Imodium: How It Works, Dosage, Side Effects, Interactions - Healthline

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Imodium Usage, Dosage, and Side Effects

Medically reviewed by Jennie Olopaade, PharmD, RPH — Written by University of Illinois and Carly Vandergriendt — Updated on April 17, 2023

How it works
Dosage
What to avoid
Side effects
Drug interactions
Warnings
Pregnancy & breastfeeding
Summary

Imodium is an over-the-counter (OTC) medication that’s used to relieve diarrhea. It may cause mild side effects in some people.

You can take Imodium as soon as you experience symptoms.

The active ingredient in Imodium is loperamide. It works by making the muscles in your intestines contract more slowly, resulting in firmer stools.

If you follow the package instructions, Imodium poses a low risk of side effects. When side effects do occur, they tend to be mild.

Keep reading to learn what to expect when taking Imodium and how to take it safely.

How does Imodium work?

The muscles in your gastrointestinal tract contract and release at regular intervals. This helps move the food you eat through your digestive system. During this process, the intestines absorb water and nutrients.

With diarrhea, the gut muscles contract too quickly. Food matter moves through your system too fast, resulting in watery bowel movements that are more frequent than usual.

Having diarrhea makes it harder for your intestines to absorb fluids and nutrients such as electrolytes. Your body needs electrolytes to function well. If diarrhea persists, low levels of fluids and electrolytes can trigger dehydration.

Imodium contains loperamide, a drug that slows down muscle contractions in the gut. This in turn slows the movement of food through your digestive tract so the bowel can absorb the fluids and nutrients your body needs, including electrolytes.

After you start taking Imodium, your bowel movements should be smaller, more solid, and less frequent.

Imodium dosage for adults and children

Imodium is available as a caplet, soft gel, and liquid. All three types of Imodium are taken by mouth.

You shouldn’t use Imodium for more than 2 days in a row.

A prescription-strength Imodium caplet is available for long-term use. It’s usually prescribed to treat diarrhea caused by a chronic condition, such as inflammatory bowel disease.

The recommended dosage for Imodium is based on age or weight.

Adults and children 12 years or older

The recommended dosage is 4 milligrams (mg) to start.
This is followed by 2 mg for each loose stool that occurs after that.
Don’t take more than 8 mg per day.

Children younger than 12 years

Dosage should be based on weight. If the child’s weight isn’t known, dosage should be based on age:

Children 60 to 95 pounds (ages 9 to 11 years): 2 mg to start, then 1 mg after each loose stool that occurs after that. Don’t take more than 6 mg per day.
Children 48 to 59 pounds (ages 6 to 8 years): 2 mg to start, then 1 mg after each loose stool that occurs after that. Don’t take more than 4 mg per day.
Children 29 to 47 pounds (ages 2 to 5 years): Use Imodium only on the advice of a pediatrician.
Children under 2 years: Do not give Imodium to children younger than 2 years of age.

What to avoid while taking Imodium

Some people experience drowsiness after taking Imodium. If you’re taking Imodium for the first time, avoid potentially risky activities, such as driving, until you know how your body will react.

It’s also advisable to avoid alcohol when taking Imodium. Drinking alcohol may increase the risk of some side effects, such as dizziness and fatigue.

Finally, keep in mind that certain food and drinks may exacerbate diarrhea and related symptoms. Try to avoid caffeine and dairy, along with foods that are spicy, fatty, fried, or high in fiber until your bowel movements have returned to normal.

Does Imodium have side effects?

Imodium is generally well tolerated by many people. However, it can sometimes cause side effects.

Common side effects

Some of the more common side effects of Imodium can include:

constipation
dizziness
tiredness
headache
nausea
vomiting
dry mouth

Serious side effects

Serious side effects of Imodium are rare. Seek medical assistance right away if you have any of the following symptoms:

bloody or worsening diarrhea
severe dizziness
fainting
signs of a severe allergic reaction, including:
- severe skin rash
- difficulty breathing
- wheezing
- tightness in your throat or chest
- face, lips, mouth, or tongue swelling
swelling or pain in the abdomen
painful, peeling, or blistering skin

Drug interactions

Imodium interacts with certain drugs that break down in your body in the same way that Imodium does. These interactions can potentially lead to increased levels of either medication in your body.

Some examples of medications that can interact with Imodium include:

atropine
alosetron
diphenhydramine
erythromycin
fenofibric acid
metoclopramide
narcotic pain medications such as morphine, oxycodone, and fentanyl
quinidine
the HIV drugs saquinavir and ritonavir
pramlintide

Imodium also interacts with other antidiarrheal drugs or medications that cause constipation.

Contraindications and warnings

Imodium is a safe medication for most people. However, it should still be used carefully. And in some cases, it should be avoided. The following warnings can help keep you safe.

Conditions of concern

Talk with your doctor before taking Imodium if you have any of the following conditions:

liver problems
HIV with infectious colitis
ulcerative colitis
an intestinal bacterial infection
allergy to Imodium

Other warnings

Do not take more than the maximum daily dosage of Imodium. Also, do not take it for longer than 2 days unless directed by a doctor to do so.

You should see an improvement in your symptoms within 2 days. If you don’t, call a doctor. Your diarrhea may be caused by bacteria, a virus, or another cause. This may require treatment with a different medication.

Don’t take Imodium if you have blood in your stools or black stools. These symptoms may be a sign of some other problem in your digestive tract. Make an appointment with a doctor if you have bloody or black stools.

Never take Imodium if you have abdominal pain without diarrhea. Imodium isn’t approved for use in this situation. Depending on the cause of your pain, taking Imodium could make the pain worse.

In case of overdose

To avoid overdose, be sure to carefully follow the dosage instructions on your Imodium package. Symptoms of an overdose of Imodium can include:

nausea
vomiting
severe drowsiness
pain in your abdomen
severe constipation

If you or someone you know accidentally takes too much Imodium, call the poison control hotline at 800-222-1222 for assistance.

Pregnancy and breastfeeding

Not enough research has been done to know whether Imodium is safe to use during pregnancy. If you are pregnant, talk with your doctor before taking Imodium. Ask if this medication is safe for you to use during pregnancy.

If you’re breastfeeding, also ask your doctor whether Imodium is safe for you. It’s known that small amounts of Imodium may pass into breast milk, but it’s not likely to harm a child who is breastfed. However, you should still consult your doctor before using Imodium.

Learn more: Pregnancy and diarrhea: Causes and remedies »

The bottom line

Imodium is an OTC drug for people with acute diarrhea. It contains loperamide, which works by decreasing muscle contractions in your gastrointestinal tract.

Imodium can cause side effects, but most of the time these are mild. To reduce your risk of adverse effects when taking Imodium, always carefully follow the instructions on the label.

If you have questions about Imodium, talk with your doctor or pharmacist. Seek medical attention if your symptoms worsen or your diarrhea lasts longer than 2 days.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Akel T, et al. (2018). Loperamide cardiotoxicity: A brief review.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6931594/
Definition & facts for diarrhea. (2016).https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/definition-facts
Imodium A-D – loperamide hydrochloride tablet, film coated. (2021).https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=01da76d0-1979-4c45-9d39-c72ae4e4ffe2
Imodium A-D. (2018).https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/019860Orig1s033lbl.pdf
Loperamide. (2021).https://www.nhs.uk/medicines/loperamide/
Loperamide. (2022).https://pubchem.ncbi.nlm.nih.gov/compound/Loperamide
Sahi N, et al. (2021). Loperamide.https://www.ncbi.nlm.nih.gov/books/NBK557885/
Schifano F, et al. (2018). Is there such a thing as a ‘lope’ dope? Analysis of loperamide-related European Medicines Agency (EMA) pharmacovigilance data reports.https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204443

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Medically reviewed by Jennie Olopaade, PharmD, RPH — Written by University of Illinois and Carly Vandergriendt — Updated on April 17, 2023

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