Sildenafil is particularly effective the first time you take it probably because the drug’s efficacy is well defined, plus the person using the drug may be sensitive to it. Sildenafil is mainly used to treat erectile dysfunction in men. The clinical efficacy of this product is relatively clear, and some people may be more sensitive to the drug, so that it produces a stronger effect after taking it. If the effect of this medication is too strong or discomfort occurs, the next dose can be appropriately reduced, which can reduce the incidence of adverse reactions. Adverse reactions that often occur after taking sildenafil include myalgia, nasal congestion, abnormal vision, rash, dizziness, nausea, flushing, etc. It is contraindicated for those who are allergic to the product and those who are taking nitrate drugs, children, women and other people. It is recommended to use the drug under the guidance of a physician and adjust the dosage appropriately according to their own reactions to avoid adverse reactions.