Omeprazole vs famotidine: heartburn medicines compared
Omeprazole (Prilosec) and famotidine (Pepcid) both reduce stomach acid, but in different ways. Omeprazole suppresses acid more strongly and for longer, which suits ongoing reflux and ulcers; famotidine works faster for occasional heartburn and has fewer long-term concerns.
Updated October 4, 2026
At a glance
- Strength
- Omeprazole
- Stronger, longer-lasting acid suppression
- Famotidine
- Moderate acid reduction
- Speed
- Omeprazole
- Takes a few days for full effect
- Famotidine
- Works within about an hour
- Typical use
- Omeprazole
- Frequent reflux, erosive esophagitis, ulcers, H. pylori treatment
- Famotidine
- Occasional heartburn, prevention before meals, milder reflux
- Over the counter
- Omeprazole
- Yes, as a 14-day course
- Famotidine
- Yes
- Generic
- Omeprazole
- Yes
- Famotidine
- Yes
Omeprazole Prilosec, a proton pump inhibitor | Famotidine Pepcid, an H2 blocker | |
|---|---|---|
| Strength | Stronger, longer-lasting acid suppression | Moderate acid reduction |
| Speed | Takes a few days for full effect | Works within about an hour |
| Typical use | Frequent reflux, erosive esophagitis, ulcers, H. pylori treatment | Occasional heartburn, prevention before meals, milder reflux |
| Over the counter | Yes, as a 14-day course | Yes |
| Generic | Yes | Yes |
Choosing between them
For heartburn on two or more days a week, or for healing an inflamed esophagus or an ulcer, a proton pump inhibitor such as omeprazole is usually more effective, taken 30 to 60 minutes before breakfast. For occasional heartburn, or to prevent it before a meal you know will trigger it, famotidine works faster and is taken 15 to 60 minutes before eating. Heartburn that persists, returns quickly after a course, or comes with trouble swallowing, weight loss or black stools needs a clinician.
Long-term use
Long-term proton pump inhibitor use has been linked to lower vitamin B12 and magnesium, fractures and some infections, so prescribers aim for the lowest dose that controls symptoms. Famotidine has fewer long-term concerns, though the dose is lowered in reduced kidney function and older adults can occasionally become confused. Omeprazole reduces the effect of the blood thinner clopidogrel; famotidine does not.
Cost
Both are inexpensive generics and are sold over the counter, where store-brand versions are the same medicine as the name brands. Prescription and over-the-counter prices can differ, so compare both if you take either regularly.
Over-the-counter use
Over-the-counter omeprazole is taken once a day for 14 days, no more than three courses a year, and is not meant for immediate relief. Over-the-counter famotidine can be taken up to twice a day when needed. If you need either for longer or more often, see a clinician, because frequent heartburn can signal a condition that needs different treatment.
Questions for your prescriber
- Do my symptoms need a proton pump inhibitor, or would famotidine be enough?
- How long should I take it, and how should I stop?
- Do any of my other medicines interact, such as clopidogrel?
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Sources
Written by the Script Unlock editorial team from the sources above. It is general information, not advice for you or your pet; your prescriber decides which medicine is right.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.