What is Prilosec (Omeprazole)? Uses and Adverse Effects

Prilosec Is a Proton-Pump Inhibitor (PPI)

GERD. Credit: Photo © A.D.A.M.

What Prilosec (Omeprazole) Is Used For

Prilosec (omeprazole) is used to help treat gastric ulcers, duodenal ulcers, GERD and erosive esophagitis. Prilosec is also used to treat H. pylori (a common ulcer-causing bacteria). Over-the-counter Prilosec is also available for the treatment of frequent heartburn that occurs more than 2 times per week.

How Prilosec (Omeprazole) Works

Prilosec is a proton pump inhibitor, which helps block gastric cells that produce acid in the stomach.

In GERD, ulcers and esophagitis, too much acid can be harmful to the lining of the esophagus, stomach or intestines. By reducing the amount of acid secreted into the stomach, Prilosec and other proton pump inhibitors can help minimize damage that occurs when acid levels are high.

How Prilosec (Omeprazole) Is Taken

Prilosec should be taken before meals. Capsules should be swallowed whole and not chewed. If you have swallowing difficulties, the contents of the Prilosec capsule may be mixed into applesauce or similar substances. Make sure that the pellets found within the capsule are not crushed or chewed when swallowing.

Usual doses include 20 mg once a day (sometimes may be given twice a day), 40 mg once a day, and 60 mg once a day. It is important that you follow your physician’s orders on dosing, as more Prilosec does not equal better results.

Adverse Effects of Prilosec

The most common adverse effects of Prilosec are (listed in the order of prevalence):

Other adverse effects (listed in order of prevalence):

  • acid regurgitation
  • upper respiratory infection
  • constipation
  • dizziness
  • rash
  • weakness
  • back pain
  • cough

You should see a doctor immediately if you experience the following symptoms, which may be related to an allergic reaction.

Symptoms in bold require emergency medical treatment:

  • rash, hives, or other skin reactions
  • difficulty breathing
  • wheezing
  • difficulty swallowing

Prilosec (Omeprazole) and Interference With Other Medications

You should consult your physician if you are taking any of the following medications as they can interact with Prilosec. As this list is incomplete, you should always contact your physician prior to starting a new medication. Your physician or pharmacist can run a check for interactions between your prescribed medications.

  • warfarin
  • ketoconazole
  • ampicillin
  • Valium
  • phenytoin
  • Antabuse
  • cyclosporine
  • Prograf
  • Plavix
  • Atazanavir

Prilosec Linked to Bone Fractures

Prilosec and other proton-pump inhibitors (PPIs) have been linked to increased risk of bone fractures, including fractures of the wrist, spine and hip. The highest number of such fractures occur in people who take these drugs at high doses for a year or longer. Please note that over-the-counter PPIs are meant to only be taken for a few weeks, and ideally under the supervision of a physician.

If you need these medications long term, you should discuss such continuing treatment with your physician.

Before Taking Prilosec

Before beginning Prilosec, you should consult your physician. Prilosec is not for acute symptoms (symptoms occurring right now) of heartburn. Rather, it is used for long-term resolution of symptoms.

If you have black stools or bright red blood in stools, you should seek medical attention rather than using Prilosec. If you are pregnant, planning to become pregnant or nursing a baby, you should consult your physician before taking Prilosec. Always have a doctor or pharmacist review you current medication list before starting a new medication.


AstraZeneca. (2008). Prilosec Prescribing Information. Accessed: June 12, 2010 from http://www.accessdata.fda.gov/drugsatfda_docs/label/2008/022056lbl.pdf

Medline Plus. (2010). Omeprazole. Accessed: June 12, 2010 from http://www.nlm.nih.gov/medlineplus/druginfo/meds/a693050.html

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