Imodium (loperamide) is an over-the-counter drug that’s used to treat symptoms of diarrhea. As with other drugs, Imodium can cause side effects, such as constipation, drowsiness, and dizziness.

Imodium can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Imodium in clinical trials:

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.

Mild side effects can occur with Imodium use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to the prescribing information for Imodium A-D oral solution, Imodium A-D oral capsule, or Imodium A-D oral tablet.

Mild side effects that have been reported with Imodium include:

  • constipation
  • abdominal cramps or pain
  • drowsiness
  • dizziness
  • nausea
  • dry mouth
  • gas
  • headache
  • indigestion
  • vomiting

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Imodium and want to tell the FDA about it, visit MedWatch.

Imodium may cause serious side effects. Most are rare, but some may be more common. The list below may not include all possible serious side effects of the drug. For more information, you can refer to the prescribing information for Imodium A-D solution, Imodium A-D capsule, or Imodium A-D tablet.

If you develop serious side effects while taking Imodium, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • toxic megacolon (severe inflammation of the large intestine), which may include symptoms such as:
    • bloated abdomen
    • bloody diarrhea
    • nausea and vomiting
    • painful bowel movements
    • fast heart rate
  • necrotizing enterocolitis (serious intestinal problem that mainly affects premature babies), which may include symptoms such as:
    • problems digesting food
    • bloody stool
    • low heart rate
    • swollen or bloated abdomen
  • fainting
  • serious skin conditions, such as Stevens-Johnson syndrome or toxic epidermal necrolysis
  • paralytic ileus (temporary stoppage in movement in your intestines)*
  • serious heart problems*

* For more information about this side effect, see “Side effect specifics” below.

ALLERGIC REACTION

For some people, Imodium can cause an allergic reaction.

But it’s not clear whether this side effect occurred in studies of Imodium A-D oral solution, Imodium A-D oral capsule, or Imodium A-D oral tablet.

In general, symptoms of allergic reaction can be mild or serious. You can learn more about possible symptoms in this article.

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 Imodium, your doctor may recommend taking a different medication instead.

Imodium may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Does Imodium cause long-term side effects?

Long-term side effects aren’t expected with Imodium. 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.

This information comes from studies of Imodium A-D oral solution, Imodium A-D oral capsule, and Imodium A-D oral tablet.

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

How do side effects of Imodium seen in older adults compare with those seen in younger adults?

It’s not likely. In studies, side effects were similar in older adults (ages 65 years and above) and younger adults.

However, older adults (ages 65 years and above) may have a higher risk of heart problems, such as QT prolongation, and paralytic ileus (temporary stoppage in movement in your intestines)*. Imodium can cause QT prolongation and paralytic ileus as side effects. So, older adults may be at higher risk of these effects if they take Imodium.

If you have concerns about taking Imodium given your age, talk with your doctor.

* For more information about this side effect, see “Side effect specifics” below.

Can Imodium cause changes in blood pressure?

It’s not likely. Changes in blood pressure weren’t reported in studies of Imodium A-D oral solution, Imodium A-D oral capsule, or Imodium A-D oral tablet.

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

Is misuse possible with Imodium?

Not usually. When taking the recommended dosages of Imodium, the drug does not cross the blood-brain barrier or produce an opioid effect. (Imodium is a mu opioid agonist.)

However, if the drug is taken in extremely high doses, Imodium can enter the central nervous system and cause euphoria. Imodium can sometimes be misused for this effect. Misuse of Imodium can lead to serious effects such as prolonged QT interval, Torsades de Pointes, and respiratory depression. It can also lead to dependence on the drug and withdrawal symptoms after stopping the drug.

If you have questions about Imodium and misuse, talk with your doctor or pharmacist.

Learn more about some of the side effects that Imodium may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Imodium A-D oral solution, Imodium A-D oral capsule, and Imodium A-D oral tablet.

Paralytic ileus

Taking Imodium can increase your risk of paralytic ileus. This was one of the more common side effects of Imodium.

Paralytic ileus is a temporary stoppage in movement in your intestines. It can lead to symptoms such as:

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

What you can do

If you experience symptoms of paralytic ileus, stop taking Imodium and call your doctor right away. If your symptoms feel life threatening or you’re having a medical emergency, call 911 or your local emergency number for medical help right away. Your doctor can prescribe treatment and determine if it’s safe for you to continue taking Imodium.

Serious heart problems

In rare cases, Imodium can cause serious heart problems, which can lead to death. This risk is higher if you take higher doses of Imodium than recommended.

Heart problems can include long QT syndrome, ventricular tachycardia, and irregular heart rhythms. Symptoms of these conditions can include:

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

What you can do

In some cases, these heart problems can be life threatening and lead to death. For this reason, doctors may not recommend Imodium if you have a history of heart problems. Tell your doctor about any heart conditions you have before you take Imodium. Also, take Imodium exactly as recommended. And do not take it for longer than 2 days unless directed by your doctor.

If you experience any symptoms of heart problems, call your doctor right away. If your symptoms are severe or feel life threatening, call 911 or your local emergency number.

Below is important information you should consider before taking Imodium.

Other precautions

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:

Disclaimer: Medical News Today 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.