Alcohol and sildenafil both have vasodilating effects, so it is not recommended to take sildenafil after drinking, and adverse reactions such as hypotension may occur. Sildenafil is able to diastole not only the smooth muscles of the corpus cavernosum but also those of other parts of the body, and is able to mildly lower blood pressure, so it should not be combined with other substances that lower blood pressure. Alcohol, which also dilates blood vessels, increases the incidence of adverse reactions when combined with sildenafil, and should not be taken until at least 24 hours after drinking to avoid adverse effects. Adverse reactions after using sildenafil include flushing, dyspepsia, nausea, back pain, visual abnormalities, myalgia, headache, etc. It is contraindicated for those who are allergic to sildenafil and should not be combined with nitrates. It is recommended to consult a physician before using the drug, and should not be used after drinking.