Cimetidine and Tamsulosin interaction
Cimetidine and Tamsulosin: the Tamsulosin prescribing label 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 Tamsulosin (Tamsulosin Hydrochloride) label · effective 2026-08-12
Tamsulosin hydrochloride capsules should be used with caution in combination with cimetidine, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg) [see Drug Interactions ( 7.1 ) and Clinical Pharmacology ( 12.3 )] Tamsulosin hydrochloride capsules should not be used in combination with other alpha adrenergic blocking agents [see Drug Interactions ( 7.2 )…
• Should not be used in combination with strong inhibitors of CYP3A4.
Tamsulosin hydrochloride capsules, 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Drug Interactions ( 7.1 ) and Clinical Pharmacology ( 12.3 )] .
• Tamsulosin hydrochloride capsules, 0.4 mg should not be used with strong inhibitors of CYP3A4 (e.g., ketoconazole).
…significant increase in tamsulosin exposure exists when tamsulosin hydrochloride capsules, 0.4 mg is coadministered with strong CYP3A4 inhibitors in CYP2D6 PMs, tamsulosin hydrochloride capsules, 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Warnings and Precautions ( 5.2 ) and Clinical Pharmacology ( 12.3 )] .
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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.