Viagra refers to sildenafil, usually the first time to take need to pay attention to the indications, contraindications and other aspects. 1. Indications: Sildenafil belongs to type 5 phosphodiesterase inhibitors, which are mainly used for the treatment of erectile dysfunction in the clinic, with the effect of vasodilatation, which can effectively alleviate the sexual function of patients. 2. Contraindications: It is forbidden to combine with nitrate drugs, and this drug is forbidden for women, people who are allergic to this product, children, and people who are not suitable for sex in recent cardiovascular status. 3.Other: In addition, patients taking sildenafil will only work when there is sexual stimulation. Secondly, some patients may experience dizziness, visual abnormalities and other discomforts after taking this drug, so driving is not recommended after using the drug. All in all, patients must take Sildenafil under the guidance of a doctor, do not self-medicate and adjust the dosage.