long-term gastric acid antisecretory therapy. Aliment Pharmacol Ther 1988;12:83-98.. PubMed
VITAMIN D
Insignificant DepletionCIMETIDINE (Tagamet)
Cimetidine inhibits an enzyme involved in conversion of vitamin D to its active form in the liver. However, it does not affect formation of active vitamin D metabolites in the kidneys. Clinically significant vitamin D depletion is not likely, except in people with other risk factors such as liver or kidney disease.
Vitamin D helps your body absorb calcium and keep your bones strong, and it also plays a role in immune health. Cimetidine appears to slow down a liver enzyme that converts vitamin D into a form your body can use, though your kidneys can still do their part of that process just fine. Because of that backup pathway, meaningful vitamin D depletion is considered unlikely for most people taking cimetidine. Unless you have liver or kidney disease or other risk factors, there is no particular reason to worry, though it is always fine to bring it up with your pharmacist.
What Vitamin D does & food sources
Vitamin D helps the body absorb calcium and supports bone, muscle, and immune health.
Common food sources:
- Fatty fish (salmon, mackerel)
- Fortified milk and cereals
- Egg yolks
- Sunlight exposure (the main natural source)
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
A 25-hydroxyvitamin D blood test is the standard way to assess status — ask whether it is appropriate if you take an associated medication long-term, have limited sun exposure, or have bone concerns.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
Vitamin D dosing varies a lot between people; some medications change how vitamin D is processed. Your provider can target a dose to your level instead of guessing.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: Vitamin D is fat-soluble and can accumulate — very high doses over time can cause harm, so follow a clinician-guided plan.
Learn more about this nutrient: Vitamin D — uses, safety & interactions
References (3)
- Odes HS, Fraser GM, Krugliak P, et al. Effect of cimetidine on hepatic vitamin D metabolism in humans. Digestion 1990;46:61-4. PubMed
- Bengoa JM, Bolt MJ, Rosenberg IH. Hepatic vitamin D 25-hydroxylase inhibition by cimetidine and isoniazid. J Lab Clin Med 1984;104;546-52.
- Cimetidine inhibits the hepatic hydroxylation of vitamin D. Nutr Rev 1985;43:184-5.
ZINC
Insignificant DepletionH2-BLOCKERS
Limited data suggest inhibition of gastric acid secretion by H2-blockers might reduce absorption of zinc from supplements, but clinically significant zinc depletion hasn't been reported.
Zinc is a mineral your immune system, wound healing, and sense of taste all depend on. Cimetidine works by reducing stomach acid, and there is some thought that lower acid levels could slightly slow how well zinc from supplements gets absorbed in the gut. That said, real-world zinc deficiency from cimetidine has not been reported, so this is considered an insignificant concern for most people. No action is needed, but if you take cimetidine long-term and have questions about your zinc intake, your pharmacist or doctor is a great person to ask.
What Zinc does & food sources
Zinc supports immune function, wound healing, taste and smell, and many enzyme systems.
Common food sources:
- Meat and shellfish (especially oysters)
- Beans and lentils
- Nuts and seeds
- Whole grains
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
Ask about zinc status if you take an associated medication long-term and notice slow wound healing, frequent infections, or taste changes — a clinician can decide whether testing or an empiric plan makes sense.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
Zinc competes with copper for absorption — long-term, higher-dose zinc without medical guidance can cause copper deficiency. Zinc also binds some antibiotics in the gut, so dose timing matters.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: Keep zinc doses moderate and time them away from interacting medications — ask your pharmacist.
Learn more about this nutrient: Zinc — uses, safety & interactions
References (1)
- Sturniolo GC, Montino MC, Rossetto L, et al. Inhibition of gastric acid secretion reduces zinc absorption in man. J Am Coll Nutr 1991;10:372. PubMed
VITAMIN B12
Moderate DepletionH2-BLOCKERS
Reduced secretion of gastric acid and pepsin produced by H2-blockers can reduce absorption of protein-bound (dietary), but not supplemental, vitamin B12. This is because gastric acid is needed to release vitamin B12 from protein for absorption. Clinically significant vitamin B12 deficiency and megaloblastic anemia are unlikely, unless H2-blocker therapy is prolonged (2 years or more) or dietary vitamin B12 is low. The odds of developing vitamin B12 deficiency are 25% higher in individuals taking H2-blockers for 2 years or more compared to non-users. Vitamin B12 deficiency is also more likely with prolonged, high-dose H2-blocker therapy than with prolonged, low-dose therapy and in people rendered achlorhydric, which occurs more frequently with proton pump inhibitors than H2-blockers. Vitamin B12 deficiency is expected to diminish upon discontinuation of H2-blocker therapy. For information on foods that are rich in vitamin B12, see our chart.
Vitamin B12 is something your nerves and red blood cells genuinely depend on, so it is worth understanding how cimetidine fits in. Your stomach normally makes acid that frees B12 from the food you eat so it can be absorbed, and cimetidine works by dialing that acid production down. That means dietary B12 from meat, dairy, and eggs may not get absorbed as well, though B12 from supplements slips through just fine since it does not need the acid step. For most people on short-term or low doses, this is unlikely to cause a real problem, but if you have been taking cimetidine for two years or longer, it is a reasonable thing to bring up with your pharmacist or doctor.
What Vitamin B12 does & food sources
Vitamin B12 supports red blood cell formation, nerve function, and DNA synthesis.
Common food sources:
- Meat, poultry, and fish
- Eggs and dairy products
- Fortified cereals and nutritional yeast
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
What to discuss with your clinician
If you take an associated medication long-term, ask your healthcare provider whether checking a vitamin B12 level (sometimes with methylmalonic acid) is appropriate — especially if you notice fatigue, numbness, tingling, or memory changes.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Supplement considerations
B12 status is easy to check and low levels are usually straightforward to address, so testing before supplementing is often the sensible order. High-dose folic acid can mask a B12 deficiency, which is one reason B12 and folate questions are best sorted out together with your provider.
Do not start or stop medications or supplements without professional guidance — supplements can interact with prescription medications.
HelloPharmacist pharmacist-reviewed education — separate from the licensed record above.
Caution: B12 deficiency can look like other conditions — do not self-diagnose from symptoms alone.
Learn more about this nutrient: Vitamin B12 — uses, safety & interactions
References (8)
- Aymard JP, Aymard B, Netter P, et al. Haematological adverse effects of histamine H2-receptor antagonists. Med Toxicol Adverse Drug Exp 1988;3:430-48. PubMed
- Belaiche J, Zittoun J, Marquet J, et al. Effect of ranitidine on secretion of gastric intrinsic factor and absorption of vitamin B12. Gastroenterol Clin Biol 1983;7:381-4.
- Salom IL, Silvis SE, Doscherholmen A. Effect of cimetidine on the absorption of vitamin B12. Scand J Gastroenterol 1982;17:129-31.
- Ruscin JM, Page RL, Valuck RJ. Vitamin B12 deficiency associated with histamine-2-receptor antagonists and a proton-pump inhibitor. Ann Pharmacother 2002;36:812-6.
- Force RW, Nahata MC. Effect of histamine H2 receptor antagonists on vitamin B12 absorption. Ann Pharmacother 1992;26:1283-6.
- Force RW, Meeker AD, Cady PS, et al. Increased vitamin B12 requirement associated with chronic acid suppression therapy. Ann Pharmacother 2003;37:490-3.
- Lam JR, Schneider JL, Zhao W, et al. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA 2013;310:2435-42.
- Termanini B, Gibril F, Sutliff VE, et al. Effect of long-term gastric acid suppressive therapy on serum vitamin B12 levels in patients with Zollinger-Ellison syndrome. Am J Med 1998;104:422-30. PubMed
CHROMIUM
Insufficient EvidenceH2-BLOCKERS
H2-blockers increase the gastric pH, which might decrease chromium absorption due to formation of less soluble chromium salts. However, the clinical significance of this is not clear.
Chromium is a trace mineral your body uses to help insulin work properly and keep blood sugar in a normal range. Cimetidine reduces stomach acid, and there is some thought that less acid in the stomach could make chromium harder to absorb, since chromium seems to dissolve better in a more acidic environment. That said, the evidence here is quite thin, and right now it is not clear whether this matters at all in real patients. If you have been on cimetidine for a long time and are curious, it is worth mentioning to your pharmacist or doctor.
Learn more about this nutrient: Chromium — uses, safety & interactions
References (1)
- Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
This tool is educational and is not a substitute for professional medical advice. An association is not a diagnosis and does not mean a deficiency will occur. Always talk to your pharmacist or healthcare provider before starting, stopping, or changing any medication or supplement.
Disclaimer: This checker finds which nutrients might be depleted by prescription or over-the-counter medications. Each nutrient depletion issue is rated based on clinical significance. Use your own professional judgment prior to making clinical decisions.© 2026 Therapeutic Research Center Licensed records refresh weekly · last updated July 3, 2026.
More about Cimetidine
What drug-induced nutrient depletion means
Some medications can, over time, lower the levels of certain vitamins, minerals, or other nutrients — through reduced absorption, increased loss, or changes in how the body uses them.
Association is not deficiency
An entry here means a depletion has been reported or studied — not that it happens to everyone, or that you are deficient. Dose, duration, diet, and your own health all matter.
Evidence varies by pair
Some drug–nutrient links (like metformin and vitamin B12) are well studied; others rest on limited or preliminary research. Each entry shows the evidence rating from our licensed clinical database.
When to ask about labs
If you take an associated medication long-term, ask your healthcare provider whether monitoring is appropriate for you. Not everyone needs testing — your provider can weigh your dose, duration, and symptoms.
Don't self-supplement blindly
Supplements are not risk-free: some can interact with medications, and some (like potassium or magnesium) can be risky with kidney disease. Talk to your pharmacist before adding anything.
Never stop a medication over this
These medications are prescribed for good reasons, and the benefit usually far outweighs a manageable nutrient consideration. Any change belongs in a conversation with your prescriber.
Food first, usually
For many nutrients, a varied diet covers the gap. Each entry lists common food sources; a supplement is a decision to make with your pharmacist or provider, not a default.
Cimetidine & nutrients: FAQs
Does Cimetidine deplete CALCIUM?
Should I take a supplement because I take Cimetidine?
Should I stop taking Cimetidine?
Where does this information come from?
Questions about Cimetidine and your nutrition?
Ask a licensed pharmacist — free, no appointment needed.
Sources & How We Checked
Nutrient depletion records for Cimetidine are evidence-graded and sourced from the Natural Medicines database, and are displayed as published with their citations.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference for drug-induced nutrient depletions, supplements, and interactions — the basis for this page.
- MedlinePlus, U.S. National Library of Medicine — NIH consumer drug information, used for medication overviews across the site.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.