loperamide
Brand names: Imodium
Loperamide (Imodium) helps control diarrhea symptoms. It is also used for Traveler's Diarrhea.
Drug Pricing (NADAC)
Generic Price
$0.03/unit
Generic Available
Yes (23 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats diarrhea.
Common side effects
Headache, Dizziness, Constipation
Key warnings
Taking too much loperamide can cause serious heart problems.
How It Works
Loperamide works by slowing down your intestines. This allows more water to be absorbed from your stool. This makes your stools less watery and reduces how often you need to go to the bathroom.
How to Take It
Drink plenty of clear fluids to avoid dehydration. Use the dosing cup that comes with the medicine. Shake the bottle well before each use. Follow the dosage chart to find the right dose based on your weight or age.
Pregnancy & Breastfeeding
Talk to your doctor before taking this medicine if you are pregnant or breastfeeding. It is not known if loperamide can harm your unborn baby or pass into breast milk.
Missed Dose
Take the next dose after your next loose stool. Do not take more medicine than the maximum daily dose.
Storage
Store between 68-77°F (20-25°C).
Side Effects (from patient reports)
Based on 34,073 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 42,665 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 1999–2025.
Total Reports
42,665
Death-Related Reports
3,775
Hospitalization Reports
15,486
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DIARRHOEA | 8,463 |
| 2 | NAUSEA | 4,092 |
| 3 | DRUG INEFFECTIVE | 3,915 |
| 4 | FATIGUE | 3,690 |
| 5 | OFF LABEL USE | 3,095 |
| 6 | VOMITING | 2,674 |
| 7 | CONSTIPATION | 2,352 |
| 8 | WEIGHT DECREASED | 2,018 |
| 9 | HEADACHE | 1,890 |
| 10 | DYSPNOEA | 1,879 |
| 11 | ABDOMINAL PAIN | 1,759 |
| 12 | ASTHENIA | 1,745 |
| 13 | DECREASED APPETITE | 1,712 |
| 14 | DIZZINESS | 1,615 |
| 15 | PAIN | 1,595 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Taking too much loperamide can cause serious heart problems. Always follow the recommended dose.
Known Drug Interactions
Examples: cyclosporine, gemfibrozil, antiretrovirals (atazanavir, lopinavir, ritonavir, saquinavir, tipranavir), rifampin, eltrombopag Drugs that Cause Constipation Clinical Impact: Increased risk for constipation related adverse reactions and potential for constipation related serious adverse reactions Intervention: Avoid use with other drugs that may cause constipation (see below); loperamide may be used occasionally for acute management of severe diarrhea but avoid chronic use. Discontinue loperamide immediately if constipation occurs.
Mechanism: These medicines both work to slow down your bowels, and using them together can cause dangerous levels of constipation.
What to do: Do not use loperamide long-term with this drug, and stop it immediately if you become constipated.
Aprepitant Loperamide a Monitor for adverse reactions.
Mechanism: Itraconazole can stop your body from breaking down loperamide properly, leading to higher levels of the medicine in your blood.
What to do: You should be monitored for any unusual reactions or side effects.
Common Questions
How much should I take?
Can I use a regular spoon to measure the dose?
What should I do if I still have diarrhea after taking this medicine?
Can I take this medicine if I have a fever?
Can I take this with other medicines?
What is the maximum amount I can take in a day?
Can children under 2 years old take this medicine?
What do I do if I accidentally take too much?
Does this medicine expire?
Can I drive while taking this medicine?
What are the common side effects of loperamide?
Does loperamide interact with other medications?
What drug class is loperamide?
Is loperamide safe during pregnancy?
Has loperamide been recalled?
Active Recalls
CGMP Deviations: product held outside appropriate storage temperature conditions.
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Related Medications in Antidiarrheal (Opioid Receptor Agonist)
Other drugs grouped near loperamide — same-class peers and common alternatives.
alosetron
Lotronex
Alosetron (Lotronex) is a medicine for women with severe diarrhea-predominant irritable bowel syndrome (IBS).
Compare with loperamide →
aprepitant
Emend
Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting.
Compare with loperamide →
bisacodyl
Dulcolax
Bisacodyl is a medicine that helps you have a bowel movement.
Compare with loperamide →
bismuth subsalicylate
Pepto-Bismol
Bismuth subsalicylate (Pepto-Bismol) is a medicine that can treat diarrhea and upset stomach.
Compare with loperamide →
cimetidine
Tagamet
Cimetidine (Tagamet) reduces stomach acid.
Compare with loperamide →
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What the FDA Data Shows for loperamide
The FDA label for loperamide (sold under brand names such as Imodium) classifies it as an over-the-counter product in the Antidiarrheal (Opioid Receptor Agonist) class. This medicine treats diarrhea. Official labeling lists 4 commonly reported side effects, including Headache, Dizziness, Constipation.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 34,073 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $0.03.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history (currently 1 recall record on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: April 11, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages