Usually there is no drug that can quickly promote penile erection. People who have difficulty in penile erection can usually be treated with drugs such as sildenafil, tadalafil, vardenafil, etc., but it takes time for their effects to take effect, and they cannot get an erection quickly. Difficulty in penile erection may be the existence of erectile dysfunction, at this time can be applied under the guidance of the doctor sildenafil, tadalafil, vardenafil and other drugs treatment. However, it takes a certain amount of time for this type of medication to work after taking it, and there must be sexual stimulation for it to work. Their onset of action ranges from 20 minutes to 2 hours, depending on factors such as the medication taken and the individual’s constitution. It is important to note that taking this class of drugs may cause adverse reactions such as headaches, back pain, and indigestion. It is contraindicated for people who are allergic to any of the ingredients in this class of drugs, patients who are taking any form of nitrates, guanylate cyclase stimulators, women, children and other people. It is recommended that patients under the guidance of a doctor strict medication, not blindly use drugs, in addition to medication patients can also be through physical exercise to enhance physical fitness, improve sexual function, usually to quit smoking and alcohol.