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Overview: Loperamide is commonly used to treat diarrhea, including traveler’s diarrhea. Common side effects can include constipation, drowsiness, dizziness, nausea, and stomach cramps. Do not drive or operate heavy machinery until you know how loperamide affects you. Loperamide is available as an over-the-counter and prescription medicine.

Uses

What is loperamide used for?

Loperamide is commonly used to treat diarrhea, including short-term, long-term (chronic), and traveler’s diarrhea. Loperamide can also be used to help reduce the amount of poop after an ileostomy, a type of surgery that changes how poop exits your body. 

These uses may vary depending on whether you are taking prescription or over-the-counter (OTC) loperamide. Loperamide may also be used for other conditions as determined by your health care provider.

How does loperamide work (mechanism of action)?

Loperamide works to help slow down the movement of your gut. It also affects the movement of water and electrolytes in your gut, which can help move water out of your poop and make it more solid. 

How is loperamide supplied (dosage forms)?

Brands and other names

  • Imodium A-D

Example dosage forms and strengths

  • 2 mg oral capsules
  • 1 mg/7.5 mL oral solution or oral suspension
  • 2 mg oral tablets

How should I store loperamide?

Loperamide should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of loperamide?

The most common side effects of loperamide are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Constipation
  • Dizziness
  • Nausea
  • Stomach cramps
  • Drowsiness or tiredness

There may be other side effects of loperamide that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of loperamide?

While less common, the most serious side effects of loperamide are described below, along with what to do if they happen.

Severe Allergic Reactions. Loperamide may cause allergic reactions, which can be serious. Stop taking loperamide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Heart Rhythm Changes. Loperamide may cause a rare, dangerous heart rhythm problem called QT prolongation and torsade de pointes if you take more than directed. Some people have a higher risk of this, including people who are older, have other people in their family who have had these conditions, have low potassium or magnesium levels, or who take medicines that can prolong the QT interval. Tell your health care provider right away if you faint or have changes in your heart rate or rhythm, such as a fast or skipping heartbeat.

Stomach Problems. Stop taking loperamide and call your health care provider right away if you have any of the following symptoms that could be signs of a serious condition.

  • Swelling or bulging in your stomach area
  • Severe constipation 
  • Fever
  • Blood in your poop or black poop

Warnings & Precautions

Who should not use loperamide?

Allergies to Ingredients. People who are allergic to any of the following should not take loperamide.

  • Imodium
  • Imodium A-D
  • Loperamide
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific loperamide products they stock.

Children Under Age 2. Loperamide should not be taken by children under 2 years old due to the risk of serious breathing and heart problems. In addition, some over-the-counter (OTC) loperamide products should not be taken by certain children older than age 2. Read the label closely and ask your pharmacist or another health care provider if you are not sure whether the product is safe for children. 

Certain Stomach Problems. Loperamide should not be taken if you have any of the following. 

What should I know about loperamide before using it?

If loperamide was prescribed to you by a health care provider, take it as prescribed. If you are taking over-the-counter (OTC) loperamide, follow the instructions that come with the product.

Do not share loperamide that was prescribed to you by a health care provider with other people, even if they have the same condition as you. It may harm them.

Keep loperamide out of the reach of children.

Loperamide can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how loperamide affects you.

If you are taking loperamide liquid, use the dosing cup that comes with your medicine to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Loperamide liquid should be shaken well before taking each dose. Ask your pharmacist if you do not have a dosing cup or if you have any questions about how to take the medicine properly. 

If you are taking loperamide over-the-counter or for short-term diarrhea, tell your health care provider if it has been more than two days and your diarrhea has not gotten better or has gotten worse. 

Drink plenty of water or other clear liquids to help prevent dehydration that may be caused by diarrhea.

Children or older adults can be at a greater risk of some side effects from loperamide. Talk to your health care provider about your risks if you are in one of these age groups.

What should I tell my health care provider before using loperamide?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if loperamide is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have or have had any of the following.

  • Fever
  • Mucus in your poop
  • Stomach problems other than the condition being treated
  • Liver problems
  • Heart problems, including an abnormal heart rhythm
  • AIDS

Other Medicines and Supplements. Loperamide may interact with other medicines and supplements. Before taking loperamide, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how loperamide could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. Loperamide may pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take loperamide while breastfeeding.

Interactions

Does loperamide interact with foods or drinks?

There are no known interactions between loperamide and foods or drinks.

It is unknown if drinking alcohol will affect loperamide. The risk of tiredness, dizziness, or drowsiness may increase if you drink alcohol while taking loperamide.

Does loperamide interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking loperamide.

  • Fluconazole (Diflucan), itraconazole (Sporanox, Tolsura), ketoconazole, posaconazole (Noxafil), or voriconazole (Vfend), which are medicines used for fungal infections
  • Gemfibrozil (Lopid), which is a medicine for high cholesterol
  • Quinidine, which is a medicine used to treat malaria or control your heart rate or rhythm 
  • Ritonavir (Norvir), which is a medicine commonly used to treat HIV
  • Any medicine that can cause QT prolongation, which is a potentially dangerous heart rhythm problem, such as amiodarone, chlorpromazine, methadone, moxifloxacin, or ziprasidone

Some other medicines may alter the blood levels of loperamide. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with loperamide. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much loperamide?

If you or someone else has used too much loperamide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of loperamide?

If you miss a dose of loperamide and you are taking it on a regular basis, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses. 

If you are taking loperamide only when needed, take it as your health care provider recommends. Do not take double or extra doses. Ask your health care provider what to do if you are not sure.