Prescription medication · 5-HT3 Antagonist (IBS-D)
alosetron
Also sold as Lotronex. Alosetron is used to treat severe diarrhea-predominant irritable bowel syndrome (IBS) in women.
Data updated 2026-05-15
- 73
- FDA reportsRarely reported
- 12
- InteractionsSeveral interactions
- $2.42
- Generic price (NADAC)
What the data shows
alosetron (Lotronex) is a prescription 5-HT3 Antagonist (IBS-D), among the least-reported drugs the FDA tracks (73 FDA reports), with 12 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.
alosetron (Lotronex) is a prescription 5-HT3 Antagonist (IBS-D). Alosetron is used to treat severe diarrhea-predominant irritable bowel syndrome (IBS) in women.
Alosetron (Lotronex) is a medicine for women with severe diarrhea-predominant irritable bowel syndrome (IBS). It helps to reduce diarrhea and stomach pain.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$2.42/unit
Generic Available
Yes (3 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Alosetron is used to treat severe diarrhea-predominant irritable bowel syndrome (IBS) in women.
Common side effects
Constipation, Abdominal discomfort and pain, Nausea
Key warnings
Alosetron can cause serious gut problems, like ischemic colitis (reduced blood flow to the bowel) and severe constipation.
The sections below are summarized in plain English from alosetron's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Alosetron blocks a substance called serotonin in your gut. Serotonin can speed up bowel movements. By blocking serotonin, alosetron slows down your bowel and reduces diarrhea.
Side Effects (from patient reports)
Based on 73 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for alosetron, by number of reports
- Diarrhoea
Diarrhoea
10 reports
- Nausea
Nausea
8 reports
- Abdominal Pain
Abdominal Pain
6 reports
- Death
Death
6 reports
- Constipation
Constipation
5 reports
- Fatigue
Fatigue
5 reports
- Pain
Pain
5 reports
- Asthenia
Asthenia
4 reports
- Condition Aggravated
Condition Aggravated
4 reports
- Illness
Illness
4 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 alosetron 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 alosetron sits
alosetron has more FDA adverse-event reports than 1% 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 alosetron; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 73 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
73
Reports Mentioning Death
8
11.0% of reports — not proof of cause
Hospitalization Reports
18
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | DIARRHOEA | 10 |
| 3 | NAUSEA | 8 |
| 5 | ABDOMINAL PAIN | 6 |
| 6 | DEATH | 6 |
| 7 | CONSTIPATION | 5 |
| 8 | FATIGUE | 5 |
| 9 | PAIN | 5 |
| 10 | ASTHENIA | 4 |
| 11 | CONDITION AGGRAVATED | 4 |
| 12 | ILLNESS | 4 |
| 13 | MUSCLE SPASMS | 4 |
| 15 | VOMITING | 4 |
| 16 | COLITIS ISCHAEMIC | 3 |
| 17 | COVID-19 | 3 |
| 18 | DECREASED APPETITE | 3 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Alosetron can cause serious gut problems, like ischemic colitis (reduced blood flow to the bowel) and severe constipation. These problems can lead to hospitalization, surgery, or even death. Stop taking alosetron right away if you get constipated or have symptoms of ischemic colitis, like bloody diarrhea or bad stomach pain. Call your doctor immediately.
Known Drug Interactions
Coadministration of alosetron and strong CYP3A4 inhibitors such as clarithromycin, telithromycin, protease inhibitors, voriconazole, and itraconazole has not been evaluated but should be undertaken with caution because of similar potential drug interactions.
Mechanism: Clarithromycin blocks the enzymes that break down alosetron, which could lead to higher levels of alosetron in your body.
Coadministration of alosetron and strong CYP3A4 inhibitors such as clarithromycin, telithromycin, protease inhibitors, voriconazole, and itraconazole has not been evaluated but should be undertaken with caution because of similar potential drug interactions.
Mechanism: Itraconazole may block the liver enzymes that break down alosetron, which could lead to higher levels of the drug in your body.
Coadministration of alosetron and strong CYP3A4 inhibitors such as clarithromycin, telithromycin, protease inhibitors, voriconazole, and itraconazole has not been evaluated but should be undertaken with caution because of similar potential drug interactions.
Mechanism: Voriconazole can slow down how your body processes alosetron, potentially causing the medication to build up in your system.
Another study showed that alosetron had no clinically significant effect on plasma concentrations of the oral contraceptive agents ethinyl estradiol and levonorgestrel (CYP3A4 substrates).
Mechanism: Alosetron does not seem to change the amount of estradiol in your blood.
Although not studied with alosetron, inhibition of N-acetyltransferase may have clinically relevant consequences for drugs such as isoniazid, procainamide, and hydralazine.
Mechanism: Alosetron may interfere with the way your body processes hydralazine, potentially leading to higher drug levels.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
Can men take alosetron?
What should I do if I get constipated while taking alosetron?
Can I take alosetron if I have liver problems?
Can I take alosetron with other medicines?
How long does it take for alosetron to start working?
What are the symptoms of ischemic colitis?
What should I do if my constipation does not resolve after stopping alosetron?
Can I drive or operate machinery while taking alosetron?
What do the alosetron tablets look like?
How should I dispose of unused alosetron tablets?
What are the common side effects of alosetron?
Does alosetron interact with other medications?
What drug class is alosetron?
What pregnancy or breastfeeding source fields are listed for alosetron?
Related Medications in 5-HT3 Antagonist (IBS-D)
Other drugs grouped near alosetron - same-class peers and common alternatives.
aprepitant
Emend
Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting.
Compare with alosetron →
bisacodyl
Dulcolax
Bisacodyl is a medicine that helps you have a bowel movement.
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bismuth subsalicylate
Pepto-Bismol
Bismuth subsalicylate (Pepto-Bismol) is a medicine that can treat diarrhea and upset stomach.
Compare with alosetron →
cimetidine
Tagamet
Cimetidine (Tagamet) reduces stomach acid.
Compare with alosetron →
dexlansoprazole
Dexilant
Dexlansoprazole (Dexilant) is a medicine that lowers stomach acid.
Compare with alosetron →
Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for alosetron: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 73.
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 10.96%.
- ticagrelor Δ 0.01 pts · 30,895 reports · P2Y12 Inhibitor (Antiplatelet) 10.95%death share
- perphenazine Δ 0.02 pts · 2,013 reports · Typical Antipsychotic (Phenothiazine) 10.98%death share
- amlodipine Δ 0.05 pts · 257,862 reports · Calcium Channel Blocker 10.91%death share
- fidaxomicin Δ 0.05 pts · 2,273 reports · Macrocyclic Antibiotic 10.91%death share
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for alosetron
The FDA label for alosetron (sold under brand names such as Lotronex) classifies it as a prescription-only medication in the 5-HT3 Antagonist (IBS-D) class. Alosetron is used to treat severe diarrhea-predominant irritable bowel syndrome (IBS) in women. Official labeling lists 4 commonly reported side effects, including Constipation, Abdominal discomfort and pain, Nausea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 73 voluntary reports. The database also lists 12 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 $2.42.
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, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
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. This registry does not provide medication decisions.
Last updated: October 1, 2025
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
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 from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
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