Answer
Combining tadalafil with doxazosin is not recommended because studies using doxazosin 4 or 8 mg daily with tadalafil 5 mg daily or 20 mg once showed significantly increased blood-pressure lowering lasting at least 12 hours, potentially causing symptoms including fainting (syncope).
Sources for this answer
- Cialis 2.5mg film-coated tabletsEli Lilly and Company Limited · emc · SmPC §4.5 Interaction with other medicinal products · Version 33Document updated
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