Read about viagra: "You react to this medicine. Men and see what it will and won't do. Sometimes men suffer from erectile dysfunction. Once was linked solely to emotional causes or a natural decline in sexual energy due to aging. Viagra works by blocking the natural causes for a man to attain and maintain a penile erection sufficient for sexual performance. Good male sexual health. For almost two hours of good hard sex. Viagra works by helping the blood flow out of the penis. Erectile dysfunction varies in severity some men have a total inability to achieve or maintain a strong erection that would be enough for sexual satisfaction of both the partners."