Key takeaways

  • Imodium typically causes mild, temporary reactions like constipation, dizziness, and stomach discomfort that usually resolve within a few weeks of use.
  • Taking doses higher than recommended can lead to dangerous heart rhythm problems, including irregular heartbeat, fainting, and potentially life-threatening cardiac complications.
  • Individuals with existing heart conditions, liver disease, or inflammatory bowel conditions should consult a healthcare professional before using this medication due to increased risk of serious complications.

Imodium (loperamide) is an over-the-counter drug used to treat diarrhea symptoms. As with other drugs, Imodium can cause side effects.

Mild side effects can occur with Imodium use, and some are more common than others. These side effects may be temporary, lasting a few days to weeks. They include:

  • dry mouth
  • gas and indigestion
  • abdominal cramps or pain
  • nausea
  • constipation
  • urinary retention
  • drowsiness and dizziness

If the side effects last longer than a few weeks, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These side effects were reported in clinical trials of Imodium A-D oral solution, Imodium A-D oral capsule, and Imodium A-D oral tablet.

Experiencing side effects? After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews its side effects. If you develop a side effect while taking this medication and want to report it to the FDA, you can visit MedWatch or call 800-FDA-1088.

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Imodium may cause serious side effects, although most are rare. If you develop symptoms of serious side effects, call your doctor right away or call 911 if the side effects seem life threatening.

Serious side effects include:

Toxic megacolon

Toxic megacolon is severe inflammation of the large intestine. It may cause symptoms such as:

  • bloated abdomen
  • bloody diarrhea
  • nausea and vomiting
  • painful bowel movements
  • fast heart rate

Necrotizing enterocolitis

Necrotizing enterocolitis is a serious intestinal problem that mainly affects premature babies. Symptoms may include:

  • problems digesting food
  • bloody stool
  • low heart rate
  • swollen or bloated abdomen

Serious skin conditions

This includes conditions such as Stevens-Johnson syndrome or toxic epidermal necrolysis.

Paralytic ileus

Taking Imodium can increase your risk of paralytic ileus, which is a temporary stoppage in movement in your intestines. Symptoms may include:

  • bloated, bulging, or swollen stomach
  • pain
  • cramping
  • nausea
  • constipation
  • difficulty passing gas

If you experience these symptoms, stop taking Imodium and call your doctor right away.

Serious heart problems

In rare cases, Imodium can cause life threatening heart problems, such as long QT syndrome, ventricular tachycardia, and irregular heart rhythms. The risk is higher if you take higher doses of Imodium than recommended.

Symptoms may include:

  • heart palpitations
  • dizziness
  • sudden fainting
  • seizures
  • chest pain
  • shortness of breath
  • lightheadedness
  • sudden weakness

Do not take Imodium for more than 2 days unless your doctor directs you to do so.

Allergic reactions

For some people, Imodium can cause an allergic reaction. For mild symptoms, such as a mild rash, call your doctor right away. For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 immediately because these symptoms can become life threatening.

Long-term side effects aren’t expected with Imodium, and they were not reported in clinical studies.

In studies, side effects were similar in older adults (ages 65 years and older) and younger adults.

However, older adults may have a higher risk of heart problems and paralytic ileus.

It’s not likely, as changes in blood pressure weren’t reported in studies of Imodium.

If you experience blood pressure changes while taking Imodium, talk with your doctor. They can help determine the cause and discuss potential treatment options.

Not usually at the recommended dosages. However, if taken in extremely high doses, Imodium can enter the central nervous system and cause euphoria. Misuse can lead to dependence, withdrawal symptoms, and serious effects such as respiratory depression and heart problems.

Medical Perspective

“Please visit a doctor for diarrhea if you notice significant weight loss, blood in your bowel movement, and if the duration has been longer than a few weeks.”

— Kiran Khanani, PharmD

Read more: Home remedies to manage diarrhea and when to see a doctor

Quotes represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Before taking Imodium, discuss your health history with your doctor. Imodium may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Imodium may cause mild, temporary side effects, such as constipation, dizziness, and abdominal cramps.

Misusing or taking higher than the recommended doses of Imodium can lead to rare but serious complications, including life threatening heart problems.

If you have an underlying health condition, seek advice from a doctor or pharmacist before using Imodium.

Disclaimer: While Medical News Today strives for factual, comprehensive, and current drug information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.