Doxazosin and Tadalafil interaction
Doxazosin and Tadalafil: both prescribing labels 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 Tadalafil (Cialis) label · effective 2026-06-03
…coadministration of an alpha-blocker and CIALIS for the treatment of BPH has not been adequately studied, and due to the potential vasodilatory effects of combined use resulting in blood pressure lowering, the combination of CIALIS and alpha-blockers is not recommended for the treatment of BPH. [see Dosage and Administration ( 2.7 ), Drug Interactions ( 7.1 ),…
Clinical pharmacology studies have been conducted with coadministration of tadalafil with doxazosin, tamsulosin or alfuzosin. [see Dosage and Administration ( 2.7 ), Warnings and Precautions ( 5.6 ), and Clinical Pharmacology ( 12.2 )] .
Use of CIALIS with alpha-blockers, antihypertensives or substantial amounts of alcohol (≥5 units) may lead to hypotension ( 5.6 , 5.9 ).
CIALIS is not recommended in combination with alpha-blockers for the treatment of BPH because efficacy of the combination has not been adequately studied and because of the risk of blood pressure lowering.
Caution is advised when CIALIS is used as a treatment for ED in men taking alpha-blockers.
From the Doxazosin (Doxazosin mesylate) label · effective 2025-11-24
Concomitant administration of Doxazosin with a PDE-5 inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.
Concomitant administration of Doxazosin with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.
Phosphodiesterase-5 (PDE-5) Inhibitors Concomitant administration of Doxazosin with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.
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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.