Viagra is the trade name, generic name of sildenafil citrate tablets, the first use of this drug on taking 100mg is not necessarily dangerous, and with the physical condition of the user, tolerance and other factors, the specific circumstances vary from person to person. Sildenafil citrate tablets for the first use of the recommended dose of 50mg, after the efficacy and tolerance can be adjusted according to the dose range of 25 to 100mg, the first time the drug 100mg has reached the maximum recommended dose, but whether there is a danger patient situation. 1. The possibility of risk is small: if the patient is young, the basic condition is good, the drug is well tolerated, and not taking drugs that may increase the plasma level of the drug (such as erythromycin and other strong inhibitors of cytochrome P4503A4), then even if the dose of 100mg will not occur adverse events. 2. If the patient is >65 years of age, has a poor baseline condition (especially in combination with hepatic or renal impairment), is sensitive to or poorly tolerates the drug, and is using a drug that increases plasma levels of sildenafil as described above, there is a high likelihood that an adverse event will occur with a dose of 100mg. It should also be noted that sildenafil citrate tablets are contraindicated in people who are allergic to them or who are using nitrate drugs (such as isosorbide mononitrate), guanylate cyclase agonists (such as linaclotide), and that there is a possibility of headache, visual abnormalities and other adverse reactions during the course of the medication. To sum up, those who have the need to use sildenafil citrate tablets must standardize and rationalize the use of medication under the guidance of a doctor, do not blindly take medication or increase or decrease the dosage of medication on their own, so as not to cause adverse consequences.