Reviewed on 12/17/2021

Brand Name: Imodium, K-Pek II, NeoDiaral, Diaraid

Generic Name: Loperamide

Drug Class: Antidiarrheals

What Is Loperamide and How Does It Work?

Loperamide is a prescription medication used to treat acute diarrhea, chronic diarrhea, and traveler’s diarrhea. 

  • Loperamide is available under the following different brand names: Imodium, K-Pek II, NeoDiaral, Diaraid

What Are Dosages of Loperamide?

Adult and pediatric dosage


  • 1mg/5mL
  • 1mg/7.5mL


  • 1mg/7.5mL


  • 2mg


  • 2mg

Tablet Chewable

  • 2mg

Acute Diarrhea

Adult dosage

  • 4 mg initially, then 2 mg after each loose stool; not to exceed 16 mg/day (8mg/day for self-medication); discontinue if no improvement seen within 48 hours

Pediatric dosage

First day of treatment:

  • 2-6 years (13-20 kg): 1 mg every 8 hours orally
  • 6-8 years (20-30 kg): 2 mg every 12 hours orally
  • 8-12 years (weighing over 30 kg): 2 mg every 8 hours orally

Second & Subsequent Doses

  • 0.1 mg/kg orally after each loose stool; not to exceed the dose recommended for first 24 hours

Chronic Diarrhea

Adult dosage

  • 4 mg initially, then 2 mg after each loose stool until controlled, and then 4-8 mg/day in divided doses

Pediatric dosage

  • 0.08-0.24 mg/kg/day orally divided every 12 hours

Traveler’s Diarrhea

Adult dosage

  • 4 mg after first loose stool, then 2 mg after each subsequent stool; not to exceed 8 mg/day

Pediatric dosage

  • Children younger than 6 years of age: Safety and efficacy not established
  • Children 6-8 years: 2 mg after first loose stool, then 1 mg after each subsequent stool; not to exceed 4 mg/day
  • Children 8-12 years: 2 mg after first loose stool, then 1 mg after each subsequent stool; not to exceed 6 mg/day
  • Children 12 years or older: 4 mg after first loose stool, then 2 mg after each subsequent stool; not to exceed 8 mg/day

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”.

What Are Side Effects Associated with Using Loperamide?

Common side effects of Loperamide include:

  • constipation, 
  • dizziness, 
  • drowsiness,
  • tiredness
  • skin rash,
  • itching,
  • nausea, and 
  • stomach cramps

Serious side effects of Loperamide include:

  • hives, 
  • difficulty breathing, 
  • swelling in the face or throat, 
  • fever, 
  • sore throat
  • burning in eyes, 
  • skin pain, 
  • red or purple skin rash that spreads and causes blistering and peeling, 
  • diarrhea that is watery or bloody, 
  • stomach pain, 
  • bloating, 
  • ongoing or worsening diarrhea, 
  • fast or pounding heartbeats, 
  • fluttering in the chest, 
  • shortness of breath, and
  • sudden dizziness

Rare side effects of Loperamide include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Loperamide?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Loperamide has severe interactions with no other drugs.
  • Loperamide has serious interactions with at least 23 other drugs. 
  • Loperamide has moderate interactions with at least 66 other drugs.
  • Loperamide has minor interactions with the following drugs:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this drug, tell your doctor or pharmacist of all the drugs you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warning And Precautions For Loperamide?


  • Hypersensitivity, bloody diarrhea, high fever, infectious diarrhea, and pseudomembranous colitis
  • Patients in whom constipation must be avoided
  • Abdominal pain without diarrhea
  • Avoid use as primary therapy with acute dysentery (bloody stools and high fever, acute ulcerative colitis, bacterial enterocolitis [caused by Salmonella, Shigella, and Campylobacter), pseudomembranous colitis associated with antibiotic use)
  • Children younger than 2 years

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Loperamide?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Loperamide?”


  • May cause drowsiness or dizziness, which may impair physical abilities to operate heavy machinery or tasks requiring mental alertness
  • Hypersensitivity reactions reported, including anaphylaxis, rash, urticaria, and rare cases of Steven’s Johnson syndrome or toxic epidermal necrolysis
  • Discontinue if no improvement is seen within 48 hours in patients with acute diarrhea, symptoms worsen, or abdominal swelling or bulging develops
  • Discontinue promptly if constipation, abdominal pain or distention, blood in stool, or ileus develops; do not use when peristalsis inhibition should be avoided (ie, due to potential for ileus, megacolon, or toxic megacolon)
  • Discontinue therapy if symptoms of abdominal distention occur in patients with AIDS; cases of toxic megacolon reported with infectious colitis, resulting from viral or bacterial pathogens
  • Use with caution in patients with hepatic impairment due to reduced first-pass metabolism; monitor for signs of CNS toxicity
  • Use of higher than recommended doses or abuse of loperamide can result in serious cardiac adverse events, including QT interval prolongation, Torsades de Pointes, or other ventricular arrhythmias, syncope, and cardiac arrest; in cases of abuse, individuals often use other drugs together with loperamide in attempts to increase its absorption and penetration across the blood-brain barrier, inhibit loperamide metabolism, and enhance its euphoric effects
  • Dehydration, particularly in pediatric patients less than 6 years of age, may further influence the variability of response to loperamide
  • Avoid loperamide in combination with drugs or herbal products known to prolong QT interval, including Class 1A (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmics, antipsychotics (e.g., chlorpromazine, haloperidol, thioridazine, ziprasidone), antibiotics (e.g., moxifloxacin), or any other drug known to prolong the QT interval (e.g., pentamidine, methadone)
  • Avoid administering therapy to patients with risk factors for QT prolongation, including patients with congenital long QT syndrome, with a history of cardiac arrhythmias or other cardiac conditions, elderly patients, and those with electrolyte abnormalities
  • Patients with a history of abnormal heart rhythm or liver disease should ask their healthcare provider before using the product; taking more than directed can cause serious heart problems or death
  • The potential toxic dose in patients younger than 6 years: 0.4 mg/kg

Pregnancy and Lactation

  • Use in pregnancy may be acceptable. 
  • Lactation: Not known if distributed in breast milk; use caution.
Medscape. Loperamide.

https://reference.medscape.com/drug/imodium-k- pek-ii-loperamide-342041

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