Viagra is used to treat erectile dysfunction in men. You can buy Viagra online, it relaxes the muscles of the walls of blood vessels and increases blood flow to particular body areas. It usually takes only 30 minutes to 1 hour before sexual activity. Don’t take Viagra more than once per day. Viagra is available in multiple dosages, like 25 mg, 50 mg, and 100 mg tablets. The starting dose of Viagra is 50 mg, Viagra can not cure erectile dysfunction. It is just a treatment for erectile dysfunction.