Tadalafil is clinically used for the treatment of erectile dysfunction and pulmonary hypertension in men, and certain adverse reactions may occur during use, such as headache, nausea, facial flushing, visual disturbances and so on. Tadalafil can diastole the smooth muscle of the penile corpus cavernosum and promote the increase of blood flow to the penile corpus cavernosum, which can improve the hardness of erection under the effect of sexual stimulation. Common adverse reactions include headache, dyspepsia, nausea, facial flushing, nasal congestion, and visual disturbances. Tadalafil is contraindicated in people who are allergic to any of the ingredients in the product, patients who are taking any form of nitrates, guanylate cyclase stimulators, women, children and other people. Tadalafil needs to be taken under the guidance of a doctor who chooses a reasonable dosage. In case of drug overdose or more serious side effects, such as allergy, low blood pressure, hemorrhage, visual disturbances, abnormal penile erection, etc., it is necessary to go to the hospital in time.