Based on NIH | Can omeprazole cause headaches, how common is this side effect, and what should I do if I develop one while taking it?

Omeprazole can cause headaches in some people, and it is considered a common side effect. ^[1] In clinical trials, about 7% of adults taking omeprazole reported headache, which means roughly 7 out of 100 people may experience it. ^[1] Similar rates have been reported across multiple official labels and studies, consistently listing headache among the most frequent side effects. ^[2] Headaches linked to omeprazole are usually mild to moderate and often improve as your body adjusts or after stopping the drug. ^[3]

How common is the headache side effect?

• The most consistently reported estimate is about 7% in controlled studies. ^[1]
• Headache appears alongside other common side effects like abdominal pain (about 5%), nausea (about 4%), diarrhea (about 4%), vomiting (about 3%), and gas (about 3%). ^[1]
• Multiple official product summaries repeat this 7% figure for headache, reinforcing that it is a recognized common effect. ^[2]
• Large reviews comparing omeprazole with placebo and H2 blockers found a similar overall side‑effect profile, with headache among the most frequent but typically mild events. ^{[4] [3]}

Quick reference table

Side effect (adults)	Approximate incidence in trials
Headache	~7% [1] [2]
Abdominal pain	~5% [1]
Nausea	~4% [1]
Diarrhea	~4% [1]
Vomiting	~3% [1]
Gas (flatulence)	~3% [1]

What to do if you develop a headache

• Consider simple measures first: rest, hydration, and, if appropriate for you, a short course of acetaminophen (paracetamol). ^[3]
• Many headaches are temporary and may settle as treatment continues, so observing for a few days can be reasonable if symptoms are mild. ^[3]
• If the headache is persistent, worsening, or interferes with daily life, it would be reasonable to discuss dose timing (e.g., taking omeprazole earlier in the day), dose adjustment, or switching to an alternative acid reducer with your clinician. ^[4]
• Seek prompt medical advice if your headache is severe, sudden “thunderclap,” associated with fever, neck stiffness, confusion, weakness, vision changes, or follows a head injury, as these features suggest other causes needing urgent evaluation. ^[4]

When to consider stopping or switching

• If headaches are clearly linked to your doses and recur despite simple measures, your clinician may suggest trying a different proton pump inhibitor or an H2 blocker, since overall tolerability is similar across these classes and some individuals do better with one than another. ^[4]
• Decisions to stop or switch should balance how well omeprazole is controlling your reflux or ulcer symptoms against the impact of the headaches. ^{[4] [3]}

Other important considerations

• Headache risk does not seem to increase with typical dose ranges (10–60 mg/day), and dose‑related adverse effects have not been a consistent finding in reviews. ^[3]
• Official consumer information lists headache as one of the “most common” side effects in both adults and children, consistent with trial data. ^[5]
• If you have other symptoms like low magnesium signs (muscle cramps, palpitations), that would be a different safety consideration during longer‑term therapy and warrants checking with your clinician. ^[5]

Bottom line

• Yes, omeprazole can cause headaches, and this occurs in about 7% of users in clinical studies. ^[1]
• Most headaches are mild and temporary, and can often be managed with hydration, rest, and occasional acetaminophen if suitable. ^[3]
• Contact your clinician if headaches are severe, persistent, or accompanied by warning signs, or if you need guidance on adjusting therapy or trying alternatives. ^[4]

Would you like help deciding whether to adjust your dose timing or consider an alternative based on when your headaches occur?