Ofloxacin and Alosetron: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Alosetron
No brand names on recordOfloxacin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased plasma concentration and half-life of alosetron
Interaction Deep Dive
Concomitant use of alosetron, a CYP1A2 substrate, and fluvoxamine, a strong CYP1A2 inhibitor, resulted in increased plasma concentrations and a prolonged half-life of alosetron. The probable mechanism of this interaction is inhibition of CYP1A2-mediated alosetron metabolism by fluvoxamine. Although not studied, coadministration of alosetron and moderate CYP1A2 inhibitors, such as fluoroquinolones, may also result in an increased concentration and half-life of alosetron. Therefore, coadministration of alosetron and moderate CYP1A2 inhibitors, including ofloxacin, should be avoided unless clinically necessary1. If coadministration is clinically necessary, consider monitoring patients for increased alosetron adverse effects such as constipation, increased abdominal discomfort, and ischemic colitis.
Why it happens (mechanism)
Inhibition of CYP1A2-mediated alosetron metabolism by ofloxacin
Literature reports
1 report — tap to read
a) Concomitant use of alosetron, a CYP1A2 substrate, and fluvoxamine, a strong CYP1A2 inhibitor, resulted in increased plasma concentrations and a prolonged half-life of alosetron. Healthy female volunteers (n=40) were given escalating doses of fluvoxamine (50 to 200 mg/day) for 16 days, with concomitant use of alosetron 1 mg on day 16. Mean alosetron plasma concentrations increased approximately 6-fold while the alosetron half-life increased approximately 3-fold 1.
Common questions
Can I take Ofloxacin and Alosetron together?
Increased plasma concentration and half-life of alosetron Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ofloxacin and Alosetron interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Ofloxacin or Alosetron need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: LOTRONEX(R) oral tablets, alosetron hcl oral tablets. Prometheus Laboratories,Inc, San Diego, CA, 2008. DailyMed
Keep reading about Alosetron
Keep reading about Ofloxacin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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