You can drink alcohol three days after taking sildenafil. Sildenafil has a vasodilating effect and can be used to treat erectile dysfunction disorders in men. Usually, it needs to be taken on demand one hour before sexual activity occurs. The drug takes effect after 30 minutes of oral intake, lasts for about four hours, and is usually metabolized within 48 hours. Patients are advised to drink alcohol after three days to prevent the drug and alcohol from reacting and causing irritation to the body. After patients overdose sildenafil, they should go to the hospital in time and delay drinking alcohol appropriately to prevent damage to the body. It is forbidden to take it if you are allergic to this drug, have a stroke, or are using nitrate drugs. Adverse reactions of this drug mainly include headache, flushing, dizziness, nasal congestion, indigestion, visual abnormalities, etc. The drug should be used under the guidance of a doctor.