Cimetidine

Introduction

Written by Kirstyn Hill, PharmD, MPH
Medically reviewed by Patricia Weiser, PharmD
Updated on September 13, 2023

Cimetidine (sye MET i deen) is a generic medication prescribed for certain conditions that cause heartburn and acid reflux. Cimetidine belongs to a group of drugs called histamine-2 receptor blockers.

This article doesn’t provide coupons for all forms of cimetidine. To find coupons for cimetidine oral solution, see this article.

Side effects of cimetidine

Cimetidine may cause mild or serious side effects. More common mild side effects of cimetidine and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about cimetidine’s side effects, ask your doctor or pharmacist. You can also refer to the prescribing information for cimetidine listed in the “Resources” section.

Mild side effects

More common mild side effects reported with some forms of cimetidine are listed below.

This article doesn’t include all possible mild side effects of the drug. To learn more about cimetidine’s side effects based on the form, refer to the prescribing information for cimetidine listed in the “Resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Mild side effects of cimetidine oral tablet and oral solution include:

• diarrhea
• headache
• dizziness
• enlarged breast tissue in males*
• mild allergic reaction†

* Sex and gender exist on spectrums. In this article, we use the term “male” to refer to a person’s sex assigned at birth.
† For details about this side effect, see the “Interactions and warnings for cimetidine” section.

Serious side effects

Serious side effects of cimetidine are listed below.

This article doesn’t include all possible serious side effects of the drug. To learn more about cimetidine’s side effects based on the form, refer to the prescribing information for cimetidine listed in the “Resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, cimetidine’s serious side effects include:

• low level of platelets (a type of blood cell that helps form clots)*
• low level of white blood cells*
• problems with liver function, including high liver enzyme levels
• severe allergic reaction†

* This side effect wasn’t reported in studies of cimetidine oral tablet or oral solution. But it has occurred in people after the drug was approved for use.
† For details about this side effect, see the “Interactions and warnings for cimetidine” section.

Common questions about cimetidine

Below you’ll find answers to a few commonly asked questions about cimetidine.

What brand names are available for cimetidine?

Currently, there are no brand-name versions of prescription cimetidine.

An over-the counter drug called Tagamet HB contains cimetidine as its active drug. (An active drug is the ingredient that makes a medication work.) But its strengths, forms, and uses differ from prescription cimetidine. Tagamet HB helps treat and prevent heartburn due to acid reflux.

A generic medication is an identical copy of the active drug in a brand-name medication. Generic drugs are believed to be as effective and safe as brand-name drugs. And generic drugs usually cost less compared with brand-name drugs. For more information on brand versus generic drugs, see this article.

To learn about the uses of prescription cimetidine, see the “Uses of cimetidine” section. For more information about Tagamet HB, talk with your doctor or pharmacist.

Is cimetidine similar to Zantac?

Yes, it is. Cimetidine and Zantac, the brand-name version of ranitidine, are both histamine-2 (H2) receptor blockers. Both ranitidine and cimetidine were approved by the Food and Drug Administration (FDA) to treat some of the same digestive system conditions by reducing stomach acid. An example is gastroesophageal reflux disease (GERD), which is a severe form of acid reflux.

However, Zantac and generic ranitidine were taken off the market by the FDA due to concerns that the drugs contained harmful chemicals.

Prescription famotidine, another H2 receptor blocker, is available and has similar uses to cimetidine. To find out more about how famotidine compares with cimetidine, ask your doctor or pharmacist.

If you have any questions about how cimetidine compares with ranitidine, famotidine, and other medications for your condition, talk with your doctor or pharmacist.

How does cimetidine work? And how long does it take to start working?

Cimetidine works by blocking H2 receptors in your stomach. These receptors release acid in your stomach. By blocking these receptors, cimetidine helps reduce the amount of acid in your stomach. This helps relieve pain and discomfort caused by the acid. After taking one dose of cimetidine, the drug should start working in 1 hour.

If you’d like to know more about how cimetidine works, talk with your doctor or pharmacist.

Uses of cimetidine

The Food and Drug Administration (FDA) approves prescription drugs such as cimetidine for certain conditions. Approved uses for cimetidine are described below.

Use for certain digestive conditions

Doctors may prescribe cimetidine oral tablet or oral solution for treating certain digestive conditions. It’s used for this purpose in adults and children ages 16 years and older.

Cimetidine is prescribed to:

• treat sudden duodenal ulcers (sores in the lining of the small intestine)
• reduce the risk of duodenal ulcers returning after healing
• treat sudden benign (noncancerous) gastric ulcers (sores in the lining of the stomach)
• treat gastroesophageal reflux disease (GERD), a severe form of acid reflux
• treat conditions that cause too much stomach acid, such as Zollinger-Ellison syndrome

Cimetidine is usually prescribed as a short-term treatment for ulcers and GERD. For other uses, it may be prescribed as a long-term treatment.

Interactions and warnings for cimetidine

Below, you’ll find information about cimetidine’s possible interactions and warnings.

Interactions of cimetidine

Certain things may affect how a drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take cimetidine, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription or over-the-counter drugs
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for cimetidine” section below.

Warnings for cimetidine

Cimetidine could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether cimetidine is a safe option for you.

Ask your doctor about specific warnings for cimetidine, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Cimetidine can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to cimetidine or any of its ingredients, your doctor will likely recommend that you do not take cimetidine. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to cimetidine, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of cimetidine

If you take cimetidine by mouth, you should not take more cimetidine than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve taken too much cimetidine, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and cimetidine

Information about cimetidine and pregnancy and breastfeeding is described below.

Cimetidine and pregnancy

It’s not known whether cimetidine should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.

Cimetidine and breastfeeding

Cimetidine should not be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication. Your doctor may recommend other ways to feed your child during treatment with cimetidine.

What to ask your doctor

Let your doctor know if you have questions about cimetidine or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• What are my options if I can’t afford my medication?
• Are there any alternative medications that I can take for my condition?
• What happens if I miss a dose of cimetidine?

Resources

• Cimetidine hydrochloride oral solution. (2022). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/f2ec923a-2b88-43c0-ac2a-7ae20c053039/spl-doc
• Cimetidine- cimetidine tablet, film coated. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/28fa98b3-6c78-4b7b-9a37-84c879dbf58a/spl-doc
• Food and Drug Administration. (2020). FDA requests removal of all ranitidine products (Zantac) from the market [Press release]. https://www.fda.gov/news-events/press-announcements/fda-requests-removal-all-ranitidine-products-zantac-market
• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.