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Prilosec and Zegerid are both powerful medicines used to treat stomach ailments. Although the medicines are chemically similar, Prilosec and Zegerid are available in different forms and have different side effects.

Active Ingredients

Both Prilosec and Zegerid contain omeprazole, a proton pump inhibitor that stops the stomach from producing acid. However, Zegerid also contains baking soda, which soaks up excess stomach acid and makes it more effective in fighting gastroesophageal reflux disease (GERD) and heartburn.


Prilosec and Zegerid are both used to treat heartburn, GERD and ulcers. According to WebMD, however, Zegerid is used for patients with a higher risk of stomach bleeding.


Over-the-counter Prilosec is only available in pill form, but Zegerid is available in both pill and powder form. The powder makes the medicine easier to swallow, because it can be easily dissolved in a glass of water.

Side Effects

While both medicines can cause constipation, headache, diarrhea, abdominal pain, nausea and dizziness, Prilosec can also cause back pain and a vitamin B12 deficiency, if it is taken for more than three years.

Drug Interactions and Precautions

Neither Prilosec nor Zegerid can be taken with atazanavir or nelfinavir. In addition, if you have high blood pressure or are on a low-salt diet, your doctor may not recommend Zegerid for your condition, as Zegerid contains sodium, unlike Prilosec.