Drug Information

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

Common brand names:

Acid Reducer 200, Tagamet, Tagamet HB

Summary of Interactions with Vitamins, Herbs, & Foods

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Copper

    There is some evidence that other vitamins and minerals, such as folic acid and copper, 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.

  • Folic Acid

    Folic acid is needed by the body to utilize vitamin B12. Antacids, including nizatidine, inhibit folic acid absorption. People taking antacids are advised to supplement with folic acid.

    There is some evidence that other vitamins and minerals, such as folic acid and copper, 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.

  • Iron

    Stomach acid may facilitate iron absorption. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption. People with ulcers may also be iron deficient due to blood loss and benefit from iron supplementation. Iron levels in the blood can be checked with lab tests.

  • Vitamin B12

    Hydrochloric acid is needed to release vitamin B12 from food so it can be absorbed by the body. Cimetidine, which reduces stomach acid, may decrease the amount of vitamin B12 available for the body to absorb. The vitamin B12 found in supplements is available to the body without the need for stomach acid. Lab tests can determine vitamin B12 levels in people.

  • Vitamin D

    Cimetidine may reduce vitamin D activation by the liver. Lab tests can measure activated vitamin D levels in the blood. Forms of vitamin D that do not require liver activation are available, but only by prescription.

  • Beta-Carotene

    Omeprazole , a drug closely related to lansoprazole, taken for seven days led to a near-total loss of stomach acid in healthy people and interfered with the absorption of a single administration of 120 mg of beta-carotene. It is unknown whether repeated administration of beta-carotene would overcome this problem or if absorption of carotenoids from food would be impaired. Persons taking omeprazole and related acid-blocking drugs for long periods may want to have carotenoid blood levels checked, eat plenty of fruits and vegetables, and consider supplementing with carotenoids.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Reduce Side Effects

  • none

Support Medicine

  • none

Reduces Effectiveness

  • Magnesium

    In healthy volunteers, a magnesium hydroxide/aluminum hydroxide antacid, taken with cimetidine, decreased cimetidine absorption by 20 to 25%. People can avoid this interaction by taking cimetidine two hours before or after any aluminum/magnesium-containing antacids, including magnesium hydroxide found in some vitamin/mineral supplements. However, the available studies do not clearly indicate if magnesium hydroxide was the problem and may not need to be avoided.

Potential Negative Interaction

  • Foods with Caffeine

    Caffeine is found in coffee, tea, soft drinks, chocolate, guaraná (Paullinia cupana), nonprescription over-the-counter drug products, and supplement products containing caffeine or guaraná. Cimetidine may decrease the clearance of caffeine from the body, causing increased caffeine blood levels and unwanted actions. People taking cimetidine may choose to limit their caffeine intake to avoid problems. They should read food, beverage, drug, and supplement labels carefully for caffeine content.

Explanation Required 

  • none

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.