Drug Information

Omeprazole is a member of the proton pump inhibitor family of drugs, which blocks production of stomach acid. Omeprazole is used to treat diseases in which stomach acid causes damage, including gastric and duodenal ulcers, gastroesophageal reflux disease, erosive esophagitis, and Zollinger-Ellison syndrome.

Common brand names:

Prilosec, Prilosec OTC

Summary of Interactions with Vitamins, Herbs, & Foods

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Calcium

    In a study of elderly women, administration of omeprazole decreased the absorption of calcium, presumably because the drug decreased the stomach's production of hydrochloric acid, which is necessary for calcium absorption. The form of calcium used in the study to test calcium absorption was calcium carbonate. Drugs that reduce stomach acid secretion may not inhibit other forms of calcium, such as calcium citrate.

  • Folic Acid

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

  • Vitamin C

    Treatment of healthy volunteers with omeprazole for four weeks resulted in a 12.3% decrease in blood levels of vitamin C.

  • Vitamin B12

    Omeprazole interferes with the absorption of vitamin B12 from food (though not from supplements) in some but not all studies. A true deficiency state, resulting in vitamin B12-deficiency anemia, has only been reported in one case. The fall in vitamin B12 status may result from the decrease in stomach acid required for vitamin B12 absorption from food caused by the drug. This problem may possibly be averted by drinking acidic juices when eating foods containing vitamin B12.

    However, all people taking omeprazole need to either supplement with vitamin B12 or have their vitamin B12 status checked on a yearly basis. Even relatively small amounts of vitamin B12 such as 10-50 mcg per day, are likely to protect against drug induced vitamin depletion.

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

Reduce Side Effects

  • Cranberry

    People taking omeprazole may increase absorption of dietary vitamin B12 by drinking cranberry (Vaccinium marocarpon) juice or other acidic liquids with vitamin B12-containing foods.

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

Support Medicine

  • none

Reduces Effectiveness

  • St. John's Wort

    In a study of healthy human volunteers, supplementing with St. John's wort greatly decreased omeprazole blood levels by accelerating the metabolism of the drug. Use of St. John's wort may, therefore, interfere with the actions of omeprazole.

Potential Negative Interaction

  • none

Explanation Required 

  • Magnesium
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole). Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%). People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.
    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
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.