In case of erectile dysfunction or lack of hardness, the medication can be treated with phosphodiesterase type 5 inhibitors, which can make the penis hard. Commonly used drugs for type 5 phosphodiesterase inhibitors are sildenafil, vardenafil, tadalafil and so on. This kind of drug can inhibit the type 5 phosphodiesterase that breaks down the cyclic guanosine in the cavernous body to enhance the effect of nitric oxide. When sexual stimulation causes local nitric oxide release, sildenafil inhibits the type 5 phosphodiesterase, which can increase the level of cyclic guanosine in the cavernous body, relaxes the smooth muscle, and the blood flows into the cavernous body, and it can promote the erection of the penis to make the penis hard under the sexual stimulation. Type 5 phosphodiesterase inhibitor adverse reactions are abdominal pain, nausea, dizziness, headache, increased heart rate, myocardial ischemia, rash, etc.; Contraindications include, allergic to the drug is prohibited, the use of nitrate drugs during the use of nitrate drugs is prohibited, there is a risk of inducing heart disease, there are patients with heart disease to be cautious about using. There are abnormalities in sexual function, it is recommended to first go to the hospital to clarify the cause, and follow the doctor’s instructions for treatment.