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Caverject Injections: How They Work & Side Effects

Mike Bohl, MD, MPH, ALM

Reviewed by Mike Bohl, MD

Written by Rachel Sacks

Published 11/28/2022

Updated 01/18/2024

Whether you’re single, married, in an open relationship, gay, straight, bi or can’t be defined by labels, the functioning of your penis is probably still pretty high on your list of health priorities.

If erectile dysfunction (ED) is making your high-priority body part function poorly, you may be willing to go to great lengths to make it work. Do those lengths include Caverject® injections?

It’s understandable to think needles shouldn’t be in the same vicinity as your penis, let alone a solution to performance troubles. Truth be told, we were skeptical too.

There are plenty of harmful products for male performance enhancement (we’re looking at you, gas station sex pills and sketchy supplements). So when people start talking about needles, it makes sense to wonder if this is really the best choice.

We’ll go over the evidence about Caverject injection treatment for erectile dysfunction to help you understand how these ED injections work.

Before we dive into the data, let’s get some basics about this treatment out of the way, starting with the most obvious question: Just what is Caverject?

While dealing with ED can be difficult, there are (fortunately) quite a few treatment options, including intracavernosal injections. Believe it or not, injectable penile medications are an effective way to maintain an erection.

Also sold as Caverject Impulse®, Caverject injections consist of a medication called alprostadil, along with inactive ingredients like lactose and sodium citrate. Sometimes referred to as prostaglandin E1 or PGE1, alprostadil is designed to help your blood vessels dilate better.

This is a good thing in the context of ED. How so? Wider blood vessels increase blood flow to the penis, which helps you achieve and maintain an erection sufficient for satisfactory sexual intercourse once you become aroused.

Alprostadil injections are approved by the U.S. Food and Drug Administration (FDA) for the treatment of erectile dysfunction.

Although it’s a minimally invasive solution, these injections are considered a second line of treatment when lifestyle changes or oral medications don’t work. This is simply due to the difficulty of injecting your penis compared to taking a pill.

The point of Caverject is that it delivers the vasodilator medication directly to the site where it’s needed. This allows it to start working pretty quickly.

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While self-injection may seem pretty straightforward, there are a few details about Caverject injections you should know.

Your first injection should be given by a healthcare professional, who’ll then provide you with instructions on how to do the injections yourself, including proper injection technique.

There are a few supplies you’ll need to have on hand, such as:

  • Diluent (bacteriostatic water for injection preserved with benzyl alcohol)

  • A 1-mL (milliliter) to 3-mL syringe, depending on your dosage

  • Alcohol wipes to sterilize the injection site

  • 29-gauge or 30-gauge half-inch needles

Since you’ll use a new needle each time, you may also need a sharps container to safely dispose of them.

Self-Administering Caverject Injections

Using a fresh, sterile needle, wipe the intracavernosal injection site with an alcohol swab. Making sure to avoid veins, use the syringe plunger to administer an effective dose. Retract your foreskin if need be, stretch your penis out, and inject on either the right or left side of the shaft.

You don’t want to go too far in. The point is to enter one of the corpora cavernosa (the two chambers of spongy tissue on either side of the penis that fill with blood to achieve an erection).

Compress the site of injection for five minutes or until any bleeding stops. After that, dispose of the needles in a sharps container, and throw away any unused mixture in the syringe.

Caverject injections use superfine needles to deliver the medicine, which can easily bend or warp. If you notice a bent needle or see needle breakage, don’t use it. Throw the damaged needle out and start with a new one.

Bear in mind these are general guidelines — always follow your healthcare provider’s directions to a T.

But wait — what’s considered an effective dose?

A single dose of Caverject can range anywhere from 2.5 to 40 micrograms (mcg). Single-use vials usually contain 20 or 40 micrograms of alprostadil to be injected no more than three times a week.

Your healthcare provider will make a dosage recommendation based on the cause or severity of your ED.

An erection may occur within five to 20 minutes after injection, lasting 30 minutes to one hour.

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Earlier, we mentioned that Caverject is considered a second-line treatment for erectile dysfunction. That’s partially for convenience (a pill is easier to take than an injection) and partly because typical first-line ED treatments are safer.

Alprostadil is effective in the management of erectile dysfunction. However, it’s by no means a cure and won’t help you return to the spontaneous erectile function or natural erectile function of your youth.

An injection of Caverject might be beneficial for those who shouldn’t use oral ED medications (known as PDE5 inhibitors), prefer not to take pills or find that PDE5 inhibitors are ineffective.

These injections have been found effective in a wide range of men during clinical trials, including generally healthy guys struggling with ED, those with health conditions like diabetes and men with spinal cord injuries.

A 2001 study found that Caverject injections were effective for achieving an erection, specifically for men with diabetes and erectile dysfunction.

The research we have is pretty straightforward: Caverject works. And when administered correctly, you can minimize the risk of side effects.

Of course, no medication is without the possibility of side effects — and Caverject injections are no exception.

Possible side effects of Caverject include:

  • Penile pain

  • Penile fibrosis

  • Injection site hematoma

  • Penile numbness, irritation, sensitivity, pruritus, erythema, skin tear, discoloration, itching

  • Injection site ecchymosis

  • Penile rash

  • Penile edema

In clinical trials, the most common side effect was penile pain. And there’s a small chance of experiencing angulation (an abnormal bend in the penis) or Peyronie’s disease.

Caverject may also increase the risk of a condition called priapism. This is when an erection lasts more than four hours without any obvious source of physical or mental sexual stimulation.

If you have a medical condition that predisposes you to priapism, like multiple myeloma, leukemia or sickle cell anemia, your healthcare provider may recommend a different ED treatment.

If your erection lasts more than four hours or you’re experiencing a painful erection, seek medical attention immediately.

Practically speaking, the reason you may not have heard much about this medication is that there are other, less intrusive, effective medications to improve sexual activity — ones you can just swallow (or chew if you enjoy hard mints).

These PDE5 (phosphodiesterase type -5) inhibitor medications also increase blood flow to the penis but are less invasive.

The most common PDE5 inhibitors include:

Viagra is the one you’ve most likely heard of before. It’s a popular choice, thanks to its relatively low side effects.

While PDE5 drugs are often most effective for physical causes of erectile dysfunction, there’s a chance you’re dealing with psychological ED. The psychological causes of erectile dysfunction include mental health conditions like depression, relationship problems and sexual performance anxiety, among others.

If this is the case, you’re wise to talk to a licensed mental health professional, either in person or through online therapy. They can help you identify what’s causing your stress or anxiety and find ways to manage your mental health.

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Although it’s a prevalent problem affecting many men, you don’t have to live with erectile dysfunction. Plenty of solutions are available, including Caverject injections.

But what is this treatment about? Here’s what to remember:

  • Known as intracavernosal alprostadil and sold under the brand name Caverject, this medication is injected into the penis to help produce an erection relatively quickly.

  • While this treatment is typically well-tolerated, the most common side effect is penile pain. Other possible side effects include prolonged erections lasting more than four hours.

  • While Caverject is not a typical first-line ED treatment (lifestyle changes and oral ED medication are), some men use Caverject as an effective option if first-line treatments aren’t effective or appropriate.

Knowing the possible underlying cause of your sexual dysfunction can help a medical professional figure out the best treatment options for you. Healthcare providers can offer personalized medical advice and will often recommend lifestyle modifications and possible erectile dysfunction medications.

To access medical guidance and ED treatments online, check out our sexual health telehealth platform.

You can also explore penile implants, at-home premature ejaculation techniques and other alternative erectile dysfunction remedies on our blog.

10 Sources

  1. Treatment for Erectile Dysfunction - NIDDK. (n.d.). National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved from
  2. Jain, A., Iqbal, O.A. Alprostadil. [Updated 2023 Jul 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Retrieved from
  3. Yafi, F. A., Jenkins, L., Albersen, M., Corona, G., Isidori, A. M., Goldfarb, S., Maggi, M., Nelson, C. J., Parish, S., Salonia, A., Tan, R., Mulhall, J. P., & Hellstrom, W. J. (2016). Erectile dysfunction. Nature reviews. Disease primers, 2, 16003. Retrieved from
  4. Alprostadil Urogenital. (2023, February 15). MedlinePlus. Retrieved from
  5. CAVERJECT ® (alprostadil) for injection, for intracavernosal use. (2017, November 6). Retrieved from
  6. Burnett, A. L., Nehra, A., Breau, R. H., Culkin, D. J., Faraday, M. M., Hakim, L. S., Heidelbaugh, J., Khera, M., McVary, K. T., Miner, M. M., Nelson, C. J., Sadeghi-Nejad, H., Seftel, A. D., & Shindel, A. W. (2018). Erectile Dysfunction: AUA Guideline. The Journal of Urology, 200(3), 633-641. Retrieved from
  7. Heaton, J. P., Lording, D., Liu, S. N., Litonjua, A. D., Guangwei, L., Kim, S. C., Kim, J. J., Zhi-Zhou, S., Israr, D., Niazi, D., Rajatanavin, R., Suyono, S., Benard, F., Casey, R., Brock, G., & Belanger, A. (2001). Intracavernosal alprostadil is effective for the treatment of erectile dysfunction in diabetic men. International journal of impotence research, 13(6), 317–321. Retrieved from
  8. Huang, S. A., & Lie, J. D. (2013). Phosphodiesterase-5 (PDE5) Inhibitors In the Management of Erectile Dysfunction. P & T : a peer-reviewed journal for formulary management, 38(7), 407–419. Retrieved from
  9. Label: VIAGRA (sildenafil citrate) tablets. (n.d.). Retrieved from
  10. U.S. Food and Drug Administration (FDA). (2021). Sharps Disposal Containers. Retrieved from
Editorial Standards

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. See a mistake? Let us know at [email protected]!

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Mike Bohl, MD

Dr. Mike Bohl is a licensed physician, a Medical Advisor at Hims & Hers, and the Director of Scientific & Medical Content at a stealth biotech startup, where he is involved in pharmaceutical drug development. Prior to joining Hims & Hers, Dr. Bohl spent several years working in digital health, focusing on patient education. He has also worked in medical journalism for The Dr. Oz Show (receiving recognition for contributions from the National Academy of Television Arts and Sciences when the show won Outstanding Informative Talk Show at the 2016–2017 Daytime Emmy® Awards) and at Sharecare. He is a Medical Expert Board Member at Eat This, Not That! and a Board Member at International Veterinary Outreach.

Dr. Bohl obtained his Bachelor of Arts and Doctor of Medicine from Brown University, his Master of Public Health from Columbia University, and his Master of Liberal Arts in Extension Studies—Journalism from Harvard University. He is currently pursuing a Master of Business Administration and Master of Science in Healthcare Leadership at Cornell University. Dr. Bohl trained in internal medicine with a focus on community health at NYU Langone Health.

Dr. Bohl is Certified in Public Health by the National Board of Public Health Examiners, Medical Writer Certified by the American Medical Writers Association, a certified Editor in the Life Sciences by the Board of Editors in the Life Sciences, a Certified Personal Trainer and Certified Nutrition Coach by the National Academy of Sports Medicine, and a Board Certified Medical Affairs Specialist by the Accreditation Council for Medical Affairs. He has graduate certificates in Digital Storytelling and Marketing Management & Digital Strategy from Harvard Extension School and certificates in Business Law and Corporate Governance from Cornell Law School.

In addition to his written work, Dr. Bohl has experience creating medical segments for radio and producing patient education videos. He has also spent time conducting orthopedic and biomaterial research at Case Western Reserve University and University Hospitals of Cleveland and practicing clinically as a general practitioner on international medical aid projects with Medical Ministry International.

Dr. Bohl lives in Manhattan and enjoys biking, resistance training, sailing, scuba diving, skiing, tennis, and traveling. You can find Dr. Bohl on LinkedIn for more information.


  • Younesi, M., Knapik, D. M., Cumsky, J., Donmez, B. O., He, P., Islam, A., Learn, G., McClellan, P., Bohl, M., Gillespie, R. J., & Akkus, O. (2017). Effects of PDGF-BB delivery from heparinized collagen sutures on the healing of lacerated chicken flexor tendon in vivo. Acta biomaterialia, 63, 200–209.

  • Gebhart, J. J., Weinberg, D. S., Bohl, M. S., & Liu, R. W. (2016). Relationship between pelvic incidence and osteoarthritis of the hip. Bone & joint research, 5(2), 66–72.

  • Gebhart, J. J., Bohl, M. S., Weinberg, D. S., Cooperman, D. R., & Liu, R. W. (2015). Pelvic Incidence and Acetabular Version in Slipped Capital Femoral Epiphysis. Journal of pediatric orthopedics, 35(6), 565–570.

  • Islam, A., Bohl, M. S., Tsai, A. G., Younesi, M., Gillespie, R., & Akkus, O. (2015). Biomechanical evaluation of a novel suturing scheme for grafting load-bearing collagen scaffolds for rotator cuff repair. Clinical biomechanics (Bristol, Avon), 30(7), 669–675.

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