Key takeaways:
Famotidine (Pepcid AC) and omeprazole (Prilosec OTC) are two medications used to treat gastroesophageal reflux disease (GERD). Famotidine is a histamine-2 antagonist (H2 blocker), while omeprazole is a proton pump inhibitor (PPI).
Famotidine lowers acid production quickly. Omeprazole takes longer to work but provides longer-lasting relief.
Omeprazole is generally more effective for GERD than famotidine. But these medications have different side effects and interactions. This may determine which is a better fit for you.
Omeprazole and famotidine are both available as lower-cost generics. GoodRx can help you save over 80% off the average retail price at certain pharmacies.
Save on related medications
Have you ever experienced a burning sensation in your chest, especially after eating a spicy or fried meal? Or maybe you felt the food you just ate traveling back up from your stomach? These are typical symptoms of acid reflux. And if they happen twice a week or more, you may have gastroesophageal reflux disease (GERD).
Famotidine (Pepcid AC) and omeprazole (Prilosec OTC) are two acid-blocking medications that can help keep your GERD symptoms at bay. But when comparing famotidine versus omeprazole, is one better than the other? Let’s look at six similarities and differences between these medications.
1. Famotidine and omeprazole work differently to treat GERD
Famotidine is a histamine-2 antagonist (H2 blocker) medication. You may be familiar with the role histamine plays when it comes to allergies. But histamine also stimulates the production of stomach acid. Famotidine blocks the effects of histamine, which helps lower the amount of acid made by your stomach.
Search and compare options
Omeprazole, on the other hand, is a proton pump inhibitor (PPI). Omeprazole works by blocking an enzyme (protein) that releases acid into the stomach. These enzymes are referred to as proton pumps.
2. Famotidine and omeprazole come in different doses and dosage forms
Both famotidine and omeprazole work best if you take them on an empty stomach, about an hour before eating. But there are differences between their recommended doses and available dosage forms.
Famotidine is available by prescription as a tablet, an oral suspension (liquid), and an injection. You can also find it as an over-the-counter (OTC) tablet.
The typical famotidine dosage for GERD in adults is 20 mg twice a day. Your prescriber may recommend a different dosage for other health conditions. Famotidine is also safe for infants and children, but you shouldn’t give it to children under age 12 without a healthcare professional’s OK.
Omeprazole is available by prescription as a capsule and powder packets that form an oral suspension when mixed with liquid. You can also find it OTC as tablets or capsules.
The typical omeprazole dosage for GERD in adults is 20 mg once daily. It’s also approved for children ages 1 and older. But you shouldn’t give omeprazole to children without a healthcare professional’s OK.
Good to know: The OTC forms of famotidine and omeprazole are only approved for occasional heartburn. You shouldn’t take them for more than 2 weeks at a time without a healthcare professional’s OK.
3. Famotidine starts working faster, but omeprazole’s effects last longer
Famotidine reaches its peak effect about 1 to 3 hours after taking it. The effects typically last for about 10 to 12 hours, which is why you’ll need to take it twice a day in most cases.
Omeprazole starts reducing stomach acid within an hour of taking it. But it can take up to 4 days for it to reach its full effect. This is because omeprazole blocks only active proton pumps. And your body is constantly making new ones. So it can take a few days to block enough pumps to keep stomach acid under control.
But omeprazole’s effects last much longer than famotidine’s. It remains effective for up to 72 hours after taking it. Famotidine may also stop working as well over time as your body gets used to the medication. But this doesn’t seem to be the case with omeprazole.
Take our quiz: Acid reflux medications?
4. Omeprazole is considered more effective than famotidine for GERD
Research has shown that omeprazole and other PPIs are preferred over famotidine and other H2 blockers for GERD. This is because PPIs reduce stomach acid and let the esophagus heal better than H2 blockers do.
That being said, famotidine is also FDA approved to treat GERD. So it’s still an effective option. Your prescriber will help determine the best treatment for you based on your personal history.
Keep in mind that making lifestyle changes are just as important as medications when it comes to managing GERD symptoms. These include:
Maintaining a healthy body weight
Elevating your head while sleeping
Avoiding fried, acidic, and fatty foods
Eating smaller meals throughout the day
Avoiding smoking
Avoiding or limiting alcohol
5. Famotidine and omeprazole have different side effects
Famotidine and omeprazole are typically well-tolerated when taken as directed. But as with any medication, side effects are possible. Both medications may cause:
Stomach pain
Nausea and vomiting
In addition to the above, famotidine can cause agitation, especially in infants. Gas and flatulence was reported with omeprazole but not with famotidine.
Famotidine and omeprazole can also both cause acid rebound. Acid rebound is when your stomach temporarily starts making more acid after you stop taking an acid-blocking medication. Your prescriber may slowly lower your dose or switch you to a different medication to minimize this effect.
What are the serious side effects of famotidine and omeprazole?
Serious side effects are rare, but they’re possible with either medication.
Serious famotidine side effects include confusion, agitation, and seizures. These side effects are more likely in older adults or those with kidney problems. The American Geriatrics Society recommends avoiding famotidine if you’re an older adult with a history of kidney problems or delirium (confusion).
Serious omeprazole side effects include kidney problems, new or worsening lupus, and Clostridioides difficile (C. diff) diarrhea.
Taking omeprazole long term can also affect how your body absorbs some vitamins and minerals. This may lead to vitamin B12 deficiency, low magnesium, and a higher risk of bone fractures (breaks). Taking PPIs long term has also been linked to a higher risk of dementia and heart disease in some studies.
6. Famotidine and omeprazole have different drug interactions
Famotidine and omeprazole both have drug interactions to consider. One of these medications may be a better option for you based on the other medications you’re taking.
Famotidine and omeprazole lower the amount of acid in your stomach. As a result, both can affect how well your body absorbs other medications. Examples include:
Oral ketoconazole
Some cancer medications, such as dasatinib (Sprycel, Phyrago)
Certain HIV medications, such as atazanavir (Reyataz)
In addition, famotidine may interact with tizanidine (a muscle relaxer). This combination is typically avoided.
Omeprazole, on the other hand, has several other interactions to consider. Examples include:
Clopidogrel (Plavix)
Warfarin (Coumadin, Jantoven)
Digoxin (Lanoxin)
Diazepam (Valium)
Methotrexate (Trexall, Xatmep)
Citalopram (Celexa)
Keep in mind that these examples don’t include all possible interactions. Make sure your healthcare team checks your current medication list for any issues before you take either medication.
How to save on famotidine and omeprazole
Famotidine and omeprazole are both available as lower-cost generics. GoodRx can help you save over 80% off the average retail price of the generic versions. The price of 60 famotidine 20 mg tablets at certain pharmacies is as low as $6.60 with a free GoodRx discount. The price of 30 omeprazole 20 mg capsules at certain pharmacies is as low as $9.30 with a free GoodRx discount.
You can also save on the cost of OTC versions of these medications. But you’ll need a prescription from a healthcare professional first. With a free GoodRx discount, you can get 60 tablets of OTC famotidine 10 mg for as low as $18.25, and 30 tablets of OTC omeprazole 20 mg for as low as $20.34.
Save with GoodRx Companion
You can access discounted prescription and OTC medications with a GoodRx Companion subscription. Over 200 medications — including some forms of omeprazole and famotidine — are available for free, with hundreds more for under $10. The subscription also includes benefits to help you cut your self-pay costs, such as lower prices for online care visits, discounts on dental care, and other health services.
Frequently asked questions
Yes, with a healthcare professional’s OK. There are certain situations when your prescriber may recommend taking both omeprazole and famotidine. Most people have success treating GERD symptoms with just PPIs. But some people may still have heartburn, especially at night. In that case, your prescriber may recommend adding famotidine or another H2 blocker at bedtime to help manage nighttime symptoms. But you shouldn’t combine these medications on your own.
There isn’t one acid-reducing treatment that’s considered safest for everyone, regardless of whether you’re taking it short term or long term. They all have risks, which can vary from person to person. It’s generally best to take these medications for the shortest amount of time possible. But if your prescriber recommends taking them long term, it’s likely that the risks of the medication are lower than the risks of leaving your health condition untreated. Your prescriber can help you determine the best acid-reducing option based on your personal history.
Yes, it’s possible to switch from omeprazole to famotidine. You can take either medication occasionally for heartburn. But omeprazole and other PPIs are the preferred treatment for GERD. So if you’re treating GERD, it’s best to make this switch only if your prescriber recommends it.
Yes, with a healthcare professional’s OK. There are certain situations when your prescriber may recommend taking both omeprazole and famotidine. Most people have success treating GERD symptoms with just PPIs. But some people may still have heartburn, especially at night. In that case, your prescriber may recommend adding famotidine or another H2 blocker at bedtime to help manage nighttime symptoms. But you shouldn’t combine these medications on your own.
There isn’t one acid-reducing treatment that’s considered safest for everyone, regardless of whether you’re taking it short term or long term. They all have risks, which can vary from person to person. It’s generally best to take these medications for the shortest amount of time possible. But if your prescriber recommends taking them long term, it’s likely that the risks of the medication are lower than the risks of leaving your health condition untreated. Your prescriber can help you determine the best acid-reducing option based on your personal history.
Yes, it’s possible to switch from omeprazole to famotidine. You can take either medication occasionally for heartburn. But omeprazole and other PPIs are the preferred treatment for GERD. So if you’re treating GERD, it’s best to make this switch only if your prescriber recommends it.
The bottom line
Famotidine (Pepcid AC) and omeprazole (Prilosec OTC) are two medications that treat gastroesophageal reflux disease (GERD). Both are available in prescription and over-the-counter forms. But they work differently to lower stomach acid. And omeprazole is typically preferred over famotidine for treating GERD.
Omeprazole and famotidine have different side effects and drug interactions to consider. These differences may make one a better treatment option than another based on your personal history. Your prescriber can help you determine the best treatment option for your needs.
Why trust our experts?
References
Ahmed, A., et al. (2023). Proton pump inhibitors (PPI). StatPearls.
Ascend Laboratories, LLC. (2025). Famotidine- famotidine powder, for suspension [package insert].
Briganti, S. I., et al. (2021). Proton pump inhibitors and fractures in adults: A critical appraisal and review of the literature. International Journal of Endocrinology.
Covis Pharma U.S. (2024). Prilosec- omeprazole magnesium granule, delayed release [package insert].
Day, J., et al. (2017). Histamine: The stuff allergies are made of [video]. MedlinePlus.
Glenmark Therapeutics. (2026). Famotidine tablet, film coated [package insert]. DailyMed.
Goosenberg, E., et al. (2025). Gastroesophageal reflux disease (GERD). StatPearls.
Katz, P. O., et al. (2001). Histamine receptor antagonists, proton pump inhibitors and their combination in the treatment of gastro-oesophageal reflux disease. Best Practice & Research Clinical Gastroenterology.
Kinoshita, Y., et al. (2018). Advantages and disadvantages of long-term proton pump inhibitor use. Journal of Neurogastroenterology and Motility.
McRorie, J. W., et al. (2014). Histamine2-receptor antagonists: Rapid development of tachyphylaxis with repeat dosing. World Journal of Gastrointestinal Pharmacology and Therapeutics.
Medical Purchasing Solutions, LLC. (2026). Famotidine- famotidine injection, solution [package insert].
Marksans Pharma Limited. (2026). Omeprazole 20 mg tablet, delayed release [package insert]. DailyMed.
National Institute of Diabetes and Digestive and Kidney Diseases. (2020). Treatment for GER & GERD. National Institutes of Health.
Nguyen, K., et al. (2024). Famotidine. StatPearls.
Nugent, C. C., et al. (2024). H2 blockers. StatPearls.
Patel, D., et al. (2019). A systematic review of gastric acid-reducing agent-mediated drug-drug interactions with orally administered medications. Clinical Pharmacokinetics.
PD-Rx Pharmaceuticals, Inc. (2026). Famotidine- famotidine tablet, film coated [package insert].
Remedyrepack, Inc. (2026). Omeprazole- omeprazole capsule, delayed release [package insert].
Samuel, M. J. (2023). American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society.
Shah, N., et al. (2023). Omeprazole. StatPearls.
The ASGE Standards of Practice Committee. (2025). American Society for Gastrointestinal Endoscopy guideline on the diagnosis and management of GERD: Summary and recommendations. Gastrointestinal Endoscopy.
Walgreen Company. (2025). Omeprazole capsule, delayed release [package insert]. DailyMed.
