Sildenafil should not be taken again 12 hours apart. Sildenafil can be used to treat penile erectile dysfunction disorders and is taken up to once a day. It is recommended that patients should take the medication 24 hours apart and not take it again 12 hours apart to avoid adverse reactions such as hearing loss, dizziness as well as tinnitus caused by excessive drug intake. It should be noted that the drug is prohibited for allergic people and people taking nitrate drugs. Patients with erectile dysfunction should take the drug one hour before sexual activity, and try to avoid eating foods with too much fat content during the medication to prevent the drug from affecting its onset of action. Taking sildenafil does not usually work in the absence of sexual stimulation. Patients should take sildenafil treatment correctly under the guidance of a doctor, which can effectively reduce the adverse effects of the drug on the body.