If you experience symptoms of acid reflux or heartburn, your doctor may prescribe Prilosec (omeprazole) or Protonix (pantoprazole) to decrease the amount of acid produced in your stomach 12. Both drugs belong to a group of medications called proton pump inhibitors. Prilosec is also available without a prescription under the name Prilosec OTC, which may be less expensive than prescription proton pump inhibitors, depending on your insurance coverage 15. Because Prilosec and Protonix work in the same way, they are typically not taken together 12.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

FDA-Approved Uses

Although Prilosec, Prilosec OTC and Protonix are in the same class of medications, they are approved by the Food and Drug Administration (FDA) for somewhat different conditions 125. This is often what guides doctors to choose 1 medication over another. Of the 3 medications, only Prilosec is approved to treat ulcers in the stomach or small intestine, heartburn and other symptoms related to gastroesophageal reflux disease, as well as ulcers caused by H. pylori infection 1. Prilosec OTC is approved only for the treatment of frequent heartburn 15. Both Prilosec and Protonix are approved for 2 other reasons: inflammation in the esophagus -- called esophagitis -- and certain conditions that cause the stomach to make too much acid 12.

Drug Interactions

Prevacid Vs. Protonix

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Both Prilosec and Protonix may interact with other medications 12. Prilosec changes the way the body processes certain antidepressants -- including citalopram (Celexa) and escitalopram (Lexapro) -- and certain medications that affect blood clotting -- including warfarin (Coumadin, Jantoven) and clopidogrel (Plavix) 1. Interactions also exist between Prilosec and other drugs or substances, such as diazepam (Valium), phenytoin (Dilantin), ginkgo biloba and St. John's wort 1. Protonix appears to be less likely than Prilosec to interact with most other medications, according to a review published in April 2014 in the journal "Drug Safety." Because of the possibility of interactions, inform your doctor or pharmacist about all medications or supplements that you are taking before beginning Prilosec, Prilosec OTC or Protonix 125.

Side Effects

The side effects of Prilosec and Protonix are similar, with headache being the most common side effect of both medications 12. Headaches may be less common with Prilosec 1. According to the FDA-approved prescribing information, headaches occurred in 12.2 percent of participants in clinical trials treated with Protonix and 6.9 percent of those treated with Prilosec 12. Other potential side effects of both medications include abdominal pain, nausea, diarrhea, vomiting and gas. A small percentage of participants in clinical trials for Protonix noted dizziness and joint pain 2. Report any persistent or bothersome side effects to your doctor.

Serious Reactions

Possible Side Effects of Antacids and Acid Reducers

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Taking Prilosec, Protonix or other proton pump inhibitors increases your risk of developing osteoporosis-related fractures, low magnesium levels in the blood and Clostridium difficile infection 12. Notify your doctor immediately if you experience symptoms of C. difficile -- including persistent diarrhea, fever and abdominal pain -- or symptoms of low magnesium levels -- including muscle cramps, seizures and heart palpitations. Although rare, a severe allergic reaction may occur with any proton pump inhibitor. If you develop hives, swelling, lightheadedness or difficulty breathing while taking Prilosec or Protonix, seek emergency medical care 12.

Reviewed by: Mary D. Daley, MD