Prescription medicine
Alosetron Brand names: Lotronex
Alosetron (Lotronex) is a prescription medicine with an FDA approval on record since 2000. FDA's NDC Directory lists it from 6 generic labelers, and pharmacies paid $2.02 per alosetron HCl 0.5 mg tablet in the October 7, 2026 NADAC survey.
- Generic listed
- Boxed warning
Check it at the source: the alosetron FDA label on DailyMed (effective March 23, 2026, Legacy Pharma USA Inc.); the NDA 21107 record on Drugs@FDA; every alosetron label on DailyMed.
Highlights of the record
FDA label of March 23, 2026; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026; NADAC October 7, 2026
SERIOUS GASTROINTESTINAL ADVERSE REACTIONS.
Infrequent but serious gastrointestinal adverse reactions have been reported with the use of LOTRONEX. These events, including ischemic colitis and serious complications of constipation, have resulted in hospitalization, and rarely, blood transfusion, surgery, and death. LOTRONEX is indicated only for women with severe diarrhea-predominant irritable bowel syndrome (IBS) who have not responded adequately to conventional therapy [see Indications and Usage ( 1 )]. LOTRONEX should be discontinued immediately in patients who develop constipation or symptoms of ischemic colitis. Patients should immediately report constipation or symptoms of ischemic colitis to their prescriber. LOTRONEX should not be resumed in patients who develop ischemic colitis. Patients who have constipation should immediately contact their prescriber if the constipation does not resolve after LOTRONEX is discontinued. Patients with resolved constipation should resume LOTRONEX only on the advice of their treating prescriber [see Dosage and Administration ( 2.1 ), Warnings and Precautions ( 5.1 ), ( 5.2 )]. WARNING: SERIOUS GASTROINTESTINAL ADVERSE REACTIONS See full prescribing information for complete boxed warning. Infrequent but serious gastrointestinal adverse reactions have been reported with the use of LOTRONEX. […]
Used for
From the label: indications and usageLOTRONEX is indicated only for women with severe diarrhea-predominant irritable bowel syndrome (IBS) who have: chronic IBS symptoms (generally lasting 6 months or longer), had anatomic or biochemical abnormalities of the gastrointestinal tract excluded, and not responded adequately to conventional therapy.
Forms and strengths
- 0.5 mg
- 1 mg
Tablet; film-coated tablet.
On the market
- Earliest approval on file
- February 9, 2000 Lotronex, Legacy; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 6 first May 4, 2015; 4 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 8 of which 6 under generic applications, 2 under brand applications, repackagers included
Supply and safety
- Pharmacy cost (NADAC)
- $2.02 per tablet Alosetron HCl 0.5 mg tablet
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- No recall recorded
- FAERS reports
- 908 through July 30, 2026
What is alosetron used for?
From the label: indications and usageLOTRONEX is indicated only for women with severe diarrhea-predominant irritable bowel syndrome (IBS) who have: chronic IBS symptoms (generally lasting 6 months or longer), had anatomic or biochemical abnormalities of the gastrointestinal tract excluded, and not responded adequately to conventional therapy. Diarrhea-predominant IBS is severe if it includes diarrhea and one or more of the following: frequent and severe abdominal pain/discomfort, frequent bowel urgency or fecal incontinence, disability or restriction of daily activities due to IBS. […]
FDA pharmacologic class: Serotonin-3 Receptor Antagonist.
Source: FDA drug label (LOTRONEX), Legacy Pharma USA Inc., effective March 23, 2026 (SPL set c216e967-436f-475a-8e6a-2ad11adc63af), via openFDA; the full label on DailyMed
What does the patient leaflet for alosetron say first?
The FDA-approved Medication Guide or Patient Information that comes with the medicine, in its own words.
From the patient leaflet: What is the most important information I should know about LOTRONEX?LOTRONEX is a medicine only for some women with severe chronic irritable bowel syndrome (IBS) whose: main problem is diarrhea and IBS symptoms have not been helped enough by other treatments. Some people have developed serious bowel side effects while taking LOTRONEX. Serious bowel (intestine) side effects can happen suddenly, including the following: Serious complications of constipation: These complications may lead to a hospital stay and, in rare cases, blood transfusions, surgery, and death. People who are older, who are weak from illness, or who take other constipating medicines may be more likely to have serious complications of constipation with LOTRONEX. To lower your chances of getting serious complications of constipation, do the following: If you are constipated, do not start taking LOTRONEX. If you get constipated while taking LOTRONEX , stop taking it right away and call your doctor. If your constipation does not get better after stopping LOTRONEX , call your doctor again. If you stopped taking LOTRONEX, do not start taking LOTRONEX again unless your doctor tells you to do so. Inflammation and injury of the intestines caused by reduced blood flow (ischemic colitis): Ischemic colitis is caused by reduced blood flow to parts of the large bowel. The chance of getting ischemic colitis when you take LOTRONEX for more than 6 months is not known. Ischemic colitis may lead to a hospital stay and, in rare cases, blood transfusions, surgery, and death. Stop taking LOTRONEX and call your doctor or get medical help if you have symptoms of ischemic colitis such as new or worsening stomach-area (abdominal) pain, bloody diarrhea or blood in the stool.
From the patient leaflet: How should I store LOTRONEX?Store LOTRONEX at room temperature between 68ºF to 77ºF (20ºC to 25ºC). Protect LOTRONEX from light and moisture. Keep LOTRONEX and all medicines out of the reach of children.
Source: FDA drug label (LOTRONEX), Legacy Pharma USA Inc., effective March 23, 2026 (SPL set c216e967-436f-475a-8e6a-2ad11adc63af), via openFDA; the full label on DailyMed
Is there a generic for alosetron (Lotronex)?
The FDA approved the first generic alosetron on May 4, 2015. 6 generic applications are approved; 4 of them carry a current (not discontinued) marketing status in Drugs@FDA; that status is not evidence that the generic is on sale.
FDA's NDC Directory lists alosetron from 6 labelers under a generic (ANDA) application and from 2 brand labelers. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it.
- 2000 earliest approval on file
- 2015 first generic approved
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
What do pharmacies pay for alosetron (Lotronex)?
In CMS's NADAC survey of October 7, 2026, pharmacies paid $2.02 per Alosetron HCl 0.5 mg tablet, down 15% from $2.38 on October 8, 2025. The chart's scale runs from the lowest to the highest price shown, not from zero. NADAC is what retail pharmacies paid their wholesalers, per unit, in CMS's monthly survey; what a patient pays depends on insurance and the pharmacy.
- Alosetron HCl 0.5 mg tablet (generic)
| Strength and form | Brand or generic | Pharmacy cost | 30 tablets, or one pen or vial | 12-month change |
|---|---|---|---|---|
| Alosetron HCl 0.5 mg tablet | Generic | $2.02 per tablet | $60.56 | -15% |
| Alosetron HCl 1 mg tablet | Generic | $3.42 per tablet | $102.59 | -12% |
Source: CMS National Average Drug Acquisition Cost (NADAC) survey, October 7, 2026: what retail pharmacies paid per unit; not a counter price
What does the alosetron label say about other medicines?
The alosetron label names 11 other medicines in its interaction, contraindication or warning sections. The labels of 7 other medicines name alosetron. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Cimetidine | drug interactions | Concomitant administration of alosetron and moderate CYP1A2 inhibitors, including quinolone antibiotics and cimetidine, has not been evaluated, but should be avoided unless clinically necessary because of similar potential drug interactions. |
| Clarithromycin | 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. |
| Fluvoxamine | contraindications | Use of Fluvoxamine Concomitant administration of LOTRONEX with fluvoxamine is contraindicated. |
| Hydralazine | drug interactions | Although not studied with alosetron, inhibition of N-acetyltransferase may have clinically relevant consequences for drugs such as isoniazid, procainamide, and hydralazine. |
| Isoniazid | drug interactions | Although not studied with alosetron, inhibition of N-acetyltransferase may have clinically relevant consequences for drugs such as isoniazid, procainamide, and hydralazine. |
| Itraconazole | 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. |
| Ketoconazole | drug interactions | Ketoconazole is a known strong inhibitor of CYP3A4. |
| Levonorgestrel | drug interactions | Another study showed that alosetron had no clinically significant effect on plasma concentrations of the oral contraceptive agents ethinyl estradiol and levonorgestrel (CYP3A4 substrates). |
| Procainamide | drug interactions | Although not studied with alosetron, inhibition of N-acetyltransferase may have clinically relevant consequences for drugs such as isoniazid, procainamide, and hydralazine. |
| Theophylline | drug interactions | The effect on CYP1A2 was explored further in a clinical interaction study with theophylline and no effect on metabolism was observed. |
| Voriconazole | 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. |
Other labels that name alosetron
Source: FDA drug label (LOTRONEX), Legacy Pharma USA Inc., effective March 23, 2026 (SPL set c216e967-436f-475a-8e6a-2ad11adc63af), via openFDA; the full label on DailyMed
What do FAERS reports show for alosetron?
The FDA Adverse Event Reporting System holds 908 reports that list alosetron among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 47 are coded as a death and 211 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
Reports received each year
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What next?
- Other serotonin-3 receptor antagonists
- the pharmacologic class, with prices and generics
- Alosetron side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other