Viagra is generally referred to as sildenafil citrate tablets, and it is contraindicated for pregnant women, children, lactating women, etc., and is used with caution in patients with shock, high blood pressure, and retinitis pigmentosa. Sildenafil citrate tablets can be mainly used to treat erectile dysfunction, but the drug is contraindicated for pregnant women, children and lactating women, as well as those who are taking nitrate drugs. The drug should also be used with caution in patients who are in shock, have had a myocardial infarction in the last 6 months, are hypertensive, have resting state hypotension and have retinitis pigmentosa. At the same time, the occurrence of life-threatening arrhythmias, heart failure, coronary heart disease unstable angina and sickle cell anemia or related anemia patients also need to be careful with the use of the drug, mainly due to the lack of clinical safety and efficacy of the use of the drug in this group of patients. Patients are advised to use the drug in accordance with medical advice.