Men with weak erections are recommended to take PDE5 inhibitors, such as sildenafil, tadalafil, etc. Erectile dysfunction is usually caused by erectile dysfunction, and this kind of medication has a certain effect on the treatment of erectile dysfunction. 1. Sildenafil: Sildenafil is a short-acting drug, usually taken one hour before sex, the effect of the drug can be maintained for about 4 hours, during the period of consumption can not drink alcohol, in addition, some patients may be after taking some adverse reactions, such as dizziness, headache, flushing, blurred vision and so on. 2. Tadalafil: tadalafil can be taken after the efficacy of the drug can be maintained in 72 hours or so, such drugs are not affected by food, but some patients may appear after taking headache, back pain, nasopharyngitis and other adverse reactions, in addition to suffering from cardiovascular disease patients can not take. It is worth noting that both sildenafil and tadalafil are prescription drugs, so they need to be used under the guidance of a doctor, and buying and taking them privately may cause harm to the body, and secondly, they can not be taken with any nitrate drugs, which may be life-threatening.