Prazosin and Tamsulosin interaction
Prazosin 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
• Should not be used in combination with other alpha adrenergic blocking agents ( 5.2 , 7.2 , 12.3 )
…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 ) and Clinical Pharmacology ( 12.3 )] .
As with other alpha adrenergic blocking agents there is a potential risk of syncope [see Adverse Reactions ( 6.1 )] .
Other Alpha Adrenergic Blocking Agents The pharmacokinetic and pharmacodynamic interactions between tamsulosin hydrochloride capsules and other alpha adrenergic blocking agents have not been determined; however, interactions between tamsulosin hydrochloride capsules and other alpha adrenergic blocking agents may be expected [see Warnings and Precautions ( 5.2…
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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.