Several different medications can help produce an erection when injected into the penis. These medicines relax the erectile tissue so that blood flows into the penis. As pressure builds, the small veins are shut off and the erection becomes firm. The dose of medicine should ideally create a firm erection lasting for 45 to 60 minutes. 

How Do Penile Injections Work?

• You inject the medication into your penis about 20 to 30 minutes before you want to have a firm erection. 

Good to Know

You can fill in that time with touching or foreplay, so by the time you are ready for penetration, you have a firm erection. 

• The injection is done around the middle of the shaft of the penis, not on the sensitive head (glans). 

• These drugs help open the blood vessels to allow more blood to flow into the penis, as well as relaxing the tissue inside the penis.  

• After injecting the medicine into the penis, a man should press the area between his thumb and forefinger for about three minutes (or up to five minutes for men who take blood-thinning medications). 

• The goal is to get an erection firm enough to enjoy sexual activity. For most men, that means about 60% to 80% firm, lasting for 45 to 60 minutes. 

• Some men with premature ejaculation say that injection therapy helps them delay their climax. In general, however, injection therapy does not change sensation on the skin of the penis or affect a man’s ability to reach orgasm, ejaculate semen, or urinate. 

What are the Common Side Effects?

• Aching and/or burning sensation in the penis (often described as “pins and needles”). This is typical when using prostaglandin E1 medications. Men who have discomfort with prostaglandin E1 can often avoid pain by using Trimix, which contains a much lower dose of prostaglandin E1, or Bimix which eliminates it altogether. 

• Bleeding at the injection site. This can be minimized by compressing the injection site properly. 

• Bruising at the injection site 

• Redness or swelling at the injection site 

• Allergic rash 

• Dizziness after injecting 

• Priapsim, or a firm erection that lasts for more than four hours and is considered a medical emergency. 

Good to Know

Injection therapy can cause scarring in penile tissue. If you notice any lumps, curvature, or changes to the skin, please talk with your medical team. 

What Questions Should I Ask My Provider? 

• What should I do if my erection does not go down? 

• How long will I need to use the injections for? 

• What should I do if the injection does not produce an erection? 

• How often can I use injection therapy for erections?  

Always follow the instructions given to you by your provider. Do not make adjustments on your own.