What side effects can this medication cause? Continue to take sildenafil even if you feel well. Do not stop taking sildenafil without talking to your doctor. The mechanism of action for ED pills is simple: They inhibit the PDE5 enzyme which regulates the signals responsible for the smooth muscle tissue. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand.Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung . 1. How it works Sildenafil may be used to treat erectile dysfunction (ED or impotence) in men (Viagra brand) or pulmonary arterial hypertension in both men and women (Revatio . Medications Prescribed: Viagra, Cialis, sildenafil, tadalafil Generic offered: Yes Why We Chose It.