Viagra generally refers to sildenafil tablets, not anesthetic, belongs to the type 5 phosphodiesterase inhibitors. Sildenafil is mainly used for the treatment of erectile dysfunction, can inhibit the seashore body decomposition of cyclic guanosine phosphate 5-phosphodiesterase, enhance the role of nitric oxide, which leads to the cavernous smooth muscle relaxation of blood flow into the corpus cavernosum, through sexual stimulation to achieve the purpose of penile erection. It does not work through local anesthesia, so it is not a numbing agent. Common adverse reactions to the drug are headache, dizziness, increased heart rate, nausea, vomiting and so on. It is contraindicated in people who are allergic to the drug and in patients taking nitrates. There is also a potential cardiac risk and should be used with caution in patients with heart disease. There is a need for medication should first go to the hospital for examination, under the guidance of the doctor to use drugs, to avoid their own abuse of drugs.