Taking tadalafil for impotence is effective and does have the potential to fail when the drug is discontinued, this medication improves erectile function in up to 36 hours. The use of tadalafil can be categorized into as-needed and once-daily dosing, as-needed tadalafil tablets can improve erectile function in up to 36 hours, in healthy subjects oral tadalafil average clearance of 2.5L/hour, the average half-life of 17.5 hours, generally lose efficacy after the drug is completely metabolized. However, it should be noted that the product has certain side effects, patients may have headache, nasopharyngitis, back pain, dyspepsia and other clinical manifestations, for the product allergy, taking guanylate cyclase stimulant (such as levocetirizine, etc.), nitrates (such as nitroglycerin tablets, etc.) patients are not allowed to use this product. All of the above medications should be used under the guidance of a doctor, avoid self-medication.