Famotidine

Famotidine is a member of the H-2 blocker (histamine blocker) family of drugs that prevents the release of acid into the stomach. Famotidine is used to treat stomach and duodenal ulcers, reflux of stomach acid into the esophagus, and Zollinger-Ellison syndrome. Famotidine is available as a prescription drug and as a nonprescription product for relief of heartburn, acid indigestion, and sour stomach.

Safetychecker Summary for Famotidine
(for details about the summarized interactions, read the full article)

May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.	Iron* Vitamin B12
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	Tobacco
Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.	Copper Folic acid Magnesium
Side effect reduction/prevention	None known
Supportive interaction	None known
Reduced drug absorption/bioavailability	None known

Interactions with Dietary Supplements

Iron
Stomach acid may increase absorption of iron from food. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption.¹ The iron found in supplements is available to the body without the need for stomach acid. People with ulcers may be iron deficient due to blood loss. If iron deficiency is present, iron supplementation may be beneficial. Iron levels in the blood can be checked with lab tests.

Magnesium-containing antacids
In healthy people, a magnesium hydroxide/aluminum hydroxide antacid, taken with famotidine, decreased famotidine absorption by 20–25%.² People can avoid this interaction by taking famotidine two hours before or after any aluminum/magnesium-containing antacids. Some magnesium supplements such as magnesium hydroxide are also antacids.

Vitamin B12
Stomach acid is needed for the vitamin B12 in food to be absorbed. H-2 blocker drugs reduce stomach acid and may therefore inhibit absorption of the vitamin B12 naturally present in food. However, the vitamin B12 found in supplements does not depend on stomach acid for absorption.³ Lab tests can determine vitamin B12 levels in people.

Other vitamins and minerals
Some evidence indicates that other vitamins and minerals, such as folic acid ⁴ and copper,⁵ require the presence of stomach acid for optimal absorption. Long-term use of H-2 blockers may therefore promote a deficiency of these nutrients. Individuals requiring long-term use of H-2 blockers may therefore benefit from a multiple vitamin/mineral supplement.

Interactions with Foods and Other Compounds

Food
Famotidine may be taken with or without food.⁶ To prevent heartburn after meals, famotidine is best taken one hour before meals.⁷

Tobacco
In a study of 18 healthy people, cigarette smoking was found to decrease the acid blocking effects of famotidine.⁸ A double-blind, randomized study of 594 patients with duodenal ulcers found that smoking inhibited the ulcer-healing effect of famotidine.⁹

References:

1. 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.

2. Bachmann KA, Sullivan TJ, Jauregui L, et al. Drug interactions of H2-receptor antagonists. Scand J Gastroenterol Suppl 1994;206:14–9.

3. 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.

4. Russell RM, Krasinski SD, Samloff IM. Correction of impaired folic acid (Pte Glu) absorption by orally administered HCl in subjects with gastric atrophy. Am J Clin Nutr 1984;39:656.

5. Tompsett SL. Factors influencing the absorption of iron and copper from the alimentary tract. Biochem J 1940;34:961–9.

6. Lin JH, Chremos AN, Kanovsky SM, et al. Effects of antacids and food on absorption of famotidine. Br J Clin Pharmacol 1987;24:551–3.

7. Threlkeld DS, ed. Gastrointestinal Drugs, Histamine H2 Antagonists, Famotidine. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Sep 1995, 305f–5g.

8. Schurer-Maly CC, Varga L, Koelz HR, Halter F. Smoking and pH response to H2-receptor antagonists. Scand J Gastroenterol 1989;24:1172–8.

9. Reynolds JC, Schoen RE, Maislin G, Zangari GG. Risk factors for delayed healing of duodenal ulcers treated with famotidine and ranitidine. Am J Gastroenterol 1994;89:571–80.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2003.