Fluvoxamine blocks four liver enzymes: five drugs are contraindicated with it, and alprazolam levels double
The fluvoxamine label contraindicates thioridazine, tizanidine, pimozide, alosetron and ramelteon. With alprazolam, plasma concentrations "were approximately twice those observed when alprazolam was administered alone."
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: The alprazolam and propranolol figures are from small volunteer studies cited in the label at fluvoxamine 100 mg; the label notes the interaction "may be more pronounced" at 300 mg and was not studied there.
Fluvoxamine is the SSRI most often chosen for OCD, and the one with the longest list of drugs it makes stronger.
Significant findings
Fluvoxamine maleate extended-release prescribing information (Upsher-Smith, September 2026), Contraindications: "Coadministration of thioridazine, tizanidine, pimozide, alosetron, or ramelteon with fluvoxamine maleate extended-release capsules are contraindicated". MAOIs are contraindicated within 14 days in either direction, and the label adds: "do not start fluvoxamine maleate extended-release capsules in a patient who is being treated with linezolid or intravenous methylene blue".
Section 7: "Fluvoxamine inhibits several cytochrome P450 isoenzymes (CYP1A2, CYP2C9, CYP3A4, and CYP2C19)". Section 5.9 on benzodiazepines: "Benzodiazepines metabolized by hepatic oxidation (e.g., alprazolam, midazolam, triazolam, etc.) should be used with caution because the clearance of these drugs is likely to be reduced by fluvoxamine. The clearance of benzodiazepines metabolized by glucuronidation (e.g., lorazepam, oxazepam, temazepam) is unlikely to be affected". With alprazolam 1 mg four times a day plus fluvoxamine 100 mg, "plasma concentrations and other pharmacokinetic parameters (AUC, Cmax, T1/2) of alprazolam were approximately twice those observed when alprazolam was administered alone; oral clearance was reduced by about 50%. The elevated plasma alprazolam concentrations resulted in decreased psychomotor performance and memory."
Other listed interactions: "Carbamazepine: Elevated carbamazepine levels and symptoms of toxicity with coadministration." "Tricyclic Antidepressants (TCAs): Coadministration significantly increased plasma TCA levels." "Propranolol or Metoprolol: Reduce dose if coadministered with fluvoxamine and titrate more cautiously." Propranolol trough levels rose fivefold. Clozapine is covered on its own label: dose cut to a third. Smokers metabolise fluvoxamine 25 percent faster.
Worth asking
Fluvoxamine's interactions run through the enzymes, which means the list is not closed: any drug cleared by CYP1A2 or CYP3A4, including caffeine, some antipsychotics and some sleeping tablets, may be affected. If you take fluvoxamine, the question for a pharmacist is a full check of everything else you take, and the benzodiazepine question in particular: lorazepam and oxazepam are the ones the label says are unaffected.
Source
Fluvoxamine maleate extended-release capsules: FDA-approved prescribing information, Contraindications 4, Warnings and Precautions 5.9, Drug Interactions 7.1 to 7.4 — Upsher-Smith Laboratories, LLC; US Food and Drug Administration (2026)
Regulator or national health body
How this was scored
- Study design
- Regulatory safety determination
- Funding
- Industry funded
- Published in
- Regulator or national health body
- Sample size
- not recorded
- Preregistered
- not recorded
- Conflicts disclosed
- not recorded
- Independent of proponent
- not recorded
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published September 21, 2026.
Questions
How strong is the evidence behind this?
veisund rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 57 out of 100 on our published rubric. One caveat travels with that badge: The alprazolam and propranolol figures are from small volunteer studies cited in the label at fluvoxamine 100 mg; the label notes the interaction "may be more pronounced" at 300 mg and was not studied there. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Fluvoxamine maleate extended-release capsules: FDA-approved prescribing information, Contraindications 4, Warnings and Precautions 5.9, Drug Interactions 7.1 to 7.4 — Upsher-Smith Laboratories, LLC; US Food and Drug Administration (2026). Published in: Regulator or national health body. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Regulatory safety determination. Funding: Industry funded. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.