December 9, 2023

What Is Pepcid AC?

Pepcid AC (famotidine) is an over-the-counter (OTC) drug used to prevent or relieve heartburn associated with acid indigestion and sour stomach (caused by consuming particular food and drinks).

This medication works by lowering acid production in the stomach. Pepcid AC is in a drug class known as histamine H2-receptor antagonists, H2 receptor antagonists, or H2 blockers.

Original Strength Pepcid AC is available as a tablet that contains 10 milligrams (mg) of famotidine. The drug is also available as Maximum Strength Pepcid AC, containing 20 milligrams of famotidine per tablet. Pepcid also comes in prescription form as 20 milligrams or 40 milligrams of famotidine. Prescription Pepcid has some additional indications, but this article will focus on OTC Pepcid AC.

Drug Facts

Generic Name: Famotidine

Brand Name(s): Pepcid AC, Pepcid, Heartburn Relief

Administration Route(s): Oral

Drug Availability: Over the counter (OTC) or prescription

Therapeutic Classification: Histamine H2 antagonist

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Famotidine

Dosage Form(s): Tablet, powder for suspension

What Is Pepcid AC Used For?

OTC Pepcid AC prevents or relieves heartburn caused by acid indigestion and sour stomach from eating or drinking certain foods and beverages.

The prescription form of Pepcid is approved to treat adults and children 40 kilograms and above with:

  • Active duodenal ulcer
  • Active gastric ulcer
  • Symptomatic non-erosive gastroesophageal reflux disease (GERD)
  • Erosive esophagitis due to GERD

It can also be used, with a prescription from a healthcare provider, to treat pathological hypersecretory conditions (such as Zollinger-Ellison Syndrome) and reduce the risk of duodenal ulcer recurrence.

How to Take Pepcid AC

Before taking Pepcid AC, read the directions on the package. Ask your healthcare provider if you have any questions. 

Pepcid AC can be used by adults and children 12 years and older. When taking Pepcid AC to relieve symptoms, swallow the tablet whole (do not chew) with a glass of water. 

If you are taking Pepcid AC to prevent symptoms, swallow the tablet whole (do not chew) with a glass of water between 15 and 60 minutes before eating food or drinking a beverage that causes symptoms. Do not use more than two tablets in 24 hours.

If you are taking prescription Pepcid, take your dose once daily before bedtime or twice daily in the morning and before bedtime, as recommended by your healthcare provider.


Pepcid AC should be stored at room temperature (68 degrees and 77 degrees Fahrenheit), away from heat, direct light, and moisture. Keep Pepcid AC out of the reach of children and pets.

How Long Does Pepcid AC Take to Work?

A dose of Pepcid AC starts working in 15 to 30 minutes.

What Are the Side Effects of Pepcid AC?

This is not a complete list of side effects and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at or 1-800-FDA-1088.

Common Side Effects

The most common side effects of Pepcid AC are:

  • Headache 
  • Dizziness
  • Constipation or diarrhea
  • Altered taste

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Hypersensitivity reaction or anaphylaxis: Symptoms can include rash, hives, swelling around the lips, tongue, and face, and difficulty breathing
  • Angioedema (swelling under the skin)
  • Stevens-Johnson syndrome or toxic epidermal necrolysis (life-threatening skin reactions): Symptoms may include fever, red or purple rash, and blistering or peeling skin)
  • Low red and/or white blood cells 
  • Low platelet levels 
  • Seizures 
  • Heart or heart rhythm problems 
  • Liver problems: Symptoms may include tiredness, upper abdominal pain, dark urine, clay-colored stools, and yellowing of the skin or whites of eyes
  • Lung problems

Long-Term Side Effects

Some people have long-term side effects from taking famotidine. Some long-term side effects can be mild, such as:

  • Appetite loss
  • Numbness and tingling
  • Anxiety
  • Sexual problems
  • Dry skin
  • Acne
  • Hair loss
  • Muscle or joint pain
  • Ringing in the ears
  • Weakness
  • Infection

Males may also have swollen breast tissue.

Moderate long-term side effects can include: 

Other long-term side effects can be very serious, such as life-threatening skin reactions, seizures, and low levels of red and/or white blood cells.

Dosage: How Much Pepcid AC Should I Take?

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IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (suspension, tablets):

    • To prevent an ulcer from coming back:

      • Adults—20 milligrams (mg) once a day.
      • Children—Use and dose must be determined by your doctor.
    • To treat erosive esophagitis (heartburn):

      • Adults and children weighing 40 kilograms (kg) or more—20 milligrams (mg) 1 or 2 times per day, at the morning and at bedtime, or 40 mg once a day at bedtime for up to 12 weeks.
      • Children weighing less than 40 kg—Use and dose be determined by your doctor.
    • To treat gastroesophageal reflux disease (GERD):

      • Adults and children weighing 40 kilograms (kg) or more—20 milligrams (mg) 2 times per day, in the morning and at bedtime for up to 6 weeks.
      • Children weighing less than 40 kg—Use and dose be determined by your doctor.
    • To treat stomach ulcers:

      • Adults and children weighing 40 kilograms (kg) or more—20 milligrams (mg) 2 times per day, at the morning and at bedtime, or 40 mg once a day at bedtime for up to 8 weeks.
      • Children weighing less than 40 kg—Use and dose be determined by your doctor.
    • To treat too much stomach acid (Zollinger-Ellison syndrome):

      • Adults—20 milligrams (mg) every 6 hours. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.


Certain factors may require you to take precautions or change your dosing regimen when using Pepcid AC. These may include:

  • Pregnancy or breastfeeding: If you are pregnant or breastfeeding, consult your healthcare provider before taking Pepcid AC.
  • Age: Famotidine may cause more side effects in adults aged 65 and older, especially in those who also have kidney problems. Consult your provider before using Pepcid AC. 
  • Kidney problems: People with moderate to severe kidney problems usually need to take a lower dose of famotidine. Consult your healthcare provider for medical advice.

Missed Dose

If your healthcare provider has recommended you take your medication regularly, take the missed dose as soon as you remember it. Skip the missed dose and resume your regular dosing schedule if it is almost time for the next dose. Do not double up on doses if you miss a dose. 

Overdose: What Happens If I Take Too Much Pepcid AC?

Symptoms of taking too much Pepcid AC may be similar to the usual side effects including:

  •  Headache
  • Dizziness
  • Stomach problems
  • Altered taste

What Happens If I Overdose on Pepcid AC?

If you think you or someone else may have overdosed on Pepcid AC, call a healthcare provider or the Poison Control Center (1-800-222-1222).

If someone collapses or isn’t breathing after taking Pepcid AC, call 911 immediately.


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IBM Micromedex®

It is very important that your doctor check your or your child’s progress at regular visits to make sure this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

If your condition does not improve, or if it become worse, check with your doctor.

Check with your doctor right away if you have the following symptoms: confusion, delirium, hallucinations, disorientation, agitation, seizures, or unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness. These are more likely to occur if you are older or if you have a kidney disease.

Contact your doctor right away if you have any changes to your or your child’s heart rhythm. You or your child might feel dizzy or faint, or you or your child might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you had a heart rhythm problem, such as QT prolongation.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Pepcid AC?

Pepcid AC is not appropriate for everyone. You should not take Pepcid AC if you are allergic to famotidine or any of the inactive ingredients. If you have pain or difficulty swallowing food, or if you have vomiting with blood, or have bloody or black stools, this can be a serious condition. See a healthcare provider.

Pepcid AC should not be taken with other H2 blockers.

Check with your provider before taking Pepcid AC if you have:

  • Had heartburn symptoms for more than three months
  • Heartburn accompanied by sweating, lightheadedness, or dizziness
  • Chest or shoulder pain with shortness of breath; sweating; pain that spreads to the arms, neck, or shoulders; lightheadedness
  • Frequent chest pain
  • Wheezing 
  • Unexplained weight loss
  • Stomach pain, nausea, or vomiting
  • Kidney problems 

If you already take Pepcid AC, stop and consult your provider if:

  • The pain continues or worsens, or 
  • You need to take the medicine for more than two weeks. 

What Other Medications Interact With Pepcid AC?

Ask your healthcare provider if it is safe to take Pepcid AC with the other medications you take (including prescription and OTC drugs, as well as vitamins and supplements).

Drugs that may interact with Pepcid AC include, but are not limited to:

  • Reyataz (atazanavir) 
  • Capoten (captopril) 
  • Cefpodoxime 
  • Zinacef (cefuroxime) 
  • Spyrcel (dasatinib) 
  • Dexedrine, Dexotrostat, Liquadd, ProCentra, Zenzedi (dextroamphetamine) 
  • Tarceva (erlotinib) 
  • Ferrous gluconate or sulfate
  • Monopril (fosinopril) 
  • Truseltiq (infigratinib) 
  • Nizoral (ketoconazole) 
  • Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid (levothyroxine)
  • Ponstel (mefenamic acid)
  • Apriso, Asacol HD, Delzicol, Lialda, Pentasa (mesalamine)
  • Aptensio XR, Concerta, Cotempla XR-ODT, Ritalin, among other brand names (methylphenidate)
  • Votrient (pazopanib) 
  • Retevmo (selpercatinib)
  • Lumakras (sotorasib) 
  • Zanaflex (tizanidine) 
  • Halcion (triazolam) 

What Medications Are Similar?

Besides Pepcid AC, other H2 blockers that are available OTC include:

  • Pepcid Complete (contains famotidine and the antacids calcium carbonate and magnesium hydroxide)
  • Tagamet HB (cimetidine)

Prescription H2 blockers include:

  • Axid (nizatidine)
  • Pepcid (famotidine) 
  • Tagamet (cimetidine)

Another popular class of drugs used to treat GERD or ulcers is called proton pump inhibitors, or PPIs. PPIs work by reducing acid production. These include:

This list is a list of drugs also prescribed for stomach conditions. It is NOT a list of drugs recommended to take with Pepcid AC. Ask your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • What is Pepcid AC used for?

    Pepcid AC prevents or relieves heartburn caused by indigestion or sour stomach from certain foods and drinks.

  • How does Pepcid AC work?

    Pepcid AC works by decreasing the amount of acid made in the stomach. This helps prevent or relieve heartburn symptoms.

  • What drugs should not be taken with Pepcid AC?

    Before taking Pepcid AC, ask your healthcare provider if it is compatible with the other medicines you take. Some drugs should be avoided when taking Pepcid AC (see above section for more information).

  • How long does it take for Pepcid AC to work?

    A dose of Pepcid AC starts working within 15 to 30 minutes.

  • What are the side effects of Pepcid AC?

    The most common side effects of Pepcid AC are headache, dizziness, altered taste, and nausea or constipation.

  • How do I safely stop taking Pepcid AC?

    Your healthcare provider will advise you on how long to take Pepcid AC and when to stop.

How Can I Stay Healthy While Taking Pepcid AC?

Tell your healthcare provider about your symptoms, current medical conditions, and medical history before starting Pepcid AC. Bring a list of the medications you take, including all prescription and OTC drugs, vitamins, and supplements, to review with your provider. You can also ask your healthcare provider if any of the medications you take are contributing to your heartburn symptoms.

You may also want to consider dietary factors, such as what foods or beverages could be aggravating your symptoms. 

Foods you may want to avoid include:

  • Caffeine and carbonated drinks such as soda
  • Certain spices such as chili and cayenne pepper
  • Cheese
  • Chocolate
  • Citrus fruits (e.g., oranges, grapefruit)
  • Fast food
  • Fried food
  • Meats that contain a lot of fat, like sausage and bacon
  • Peppermint 
  • Pizza
  • Processed snacks like potato chips
  • Tomato sauces and tomato juice

Eating smaller meals, and eating slowly may help as well. Additionally, try to stay upright after eating. Don’t eat before you go to bed. Consult a registered dietician if you need help with a diet that avoids heartburn-triggering foods. 

Other lifestyle changes that may help symptoms of heartburn include:

  • Propping your head up while sleeping or using bed risers to position your head 6 to 8 inches higher than your feet
  • Losing weight if needed 
  • Stopping smoking

Medical Disclaimer

Verywell Health’s drug information is meant for education purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.


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