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Loperamide

AEMPS

Antipropulsives

ATC code: A07DA03

Brand names: Imodium

Updated · Methodology

Indications

A

Travelers' diarrhea

First line

In traveler's diarrhea in adults, loperamide cuts symptom duration by about 50%. In mild disease it is appropriate as start-of-illness monotherapy; in moderate-to-severe disease the antibiotic (azithromycin or a fluoroquinolone) is the primary agent and loperamide is added to it. Loperamide must not be taken in dysentery (bloody stool, high fever, or suspected invasive infection): slowing gut motility prolongs the illness and risks toxic megacolon. Not used in children under 12 in this setting.

Sources

  1. Journal of Travel Medicine: Guidelines for the prevention and treatment of travelers’ diarrhea: a graded expert panel report (2017)
  2. Travel Med Infect Dis: Systematic review of loperamide: No proof of antibiotics being superior to loperamide in treatment of mild/moderate travellers' diarrhoea. (2016)
  3. Clin Infect Dis: Trial Evaluating Ambulatory Therapy of Travelers' Diarrhea (TrEAT TD) Study: A Randomized Controlled Trial Comparing 3 Single-Dose Antibiotic Regimens With Loperamide. (2017)
  4. Journal of Travel Medicine: Loperamide Plus Azithromycin More Effectively Treats Travelers’ Diarrhea in Mexico than Azithromycin Alone (2007)
  5. Clinical Gastroenterology and Hepatology: Treatment of Travelers’ Diarrhea: Randomized Trial Comparing Rifaximin, Rifaximin Plus Loperamide, and Loperamide Alone (2007)

ICD-10: A09 · ICD-11: 1A40

B

Acute diarrhea in adults

First line

In acute diarrhea in adults, the first line is oral rehydration (ORS); loperamide is a symptomatic antidiarrheal that slows motility and reduces stool frequency. Guidelines ( 2017) recommend it as an adjunct with a weak, conditional recommendation in non-invasive watery diarrhea in immunocompetent adults, and more firmly as an add-on to an antibiotic in traveler's diarrhea. Loperamide is contraindicated in invasive or inflammatory diarrhea (blood in stool, high fever, dysentery) and in C. difficile infection. Dose: 4 mg loading, then 2 mg after each loose stool, up to 16 mg/day.

Sources

  1. American Journal of Gastroenterology: ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults (2016)
  2. IDSA: Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea (2017)
  3. Journal of Clinical Gastroenterology: Acute Diarrhea in Adults and Children (2013)
  4. Archives of Family Medicine: Loperamide-Simethicone vs Loperamide Alone, Simethicone Alone, and Placebo in the Treatment of Acute Diarrhea With Gas-Related Abdominal Discomfort: A Randomized Controlled Trial (1999)
  5. Drugs in R&D: Comparison of Two Forms of Loperamide–Simeticone and a Probiotic Yeast (Saccharomyces boulardii) in the Treatment of Acute Diarrhoea in Adults: A Randomised Non-Inferiority Clinical Trial (2015)

ICD-10: A09 · ICD-11: ME05.1

B

Irritable bowel syndrome

Individual decision

In IBS with diarrhea (IBS-D), as-needed loperamide per 2021 reduces diarrheal episodes and improves stool consistency. It does not affect pain frequency or overall quality of life – other classes are needed (rifaximin, eluxadoline, antispasmodics). Use 2 mg 1–4 times daily as needed.

Sources

  1. ACG: ACG clinical guideline: management of irritable bowel syndrome (2021)
  2. Gastroenterology: AGA Clinical Practice Guideline on the Pharmacological Management of Irritable Bowel Syndrome With Diarrhea. (2022)
  3. Scand J Gastroenterol: A double-blind placebo-controlled trial with loperamide in irritable bowel syndrome. (1996)
  4. Scand J Gastroenterol Suppl: Loperamide treatment of the irritable bowel syndrome. (1987)

ICD-10: K58.8 · ICD-11: DD91.0Z

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

F

Hangover recovery

Not recommended

Loperamide is taken as a stool-firming aid after binge drinking and for hangover-related diarrhea, relying on rapid opioid-mediated suppression of bowel motility. (2017) and ASAM (2020) acute alcohol intoxication guidelines, as well as the Pittler 2005 Cochrane review on hangover, do not mention loperamide. Quality RCTs for alcohol-related diarrhea are absent and the evidence base for this indication is missing. High-dose loperamide in opioid-tolerant users causes arrhythmias and QT prolongation ( Drug Safety Communication 2016), so casual self-dosing carries real risk.

Sources

  1. Cochrane: Interventions for preventing or treating alcohol hangover (2005)
  2. Canadian Journal of Cardiology: Loperamide Cardiac Toxicity: Pathophysiology, Presentation, and Management (2022)
  3. Journal of the American Pharmacists Association: Adverse event detection using the FDA post-marketing drug safety surveillance system: Cardiotoxicity associated with loperamide abuse and misuse (2017)
  4. BMJ Case Reports: Loperamide-induced cardiotoxicity: a case overlooked? (2021)

ICD-11: MG49

How to read tiers A–F
  • AStrong evidence – first or second line in international guidelines
  • BRecommended in selected cases
  • CStudy data contradict each other
  • DBenefit not proven, no documented harm
  • FDocumented harm, or risk without benefit

Mechanism of action

Selective peripheral μ-opioid receptor agonist on longitudinal and circular intestinal smooth muscle. Slows peristalsis, prolongs intestinal transit, and increases water and electrolyte reabsorption. Does not cross the blood-brain barrier at therapeutic doses — no central opioid effect. With abuse at high doses (over 20 mg/day) it can cross the BBB, causing opioid toxicity and cardiotoxicity.

Safety

Boxed warning

FDA boxed warning (2018): loperamide at doses far exceeding recommended levels can cause severe cardiac events — QT prolongation, ventricular arrhythmias, torsades de pointes, and cardiac arrest. Cases occur in patients taking high doses for self-treatment of opioid dependence or to obtain euphoria.

Contraindications

  • Age under 4 years
  • Acute dysentery (bloody stools, fever)
  • Acute ulcerative colitis, pseudomembranous colitis
  • Intestinal obstruction, megacolon
  • Hypersensitivity

Serious adverse effects

  • QT prolongation, ventricular arrhythmias, torsades de pointes (with abuse)
  • Toxic megacolon in invasive enteric infection
  • Paralytic ileus

Common adverse effects

  • Constipation after diarrhea resolution
  • Flatulence, abdominal pain
  • Nausea

Pregnancy: can you take Loperamide?

FDA categories were retired in 2015. Use in pregnancy on strict indication. Diarrhea management is rehydration first.

Breastfeeding: can you take Loperamide?

Excreted in milk in minimal amounts. Compatible with breastfeeding per LactMed.

Calculate RIDFull profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Safety concerns

Per 2016 and , loperamide is contraindicated in invasive diarrhea (bloody stools, fever above 38.5 °C, severe systemic illness) — slowing transit promotes pathogen translocation and toxic megacolon. Not used in children under 4; use with caution under medical supervision in children 4–12.

Timing and administration

Take as needed after each loose stool. Do not exceed 16 mg/day in adults (8 mg/day in elderly). If diarrhea persists beyond 48 hours or fever, bloody stools, or severe systemic illness develop, seek urgent medical care.

Common myths

Myth: 'loperamide is a routine safe OTC drug — you can take a lot'. Fact: at doses above 20 mg/day loperamide crosses the BBB and produces opioid euphoria. updated the loperamide black box in 2018 — abuse cases (suicidal abuse) are associated with QT prolongation, ventricular arrhythmias, and cardiac arrest. Suspected abuse warrants ECG.

Myth: 'loperamide is for any diarrhea in a child'. Fact: it is not used in children under 4 — risk of severe ileus and toxic megacolon. Pediatric diarrhea is managed with oral rehydration and zinc ().
Label mentions13 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

  • ModerateGemfibrozil
    «Drug Interactions: Concomitant use of loperamide hydrochloride capsules with inhibitors of CYP3A4 (e.g., itraconazole) or CYP2C8 (e.g., gemfibrozil) or inhibitors of P-glycoprotein (e.g., quinidine…»

    FDA, section 7 · Open on DailyMed

  • ModerateItraconazole
    «Drug Interactions: Concomitant use of loperamide hydrochloride capsules with inhibitors of CYP3A4 (e.g., itraconazole) or CYP2C8 (e.g., gemfibrozil) or inhibitors of P-glycoprotein (e.g., quinidine…»

    FDA, section 7 · Open on DailyMed

  • ModerateQuinidine
    «Drug Interactions: Concomitant use of loperamide hydrochloride capsules with inhibitors of CYP3A4 (e.g., itraconazole) or CYP2C8 (e.g., gemfibrozil) or inhibitors of P-glycoprotein (e.g., quinidine…»

    FDA, section 7 · Open on DailyMed

  • ModerateRitonavir
    «Drug Interactions: Concomitant use of loperamide hydrochloride capsules with inhibitors of CYP3A4 (e.g., itraconazole) or CYP2C8 (e.g., gemfibrozil) or inhibitors of P-glycoprotein (e.g., quinidine…»

    FDA, section 7 · Open on DailyMed

  • CYP3A4 inhibitorsclass named in the label
    «Drug Interactions: CYP3A4 Inhibitors»

    FDA, section 7 · Open on DailyMed

  • Gemfibrozil
    «La administración concomitante de hidrocloruro de loperamida (dosis única de 4 mg) e itraconazol, un inhibidor de la CYP3A4 y la glucoproteína P, causó un aumento que triplicó o cuadruplicó las…»

    AEMPS, section 4.5 · Open on CIMA

  • Itraconazole
    «La administración concomitante de hidrocloruro de loperamida (dosis única de 4 mg) e itraconazol, un inhibidor de la CYP3A4 y la glucoproteína P, causó un aumento que triplicó o cuadruplicó las…»

    AEMPS, section 4.5 · Open on CIMA

  • Ketoconazole
    «La administración concomitante de hidrocloruro de loperamida (dosis única de 16 mg) y ketoconazol, un inhibidor de la CYP3A4 y la glucoproteína P, causó un aumento que quintuplicó las concentraciones…»

    AEMPS, section 4.5 · Open on CIMA

  • Quinidine
    «Los datos preclínicos han demostrado que el hidrocloruro de loperamida es un sustrato de la glucoproteína P. La administración concomitante de hidrocloruro de loperamida (dosis única de 16 mg) con…»

    AEMPS, section 4.5 · Open on CIMA

  • Ritonavir
    «Los datos preclínicos han demostrado que el hidrocloruro de loperamida es un sustrato de la glucoproteína P. La administración concomitante de hidrocloruro de loperamida (dosis única de 16 mg) con…»

    AEMPS, section 4.5 · Open on CIMA

From other drugs’ labels

  • ModerateGemfibrozil
    «El perfil de interacciones de gemfibrozilo es complejo. Los estudios in vivo indican que gemfibrozilo y su metabolito gemfibrozilo 1-O-β-glucurónido son potentes inhibidores de CYP2C8 (un enzima…»

    AEMPS, section 4.5 · Open on CIMA

  • Itraconazole
    «Medicamentos usados en diabetes: Aprepitant, Loperamida, Netupitant»

    AEMPS, section 4.5 · Open on CIMA

  • Meperidine
    «Antidiarreicos y agentes antiperistálticos (tales como loperamida y caolín): su uso simultáneo puede aumentar el riesgo de un estreñimiento severo.»

    AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Loperamide used for?

Loperamide is evaluated for the following indications with varying evidence strength: Travelers' diarrhea (evidence tier A), Irritable bowel syndrome (evidence tier B), Acute diarrhea in adults (evidence tier B). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Loperamide?

Common side effects of Loperamide (≥ 1 in 100): Constipation after diarrhea resolution, Flatulence, abdominal pain, Nausea. See the Safety section for uncommon and serious reactions.

Is Loperamide safe during pregnancy?

FDA categories were retired in 2015. Use in pregnancy on strict indication. Diarrhea management is rehydration first.

Is Loperamide compatible with breastfeeding?

Excreted in milk in minimal amounts. Compatible with breastfeeding per LactMed.

Who should not take Loperamide?

Loperamide is contraindicated in: Age under 4 years; Acute dysentery (bloody stools, fever); Acute ulcerative colitis, pseudomembranous colitis; Intestinal obstruction, megacolon; Hypersensitivity. Full list in the Safety section.

Does Loperamide carry an FDA boxed warning?

FDA boxed warning (2018): loperamide at doses far exceeding recommended levels can cause severe cardiac events — QT prolongation, ventricular arrhythmias, torsades de pointes, and cardiac arrest. Cases occur in patients taking high doses for self-treatment of opioid dependence or to obtain euphoria.

loperamide is a routine safe OTC drug — you can take a lot

at doses above 20 mg/day loperamide crosses the BBB and produces opioid euphoria. FDA updated the loperamide black box in 2018 — abuse cases (suicidal abuse) are associated with QT prolongation, ventricular arrhythmias, and cardiac arrest. Suspected abuse warrants ECG.

loperamide is for any diarrhea in a child

it is not used in children under 4 — risk of severe ileus and toxic megacolon. Pediatric diarrhea is managed with oral rehydration and zinc (WHO).

Official sources

Direct links to regulator labels. Open in a new tab.

Other drugs in this group

Mesalazine, Nifuroxazide, Nystatin, Probiotics (Lactobacillus spp., Bifidobacterium spp., Saccharomyces boulardii), Berberine, Curcumin (Curcuma longa extract), Saccharomyces boulardii CNCM I-745, Sulfasalazine