The purple pill viagra is prescribed to males who have erectile dysfunction. Sildenafil Citrate, a component in this medication, helps men's penis tissues receive more blood flow, enabling you to have longer sex sessions with your partner. Men alone, over the age of 18, may use this medication. This medication can be used either before or after food. This medication takes five hours to take effect. Take this medication half an hour before sexual activity. Follow your doctor's advice when taking this medication. Don't use this medication often. Follow your doctor's advice when taking this medication.