Editing Sildenafil (section)

=== Interactions ===
Care should be exercised by people who are also taking [[Protease inhibitor (pharmacology)|protease inhibitors]] for the treatment of [[HIV/AIDS|HIV infection]]. Protease inhibitors inhibit the metabolism of sildenafil, effectively multiplying the plasma levels of sildenafil, increasing the incidence and severity of side effects. Those using protease inhibitors are recommended to limit their use of sildenafil to no more than one 25&nbsp;mg dose every 48 hours.<ref name="Viagra FDA label" /> Other drugs that interfere with the metabolism of sildenafil include [[erythromycin]] and [[cimetidine]], both of which can also lead to prolonged plasma half-life levels.<ref>{{cite journal | vauthors = Schwartz BG, Kloner RA | title = Drug interactions with phosphodiesterase-5 inhibitors used for the treatment of erectile dysfunction or pulmonary hypertension | journal = Circulation | volume = 122 | issue = 1 | pages = 88–95 | date = July 2010 | pmid = 20606131 | doi = 10.1161/CIRCULATIONAHA.110.944603 | s2cid = 13207143 | doi-access = free }}</ref>

The use of sildenafil and an [[Alpha-1 blocker|α<sub>1</sub> blocker]] (typically prescribed for [[hypertension]] or for urologic conditions, such as [[benign prostatic hypertrophy]]) at the same time may lead to low blood pressure, but this effect does not occur if they are taken at least 4 hours apart.<ref name="Kloner">{{cite journal | vauthors = Kloner RA | title = Pharmacology and drug interaction effects of the phosphodiesterase 5 inhibitors: focus on alpha-blocker interactions | journal = The American Journal of Cardiology | volume = 96 | issue = 12B | pages = 42M–46M | date = December 2005 | pmid = 16387566 | doi = 10.1016/j.amjcard.2005.07.011 }}</ref>