Alosetron and Fluvoxamine interaction
Alosetron and Fluvoxamine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Alosetron (LOTRONEX) label · effective 2026-06-30
…obstruction, stricture, toxic megacolon, gastrointestinal perforation, and/or adhesions ischemic colitis, impaired intestinal circulation, thrombophlebitis, or hypercoagulable state Crohn's disease or ulcerative colitis diverticulitis severe hepatic impairment 4.3 Concomitant Use of Fluvoxamine Concomitant administration of LOTRONEX with fluvoxamine is contraindicated.
Use with fluvoxamine is contraindicated.
Concomitant administration of alosetron and fluvoxamine is contraindicated [see Contraindications ( 4.3 )] .
Fluvoxamine, a known strong inhibitor of CYP1A2, has been shown to increase mean alosetron plasma concentrations (AUC) approximately 6-fold and prolong the half-life by approximately 3-fold [see Drug Interactions ( 7.1 )] .
From the Fluvoxamine (fluvoxamine maleate) label · effective 2026-04-23
Coadministration Coadministration of tizanidine, thioridazine, alosetron, or pimozide with Fluvoxamine Maleate Tablets is contraindicated [see Warnings and Precautions ( 5.4 , 5.5 , 5.6 , 5.7 )] .
In a pharmacokinetic study, 40 healthy female subjects received fluvoxamine in escalating doses from 50 mg to 200 mg a day for 16 days, with coadministration of alosetron 1 mg on the last day.
Fluvoxamine increased mean alosetron plasma concentration (AUC) approximately 6-fold and prolonged the half-life by approximately 3-fold. [See Contraindications ( 4 ) and Lotronex TM (alosetron) package insert] .
Other Drugs Alosetron: See Contraindications ( 4 ), Warnings and Precautions ( 5.7 ) , and Lotronex TM (alosetron) package insert.
Potential Alosetron Interaction Because alosetron is metabolized by a variety of hepatic CYP drug metabolizing enzymes, inducers or inhibitors of these enzymes may change the clearance of alosetron.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.