Over-the-counter medication · Antidiarrheal (Opioid Receptor Agonist)
loperamide
Also sold as Imodium. This medicine treats diarrhea.
Data updated 2026-05-15
- 42,665
- FDA reportsOften reported
- 2
- InteractionsFew interactions
- 1
- Recall record
What the data shows
loperamide (Imodium) is an over-the-counter Antidiarrheal (Opioid Receptor Agonist), reported at a middle-of-the-pack volume (42,665 FDA reports), with 2 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
loperamide (Imodium) is an over-the-counter Antidiarrheal (Opioid Receptor Agonist). This medicine treats diarrhea.
Loperamide (Imodium) helps control diarrhea symptoms. It is also used for Traveler's Diarrhea.
Verify with FDA → · CMS NADAC pricing →
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.
The sections below are summarized in plain English from loperamide's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
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.
This is a plain-language summary of loperamide's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
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.
This is a plain-language summary of loperamide's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
Take the next dose after your next loose stool. Do not take more medicine than the maximum daily dose.
This is a plain-language summary of loperamide's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store between 68-77°F (20-25°C).
Side Effects (from patient reports)
Based on 42,665 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for loperamide, by number of reports
- Diarrhea
Diarrhea
8,466 reports
- Feeling sick to your stomach
Feeling sick to your stomach
4,091 reports
- Feeling tired
Feeling tired
3,692 reports
- Throwing up 2,673
Throwing up
2,673 reports
- Having trouble pooping 2,352
Having trouble pooping
2,352 reports
- Weight loss 2,019
Weight loss
2,019 reports
- Headache 1,890
Headache
1,890 reports
- Difficulty breathing 1,879
Difficulty breathing
1,879 reports
- Stomach pain 1,758
Stomach pain
1,758 reports
- Weakness 1,747
Weakness
1,747 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for loperamide each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where loperamide sits
loperamide has more FDA adverse-event reports than 70% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is loperamide; the line is the median (50th percentile).
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
Reports Mentioning Death
3,775
8.8% of reports — not proof of cause
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 |
| 4 | FATIGUE | 3,690 |
| 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 |
| 16 | PNEUMONIA | 1,545 |
| 17 | DEHYDRATION | 1,533 |
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.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
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 42,665 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.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
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