Injection therapy typically uses one or more drugs which must be prescribed by a doctor, usually a urologist. The man directly injects the drugs into the side of his penis when he wishes to have an erection. The drugs tell the blood vessels in the penis to open, and increased blood flow into the penis creates an erection. The erection is exactly the same as a natural erection because the penis is being pumped full with blood, just like during a natural erection.

When men are interested in penile injection therapy, the first trial injection is performed in the urologist's office by the doctor to be sure that the patient has no side effects. If a patient wishes to do injections at home he will come back for a second visit, in which the patient is taught how to do the injections. Patients can then try the medications at home.

Who are good candidates for penile injection therapy?

Penile injection therapy can be a good alternative for the 30-40% of men who fail to get adequate results from oral medications. The best treatment for erectile dysfunction, however, depends on many things. These include a man's health and personal and physical tolerance for the treatment. A man with ED should involve his spouse or partner and his doctor in the treatment decision.

Who are not good candidates for penile injection therapy?

Some conditions rule out the use of injection therapy.

• Allergy to the injected medications.
• Abnormally formed penis.
• Peyronie's disease or penis angulation.
• Carvernosal fibrosis.
• Diseases that might result in prolonged erection, such as sickle cell anemia.
• Men who take Coumadin or other blood thinners

Medications used for injection therapy

The most common drugs are Papavarine, Phentolamine and alprostadil. Most men use alprostadil, which is also known as prostaglandin E. This medication can be pre-mixed, in which case a man simply draws the right amount of medication into a syringe for injection. It can also be purchased in a kit which contains a freeze-dried pellet of medication in a special syringe. The pre-mixed alprostadil is less expensive than the freeze dried kits, but must be kept in a refrigerator or it will lose its strength. The "kits" can be kept at room temperature and are very convenient for men who travel. The most commonly used brand of freeze-dried kit is called Caverject. Patients who do not get an adequate erection with alprostadil, or who have pain after injection, may use a combination of papaverine, phentolamine, and alprostadil called tri-mix. This combination is prepared at specialty pharmacies and shipped to your home.

Risks of injection therapy

Pain

The pain of the needle injection is minimal for most men, but 15% of men will have aching pain in the penis for 30-60 minutes after injection. Sometimes men can change medications to one that does not cause them pain.

Bruising

This is usually minimal and of no consequence.

Prolonged erection (priapism)

This is the most serious side effect and affects less than 5% of men. The men most likely men to have priapism are men with spinal cord injury, men younger than 40, or men who inject more than once in 24 hours. If a man has a fully rigid erection for more than 4 hours it will become painful, and after six hours priapism can damage the blood vessels in the penis. If a patient has a fully rigid erection three hours after injection he should call his doctor or go to the nearest emergency room.

Penile Scarring

Around 5% of men who perform injection therapy will develop scarring inside the penis which may cause bending of the erection.

Infection

It is extremely rare to have infection after penile injection therapy.