By controlling the enzyme phosphodiesterase, sildenafil helps to maintain an erection that is produced when the penis is stroked. Without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection.

How to use : Taken by mouth as needed between four hours and one-half hour before sexual activity (about one hour before is most effective). Take only as directed, usually once daily as needed. Sildenafil works along with sexual stimulation to help achieve an erection.

Before Using This Medicine :

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. For sildenafil, the following should be considered:

• Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to sildenafil. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.
• Pregnancy—Sildenafil is not indicated for use in women. Sildenafil has not been studied in pregnant women. However, sildenafil has not been shown to cause birth defects or other problems in animal studies.
• Breast feeding—It is not known whether sildenafil passes into breast milk. Sildenafil is not indicated for use in women.
• Older adults—Elderly people are especially sensitive to the effects of sildenafil, which may increase their chance of having side effects. Patients 65 years of age and older are started on a low dose, 25 mg, of sildenafil. The dose may be increased by a doctor as needed and tolerated.
• Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking sildenafil, it is especially important that your health care professional know if you are taking any medications.