Loperamide

This form:

Warning

Improper use of this medication (overuse or abuse) may cause serious harm, such as fast/irregular heartbeat or death. Do not increase your dose, take it more often, or take it for longer than directed. Taking loperamide with certain other medications may also cause harm. See also Precautions, Drug Interactions, and Overdose sections.

This medication should not be used by children younger than 2 years due to an increased risk of side effects (such as slow/shallow breathing, fast/irregular heartbeat).

Precautions

Before taking loperamide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

If you have any of the following health problems, consult your doctor or pharmacist before using this medication: stomach/abdominal pain without diarrhea, bowel obstruction (such as ileus, megacolon, abdominal distention), black/tarry stool, blood/mucus in your stool, high fever, HIV infection/AIDS, liver problems, certain stomach/intestinal infections (such as Salmonella, Shigella), certain type of bowel disease (acute ulcerative colitis).

The rapidly dissolving tablets may contain aspartame or phenylalanine. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame or phenylalanine, consult your doctor or pharmacist regarding the safe use of this medicine.

Antibiotics may rarely cause a severe intestinal condition due to a bacteria called C. difficile. Symptoms include: diarrhea that doesn't stop, abdominal or stomach pain/cramping, or blood/mucus in your stool. This condition may occur during treatment or weeks to months after treatment has stopped. This medication may make this condition worse. Do not use this anti-diarrhea product, especially after recent antibiotic use, if you have the above symptoms without talking with your doctor first.

Loperamide may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using loperamide, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using loperamide safely.

This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

Children may be more sensitive to the side effects of this drug, especially drowsiness. Children are also at a higher risk for dehydration. See also Warning and How to Use sections.

During pregnancy, this medication should be used only if clearly needed. Discuss the risks and benefits with your doctor.

This drug passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.

Side Effects

Dizziness, drowsiness, tiredness, or constipation may occur. If any of these effects last or get worse, tell your doctor promptly.

If your doctor has prescribed this medication, remember that your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Stop taking this medication and get medical help right away if you have any very serious side effects, including: severe constipation/nausea/vomiting, stomach/abdominal pain, uncomfortable fullness of the stomach/abdomen, fast/irregular heartbeat, severe dizziness, fainting.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Copyright © 2025 TraceGains, Inc. All rights reserved.

RxAnswers™ is a copyrighted combined product from TraceGains and First DataBank, Inc.

Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.

Learn more about First DataBank

There are some limitations on the information provided in “Nutrient Interactions.” Do NOT rely solely on the information in this article. Please read the disclaimer.

Learn more about TraceGains, the company.

TraceGains and/or its suppliers make no warranties or representations as to the accuracy or completeness of this content herein or that of any organization referred or linked to within this content and will not be liable for any damages arising out of your access to or use of any information found herein or that of any organization referred to within this content.

Information expires December 2025.