Cimetidine oral tablet side effects: A detailed guide

Specifically, the Food and Drug Administration (FDA) has approved cimetidine oral tablet for adults and children ages 16 and older for:

• short-term treatment of ulcers in the stomach or upper part of the small intestine
• reducing the risk of another ulcer in the upper part of the small intestine
• treating erosive esophagitis due to gastroesophageal reflux disease (GERD)
• treating certain conditions related to too much stomach acid, such as Zollinger-Ellison syndrome

This article describes possible side effects of cimetidine oral tablet. You can explore this overview article to learn more about cimetidine, including the drug’s uses, side effects, ways to save on cost, and more.

Cimetidine oral tablet is a generic version of the brand-name drug Tagamet. But prescription Tagamet is no longer available. Over-the-counter (OTC) Tagamet is still available. To learn more about this form, talk with your doctor.

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More common side effects of cimetidine

Cimetidine oral tablet may cause mild or serious side effects. Below are some of the more common side effects of this medication.

Commonly reported side effects of cimetidine oral tablet include:

• headache*
• diarrhea
• dizziness
• sleepiness
• breast tissue growth in males*†

* To learn more about this side effect, see the “Side effects of cimetidine in detail” section below.
† Sex and gender exist on spectrums. In this article, we use the term “males” to refer to a person’s sex assigned at birth.

Mild side effects of cimetidine

Cimetidine may cause certain mild side effects. Typically, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.

Mild side effects of cimetidine oral tablet that occurred in studies include:

• headache*
• diarrhea
• dizziness
• sleepiness
• breast tissue growth in males*†
• muscle or joint pain
• hair loss
• mild allergic reaction*

* To learn more about this side effect, see the “Side effects of cimetidine in detail” section below.
† Sex and gender exist on spectrums. In this article, we use the term “males” to refer to a person’s sex assigned at birth.

Cimetidine oral tablet may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.

Serious side effects of cimetidine

Cimetidine may cause certain serious side effects. If you have any serious side effects from cimetidine oral tablet, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.

After the FDA approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with cimetidine.

Serious side effects of cimetidine oral tablet that occurred in studies include:

• confusion*
• agitation
• psychosis
• depression or anxiety
• hallucinations
• liver problems, including high liver enzyme levels
• inflammation of the pancreas (pancreatitis)
• kidney problems and urinary retention
• heart problems, including fast or slow heart rate
• low level of white blood cells
• low level of platelets (a type of blood cell that helps form clots)
• certain types of anemia
• severe skin reactions, such as Stevens-Johnson syndrome
• severe allergic reaction*

* To learn more about this side effect, see the “Side effects of cimetidine in detail” section below.

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Common questions about side effects of cimetidine

Here are answers to some common questions about side effects of cimetidine oral tablet. If you have other questions, talk with your doctor or pharmacist.

Is cimetidine safe for older adults?

Not necessarily. In some cases, cimetidine oral tablet has led to side effects such as confusion, agitation, psychosis, or hallucinations. These side effects were reported mostly in people who had liver or kidney problems due to an existing illness. But older adults, such as people ages 50 years or older, may also be at an increased risk of these side effects.

Older adults are more likely to have kidney disease. And people with kidney problems may need a lower dose of cimetidine. That’s because the levels of cimetidine oral tablet may build up in people with kidney problems.

Cimetidine also interacts with many other medications. Older adults are more likely to take other medications, so this could also be a concern with cimetidine oral tablet.

Talk with your doctor or pharmacist to learn more about how your age could affect your risk of side effects with cimetidine oral tablet.

How do side effects of cimetidine seen in males compare with those seen in females?

Overall, studies of cimetidine oral tablet did not report different side effects in females compared to males.*

But breast tissue growth in males*† has been reported with the use of cimetidine oral tablet. This was seen in people taking the drug for one month or longer. It occurred more often in people taking cimetidine oral tablet to treat conditions related to too much stomach acid, such as Zollinger-Ellison syndrome.

Erectile dysfunction has also been reported in people taking cimetidine oral tablet. This side effect was seen in people taking the drug to treat conditions related to too much stomach acid, usually at high doses, for at least 12 months.

If you’d like to know more about the possible side effects of cimetidine oral tablet, talk with your doctor or pharmacist.

* Sex and gender exist on spectrums. In this article, we use the terms “male” and “female” to refer to a person’s sex assigned at birth.
† To learn more about this side effect, see the “Side effects of cimetidine in detail” section below.

Does cimetidine cause long-term side effects?

Long-term side effects aren’t expected with cimetidine oral tablet. In studies, specific side effects weren’t seen in people who had taken the drug for a long time. Long lasting side effects after treatment ended also weren’t reported. Most side effects went away after the drug was stopped.

That said, some serious side effects*, if they occur, could affect your health long term. For example, in very rare cases, liver injury and death have been reported with cimetidine oral tablet. Cimetidine oral tablet is in a group of drugs known as H2 blockers. This side effect has also been reported with other H2 blockers.

Talk with your doctor if you have more questions about possible long-term side effects with cimetidine.

* For more information about the serious side effects of cimetidine oral tablet, see the “Serious side effects of cimetidine” section above.

Side effects of cimetidine in detail

Below you’ll find details on some of the side effects of cimetidine oral tablet.

Headache

In studies, headache was common in people taking cimetidine oral tablet. This side effect is usually mild, but in some people, it could be severe.

Higher doses of cimetidine oral tablet may increase the risk of headache.

Ways to manage

Most mild headaches shouldn’t last long. If you have a sudden, severe headache, or you have other symptoms, such as trouble speaking or confusion, get medical attention right away. This could be a sign of a stroke.

If you have a bothersome headache while taking cimetidine oral tablet, tell your doctor. Depending on the cause of your headache, your doctor may recommend a pain reliever to manage your symptoms. But some pain relievers may need to be avoided in people taking cimetidine oral tablet.

If you’re concerned about headache with cimetidine oral tablet, tell your doctor. They can discuss the benefits and risks of this drug and other possible treatments for your condition.

Confusion

In studies, confusion was rare in people taking cimetidine oral tablet. This side effect is usually mild, but in some cases, it could be severe.

With confusion, you feel like you can’t think clearly. You may also have a hard time focusing or making decisions.

Certain factors can increase the risk of confusion with cimetidine oral tablet. It’s been reported mostly in people who had liver or kidney problems due to an existing illness. But older adults, such as people ages 50 years or older, may also be at an increased risk of these side effects.

This side effect usually happened within 2–3 days of starting treatment with cimetidine oral tablet. It usually ended within 3–4 days after stopping the drug.

Ways to manage

If you experience symptoms of confusion, tell your doctor. Your doctor will try to find out what the possible cause of confusion is.

If your doctor thinks that confusion is due to cimetidine oral tablet, they’ll likely recommend stopping it and using a different medication.

Breast tissue growth in males*

In studies, breast tissue growth in males* was common in people taking cimetidine oral tablet. It’s usually mild, but some people may find it bothersome.

Symptoms may include breast tenderness, swelling, or discharge.

Certain factors can increase the risk of breast tissue growth in males with cimetidine oral tablet. It was seen in people taking the drug for one month or longer. It also occurred more often in people taking cimetidine oral tablet to treat certain conditions related to too much stomach acid, such as Zollinger-Ellison syndrome.

* Sex and gender exist on spectrums. In this article, we use the term “male” to refer to a person’s sex assigned at birth.

Ways to manage

If you have concerns about breast tissue growth, tell your doctor. They’ll likely discuss whether other treatment options may be a better choice for your condition.

If you experience breast tissue growth while taking cimetidine oral tablet, your doctor will likely recommend that you stop the drug and switch to another medication, if needed.

Allergic reaction

For some people, cimetidine oral tablet can cause an allergic reaction.

Symptoms can be mild or serious, and they may include:

• itchiness
• skin rash
• swelling under the skin, usually affecting eyelids, lips, hands, or feet
• swelling of the mouth, tongue, or throat, which can make it hard to breathe
• flushing (temporary warmth, redness, or deepening of skin color)

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to cimetidine oral tablet, your doctor may recommend taking a different medication instead.

Warnings for cimetidine

Below are some factors you may want to discuss with your doctor before taking cimetidine oral tablet.

Warnings

It may not be safe for you to take cimetidine oral tablet if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether cimetidine oral tablet is a safe treatment option for you.

Before taking cimetidine oral tablet, tell your doctor about your health and medications you take. Things to consider include:

• confusion
• agitation
• psychosis
• depression or anxiety
• hallucinations
• liver or kidney problems
• interactions with other medications, such as warfarin, phenytoin, and propranolol
• a weak immune system
• pregnancy or breastfeeding
• past allergic reaction to cimetidine

Cimetidine and pregnancy

It’s not known whether cimetidine oral tablet 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 oral tablet should usually not be taken while breastfeeding. Cimetidine passes into breast milk.

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.

Cimetidine and alcohol

Cimetidine oral tablet isn’t known to interact with alcohol.

But alcohol may cause certain side effects that can also happen with cimetidine oral tablet. These include headache, dizziness, or diarrhea. Drinking alcohol while taking cimetidine oral tablet may make these side effects worse.

Heavy drinking can also lead to ulcers. And cimetidine oral tablet may be prescribed to treat ulcers.

If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with cimetidine oral tablet.

What to ask your doctor

This article describes common and serious side effects of cimetidine oral tablet. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.

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

• How does the risk of side effects with cimetidine compare to famotidine or omeprazole?
• Do I have a higher risk of side effects with cimetidine oral tablet than other people?
• Does cimetidine oral tablet interact with other medications I take?
• Is it safe to take an OTC medication for my condition instead of cimetidine oral tablet?

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.