Famotidine vs. Omeprazole: Which Works Best for GERD?

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) 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.

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 doses and 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 under age 18 without a healthcare professional’s OK.

Good to know: The OTC forms of famotidine and omeprazole are approved to treat only occasional heartburn. You should take them for only up to 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 in 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.

EXPERT PICKS: WHAT TO READ NEXT

• Eat right for heartburn. Preventing acid reflux starts with avoiding foods more likely to trigger heartburn.

• Don’t ignore acid reflux. Chronic heartburn can be a sign of more serious medical conditions.

• What does heartburn feel like? Read about several firsthand experiences and how their symptoms differ.

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 treatment option. Your prescriber will help you 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

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:

• Headache

• Stomach pain

• Nausea and vomiting

• Diarrhea

• Constipation

• Dizziness

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.

Long-term omeprazole use can also affect how your body absorbs 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)

• 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)

• St. John’s wort

• 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. Generic famotidine’s price at certain pharmacies is as low as $6.60 with a free GoodRx discount. Generic omeprazole’s price at certain pharmacies is as low as $5.88 with a free GoodRx discount.

You can also save on the cost of the OTC versions of these medications. But you’ll need a prescription from a healthcare professional. With a free GoodRx discount, you can get a 30-day supply of OTC famotidine for as low as $7.15, and OTC omeprazole for as low as $10.81.

Frequently asked questions

Why trust our experts?

Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Our editorial standards

Meet our experts