Viagra generally refers to sildenafil citrate, it is strictly prohibited to combine the drug with nitrate drugs when taking the drug, it is prudent to use the drug for those who have low blood pressure, refractory high blood pressure, stroke, liver and kidney diseases, etc. Do not drink alcohol before or after taking the drug. 1. It is strictly prohibited to use with nitrate drugs at the same time, including nitroglycerin, isosorbide nitrate tablets, etc. Otherwise, the blood pressure will fall sharply, and even cause sudden death. 2. It is forbidden to take it if you have low blood pressure, refractory arrhythmia, refractory hypertension, have had a stroke in the last 6 months, or are taking α-blockers. 3. People with heart problems, kidney or liver disease, sickle cell anemia, leukemia, and those who are allergic to the ingredients of this drug should consult a doctor before deciding whether to use the drug. 4. You should not drink alcohol before or after taking the medicine. Sildenafil citrate is used as prescribed by the doctor when taking medication, and specific contraindications can also be found by consulting a doctor.