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What is omeprazole?

Omeprazole (also called Prilosec®) blocks the release of stomach acid. It is used to treat stomach ulcers and other conditions that cause the stomach to produce too much acid. Omeprazole can relieve the pain and discomfort caused by ulcers and heartburn associated with gastroesophageal reflux disease (also called GERD or acid reflux). When combined with antibiotics, omeprazole has also been used to treat a stomach infection caused by a bacterium called Helicobacter pylori. Omeprazole is available in delayed-release form as a 10-mg peach-and-purple capsule and as a 20-mg purple capsule. Both are taken by mouth.

Possible side effects of omeprazole

  • Nausea and vomiting
  • Headache
  • Diarrhea or constipation
  • Rash
  • Feeling dizzy
  • Cold symptoms
  • Cough
  • Pain in abdomen area

These are the most common side effects, but there may be others. Please report all side effects to the doctor or nurse.

In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

Special instructions for omeprazole

  • Do not crush, cut, or chew omeprazole. Swallow the capsule whole.
  • Take omeprazole 30 minutes before meals.
  • Omeprazole may affect the way other medicines work. These medicines include warfarin, phenytoin, diazepam, ketoconazole, itraconazole, ampicillin, and iron. Always tell your doctor if you are taking any of these medicines or if you start taking any new medicine while you are taking omeprazole.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).