Doxazosin and Terazosin interaction
Doxazosin and Terazosin: 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 Doxazosin (Doxazosin mesylate) label · effective 2025-11-24
The use of Doxazosin tablet is contraindicated in patients with a hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or any of its components.
As with other alpha-blockers, there is a potential for syncope, especially after the initial dose or after an increase in dosage strength.
From the Terazosin (TEZRULY) label · effective 2025-04-18
Risk of Hypotension with Concomitant Use of Other Antihypertensive Agents and Phospodiesterase Type 5 Inhibitors (PDE5-I): Concomitant administration of TEZRULY with antihypertensives or phosphodiesterase-5 (PDE-5) inhibitors can result in additive blood pressure lowering effects and symptomatic hypotension (5.3).
Syncope has also been reported with other alpha-1-adrenoceptors antagonists in association with rapid dosage increases or the introduction of another antihypertensive drug.
Then slowly increase the dose [see Dosage and Administration (2.1 and 2.2)] , and add additional antihypertensive agents with caution.
Risk of Hypotension with Concomitant Use of Other Antihypertensive Agents and Phosphodiesterase Type 5 Inhibitors (PDE5-I) Concomitant use of TEZRULY with other anti-hypertensive agents, especially the calcium channel blocker verapamil, can increase the risk of 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.