Ivermectin interaction with tansulosin
Executive summary
There are no specific, documented drug–drug interactions between ivermectin and tamsulosin reported in the sources provided; major ivermectin interaction databases list many potential interacting drugs but do not single out tamsulosin [1] [2]. Mechanistically, ivermectin is a CYP3A4 substrate and a P‑glycoprotein (P‑gp) substrate and is not a known broad CYP or P‑gp inhibitor, which makes a pharmacokinetic interaction with tamsulosin unlikely based on the available pharmacology — but the reporting supplied does not include any direct clinical studies or explicit guidance about this specific pair [3] [4] [5].
1. What the interaction checkers and reviews actually report
Comprehensive interaction checkers and reviews list ivermectin as having many potential interactions (Drugs.com reports 106 drugs, and Stromectol checkers replicate large interaction lists), yet none of the provided snippets identify tamsulosin as a flagged interacting medicine; these resources emphasize the need to tell clinicians about all drugs but do not document a specific ivermectin–tamsulosin interaction in the material supplied [1] [2] [6].
2. The pharmacology that shapes plausible interactions
Pharmacokinetic reviews and drug monographs characterize ivermectin as a substrate of CYP3A4 and of the P‑glycoprotein transporter and note that drugs that inhibit P‑gp or strong CYP3A4 inhibitors can raise ivermectin levels, while certain other agents can lower its concentrations; ivermectin itself is not widely described as inhibiting CYP enzymes or P‑gp in the supplied summaries, making it less likely to raise levels of co‑medications via those pathways [3] [4] [5] [7].
3. Why the absence of tamsulosin in reports matters — and what can't be concluded
The reporting available does not include tamsulosin in its examples or flagged lists, and none of the cited reviews or interaction checkers present clinical studies of coadministration with tamsulosin; therefore it is not possible from these sources to state definitively that no interaction exists, only that no documented, notable interaction appears in these datasets and summaries [1] [4] [8].
4. Clinical-significance logic: why an interaction would be unlikely but not impossible
Because ivermectin’s clinically important interactions cited here center on P‑gp modulation and CYP3A4 inhibition (which can increase ivermectin exposure), and because the provided sources emphasize interactions with strong CYP3A4 inhibitors and P‑gp inhibitors (e.g., certain antifungals or targeted cancer drugs), a clinically significant pharmacokinetic interaction with a drug not listed among these offenders would be unexpected according to the cited mechanisms; nonetheless, the literature also contains warnings and case reports of idiosyncratic or rare problems (for example warfarin INR changes and post‑marketing reports), so vigilance is advised even when a prior interaction hasn’t been catalogued [4] [3] [7].
5. Practical guidance, uncertainty, and the competing narratives
Given the limits of the supplied sources, the prudent stance reflected across the databases is to inform prescribing clinicians and pharmacists about all medications (including tamsulosin), to monitor for clinical signs such as increased dizziness or other new adverse effects after starting ivermectin, and to recognize that interaction checkers are helpful but not exhaustive; some outlets stress many possible interactions to err on the side of caution (Drugs.com, Medscape, Mayo Clinic, WebMD) while pharmacokinetic reviews emphasize mechanistic plausibility — both perspectives cohere around caution, though no source here documents a direct ivermectin–tamsulosin interaction [1] [4] [9] [10] [7].