If Viagra refers to sildenafil, it is recommended that it be taken between 30 minutes and 4 hours before sexual activity for better results. If it is any other drug, it is sufficient to take it within 1 day. Sildenafil is mainly used to treat erectile dysfunction and is usually taken between 30 minutes and 4 hours before sexual activity. Sexual provocation is required for the treatment of erectile dysfunction to be effective. In the case of other drugs that can treat erectile dysfunction, such as tadalafil and vardenafil. Because of their very long half-life, they do not have to be taken strictly half an hour or one hour before sexual activity, but at any time during the day. As long as there is arousal at the time of sexual activity, it remains very effective. Patients in daily life should pay attention to taking Viagra for better efficacy with proper sexual stimulation, such as hugging, kissing, caressing, etc., otherwise there is a risk that the drug will be ineffective. In addition, it is not recommended that middle-aged and elderly people take Viagra for a long time to avoid health effects.