These medicines all work well for ED. Dose adjustments due to interactions for sildenafil When used for Erectile dysfunction Manufacturer advises a starting dose of 25 mg with concurrent use of moderate and potent inhibitors of CYP3A4. Manufacturer advises reduce dose to 20 mg once daily with concurrent use of some potent inhibitors of CYP3A4 avoid with ketoconazole, itraconazole and ritonavir. Pulmonary arterial hypertension initiated under specialist supervision for sildenafil By mouth 20 mg 3 times a day. The most common symptoms of erectile dysfunction include difficulty achieving or maintaining an erection and reduced sexual desire. There are no antidotes available for sildenafil.Find patient medical information for sildenafil oral on MD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. SHOP NOW AT HIMS. Healthline ‘s review. Similar to Viagra and sildenafil, Cialis is a PDE5 inhibitor and works by improving blood flow to the penis and reducing ED symptoms. Hims offers. Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when you get sexually excited.