Zenegra 100 Mg is generally associated with sildenafil, a phosphodiesterase type 5 (PDE5) inhibitor used to treat erectile dysfunction (ED). Because formulations can differ between manufacturers and markets, check the packaging to confirm the active ingredient and strength before use. Sildenafil must not be taken with nitrate medicines because the combination can cause a potentially dangerous drop in blood pressure. Sildenafil should also not be used with guanylate cyclase stimulators such as riociguat. Certain alpha-blockers and blood-pressure medicines may require additional medical supervision.