Famotidine (Pepcid AC) is a histamine-2 (H2) antagonist that's used to treat conditions that cause too much stomach acid to build up, such as heartburn and stomach or intestinal ulcers (sores). It starts to work within an hour and lasts for several hours. It's available as a tablet and a liquid, and is taken by mouth twice per day. Side effects of famotidine (Pepcid AC) include headache, dizziness, and constipation.
Over-the-counter (OTC) famotidine
Prescription famotidine
Famotidine (Pepcid AC) is a histamine-2 (H2) antagonist. It works by lowering the amount of stomach acid released by certain cells in the lining of your stomach.
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
Rare
Abdominal pain
back, leg, or stomach pain
bleeding or crusting sores on lips
blistering, burning, redness, scaling, or tenderness of skin
blisters on palms of hands and soles of feet
changes in vision or blurred vision
confusion
coughing or difficulty in swallowing
dark-colored urine
dizziness
fainting
fast, pounding, or irregular heartbeat
fever and/or chills
flu-like symptoms
general feeling of discomfort or illness
inflammation of blood vessels
joint pain
light-colored stools
mood or mental changes, including anxiety, agitation, confusion, hallucinations (seeing, hearing, or feeling things that are not there), mental depression, nervousness, or severe mental illness
muscle cramps or aches
nausea, vomiting, or loss of appetite
peeling or sloughing of skin
red or irritated eyes
shortness of breath
skin rash or itching
slow heartbeat
sores, ulcers, or white spots on lips, in mouth, or on genitals
sudden difficult breathing
swelling of face, lips, mouth, tongue, or eyelids
swelling of hands or feet
swollen or painful glands
tightness in chest
troubled breathing
unusual bleeding or bruising
unusual tiredness or weakness
unusually slow or irregular breathing
yellow eyes or skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common or rare
decrease in sexual desire
decreased sexual ability (especially in patients with Zollinger-Ellison disease who have received high doses of cimetidine for at least 1 year)
difficult urination
dizziness
drowsiness
dryness of mouth or skin
headache
increased or decreased urination
increased sweating
loss of hair
ringing or buzzing in ears
swelling of breasts or breast soreness in females and males
trouble in sleeping
Not all of the side effects listed above have been reported for each of these medicines, but they have been reported for at least one of them. All of the H2-blockers are similar, so any of the above side effects may occur with any of these medicines.
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More tips for the oral suspension (liquid) only:
More tips for over-the-counter famotidine (Pepcid AC) only:
Famotidine (Pepcid AC) is one of the commonly prescribed treatment options for heartburn, but it might not be the best choice depending on how severe your condition is. The 2022 heartburn treatment guidelines recommends another class of heartburn medications called proton pump inhibitors (PPIs) over famotidine (Pepcid AC) for people with erosive esophagitis. This is because studies show that people who take PPIs have a faster healing rate and more complete heartburn relief compared to people who take famotidine (Pepcid AC). But, H2 antagonists are still one of the backbone treatment options for heartburn because they've been shown to work well in several studies. Your provider will decide if famotidine (Pepcid AC) is right for you based on your symptoms and cause(s) of heartburn. Read this article for learn more about the different medication options for heartburn.
Zantac 75 and Zantac 150 were brands of ranitidine, an H2-blocker similar to famotidine (Pepcid AC). Ranitidine was removed from the market in April 2020 by the FDA. This happened because a long investigation showed there were detectable levels of a potential cancer-causing chemical (called nitrosamines) in ranitidine (Zantac) products. As a result of the immediate removal of all ranitidine (Zantac) products, the manufacturer of ranitidine (Zantac) released [Zantac 360] into the market, which contains famotidine (Pepcid AC) instead of ranitidine. There are no clear differences between Pepcid and Zantac 360 - both are brand names of famotidine.
Talk with your provider if you think famotidine (Pepcid AC) alone isn't enough for your heartburn symptoms. Omeprazole (Prilosec) is a proton pump inhibitor (PPI), another class of medication that can help treat heartburn symptoms. Famotidine (Pepcid AC) and omeprazole (Prilosec) aren't typically taken together. But there are certain situations where your provider might recommend adding famotidine (Pepcid AC) to omeprazole (Prilosec). For example, if your heartburn symptoms aren't relieved by omeprazole (Prilosec) and get worse at night, your provider might recommend for you to take famotidine (Pepcid AC) at bedtime, as needed.
Based on available data about human pregnancy, there isn't a clear link between famotidine (Pepcid AC) and birth defects or pregnancy-related problems, such as early labor. American Academy of Family Physicians (AAFP) considers famotidine (Pepcid AC) a probably safe option for pregnant females, but more data is needed. If you're pregnant, discuss with your provider about the risks and benefits of taking famotidine (Pepcid AC) before using to make sure it's safe for you and your unborn baby.
Yes, famotidine (Pepcid AC) is generally considered safe during breastfeeding. While some of the medication does get into breastmilk, the amount is low and wouldn't be expected to cause any harm to your baby. But, to be safe, always discuss with your provider about the risks and benefits of taking famotidine (Pepcid AC) while breastfeeding.
Famotidine (Pepcid AC) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Famotidine (Pepcid AC) can cause certain brain-related side effects, such as confusion, delirium, hallucinations (seeing things that aren't real), agitation, seizures, and weakness. The risk is higher in people with kidney problems because it's more difficult for their kidneys to metabolize (break down) famotidine (Pepcid AC), which raises the blood levels of famotidine (Pepcid AC) and can cause side effects. If you've kidney problems, your provider might lower your dose of famotidine (Pepcid AC). Talk to your provider if you have kidney problems and are interested in taking famotidine (Pepcid AC).
Rarely, heartburn can be warning signs of a more serious stomach problem or cancer. Sometimes, taking heartburn medications, like famotidine (Pepcid AC), can mask these warning signs. If your heartburn symptoms don't go away after you've completed treatment with famotidine (Pepcid AC), contact your provider. You might need to undergo testing to see if you have a more serious problem like stomach cancer.
Over-the-counter (OTC):
OTC famotidine is available as 10 mg and 20 mg tablets.
Adults and children age 12 years and older
Children younger than 12 years old
Prescription:
Prescription famotidine is available as 20 mg and 40 mg tablets, and a liquid suspension.
Adults and children (who weigh 88 lbs or more)
Children (famotidine oral suspension only)
Your child's provider will determine your child's dose based on their body weight.
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.
Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Famotidine (Pepcid AC) will not be safe for you to take.
Over-the-counter (OTC) famotidine
Prescription famotidine