How Does Alprostadil Treat Erectile Dysfunction?

Medically Reviewed by Nazia Q Bandukwala, DO on February 17, 2024
Written by WebMD Editorial Contributors
4 min read

Alprostadil is a medicine that men take for ED (erectile dysfunction). It’s only available by prescription.

This drug makes the blood vessels expand. That boosts blood flow throughout the body, including the penis, so it helps men with ED have an erection.

You can get alprostadil injected directly into the penis. Or you can use it as a suppository, placing it into the opening at the tip of the penis.

Injectable alprostadil is sold under the brand names Caverject, Edex, and Prostin VR. The suppository form is called “MUSE” (which stands for Medicated Urethral System for Erection).

Alprostadil should only be used in men with erectile dysfunction. If it’s not used properly, it can permanently damage the penis.

The injectable form causes an erection firm enough for sex in more than 80% of men with erectile dysfunction regardless of their age or the cause of their ED.

The suppository form is not as effective. It produces an erection in about 30%-40% of men with ED.

It usually starts to work in about 5 to 20 minutes. Wait 10-30 minutes before you have sex. Your erection should last for about an hour and may continue after you ejaculate.

Don’t use it more than three times a week. Wait at least 24 hours between each use.

This drug is not right for everyone. Before you take it, tell your doctor:

  • If you have ever had an allergic reaction to alprostadil.
  • If you are allergic to any other substances such as drugs, foods, preservatives, or dyes
  • If you take any prescription or over-the-counter drugs including herbal and dietary supplements
  • If you have a penile implant
  • If you have a history of priapism (a painful and prolonged erection not linked to sexual stimulation)

Also, tell your doctor if you have any medical problems, especially:

  • Problems with your penis, such as curvature or birth defects
  • Bleeding problems
  • Penile infection
  • Red or itchy penis
  • Conditions that cause thickened or slower blood flow such as leukemia (cancer of the blood), sickle cell disease or trait, or thrombocythemia (high number of platelets)
  • If you take a blood thinner or you bruise or bleed easily
  • Peyronie's disease

If you can’t take this medicine, your doctor can recommend other treatments.

Your doctor will teach you how to give yourself the injection. If you need to prepare the mixture you’ll inject, follow the directions provided.

Before you draw the medicine into the syringe, wash your hands with soap and water. Set the bottles on a clean surface. Wipe the tops of the injection bottles with an alcohol swab.

After you mix a single dose, you must use it immediately. Throw away any unused mixture in the syringe. Don’t store it -- you cannot use it later on.

Throw out the needles. Do not reuse them!

If you have any questions about how to use this medication, ask your doctor or pharmacist.

First, urinate. The small amount of urine left in the urethra will help dissolve the suppository.

The suppository is about half the size of a grain of rice. You’ll insert it into the urethra (the opening at the end of the penis) using a plastic applicator.

You can use a small amount of lubricant like KY Jelly or Astroglide to help you insert the applicator. Push the button on the applicator to deliver the suppository into the urethra.

To help dissolve the suppository once inside, roll your penis between your hands for 10 seconds. If you feel any stinging, continue this motion to help that feeling stop.

Sit, stand, or walk for 10 minutes to boost blood flow to your penis to help with an erection.

If you have questions, ask your doctor or pharmacist.

Choosing between the injection and suppository is a personal choice. Talk to your doctor about the pros and cons. For example, the injection may be more painful, but it’s more effective than the suppository.

If you use alprostadil (either by injection or suppository) and have sex with a pregnant woman, use a condom. Doctors don’t know if alprostadil will affect the baby.

Store the drug in its original container, out of the reach of children. Follow the directions on the label about where it’s OK to store it. For instance, keep it out of warm, moist settings (such as the bathroom). If you keep it in your fridge, don’t let it freeze.

The most common side effect is pain in the area where you get the shot.

Call your doctor immediately if you have any of these rarer problems:

  • Curving of the penis with pain during an erection
  • Erection lasts for 4 to 6 hours with severe and continuing pain in the penis
  • Swelling or pain in the testes
  • Bleeding or spotting from the urethra
  • Stinging in the urethra