Omeprazole (Prilosec, Losec)
A proton pump inhibitor that dramatically reduces stomach acid. Very effective for reflux and ulcers — but long-term use has some considerations worth knowing.
What it's used for
GERD (acid reflux), gastric and duodenal ulcers, H. pylori eradication (with antibiotics), Zollinger-Ellison syndrome, and NSAID-induced ulcer prevention.
Typical dosing (adults)
- OTC: 20mg once daily for 14 days (heartburn).
- Prescription: 20-40mg once daily; higher for certain conditions.
- Timing: take 30-60 minutes before the first meal of the day. Swallow capsules whole.
Key interactions
- Clopidogrel (Plavix): moderate-major — may reduce clopidogrel's antiplatelet effect; consider pantoprazole instead.
- Methotrexate (high dose): moderate — raised levels.
- Certain HIV drugs (rilpivirine, atazanavir): major — reduced absorption.
- Iron, vitamin B12, calcium: long-term PPI use can reduce absorption.
- Warfarin, digoxin, phenytoin: monitor.
Long-term use considerations
Most people do fine on long-term PPIs, but association studies link extended use with: B12 deficiency, magnesium depletion, possible increased fracture risk, possible increased risk of C. difficile infection. Periodically review with your doctor whether you still need it.
Common side effects
Headache, abdominal pain, nausea, diarrhea, constipation. Rarely: rash, dizziness. Long-term: as above.
Who should be cautious
- On clopidogrel (consider alternative PPI).
- History of osteoporosis.
- Long-term high-dose use without periodic review.
What to ask your pharmacist
- Is omeprazole compatible with my antiplatelet therapy?
- How long should I stay on it?
- Should I have my B12 or magnesium checked?
- Can I step down to an H2 blocker (famotidine)?