What are the top three side effects of omeprazole?

Most Common Side Effects of Omeprazole

Omeprazole, a proton pump inhibitor used for acid reflux and ulcers, most often causes headache, abdominal pain, and nausea. These occur in more than 1% of users based on clinical data and FDA labeling.[1][2]

Why These Top Three?

• Headache: Affects up to 7% of patients; linked to the drug's impact on stomach acid regulation, though the exact mechanism is unclear.[1]
  
• Abdominal pain: Reported in 5% of cases; often mild stomach discomfort from altered gastric environment.[2]
  
• Nausea: Seen in 4% of users; typically resolves as the body adjusts.[1]
  
  These rank highest in frequency from large-scale trials and post-marketing reports.[2]
  
  

How Long Do They Last?

Most resolve within days to weeks. Headache and nausea often fade after the first dose; persistent abdominal pain may signal dosage issues or interactions.[1][3]

What If They Don't Go Away?

Consult a doctor if side effects last over two weeks or worsen. They could indicate rare issues like low magnesium or infections from reduced stomach acid.[2]

Rarer but Serious Side Effects

Beyond the top three, watch for diarrhea (possibly C. diff-related), bone fractures with long-term use, or kidney problems. Long-term users (over a year) face higher risks.[1][3]

Comparisons to Other PPIs

Omeprazole's profile matches esomeprazole and pantoprazole, but lansoprazole users report slightly more diarrhea. All share similar common effects.[2]

[1]: FDA Label for Prilosec (omeprazole)
[2]: Drugs.com - Omeprazole Side Effects
[3]: Mayo Clinic - Omeprazole