Treating Priapism: A Prolonged, Painful Erection

January 3, 2024
A man holding an ice bag to a painful erection

Priapism is defined as a prolonged, painful erection that is unrelated to sexual stimulation or lasts well beyond when stimulation has ended. Ejaculation does not relieve priapism. The length of erection time used to define priapism varies between studies, but most studies and the American Urological Association define priapism as an erection lasting 4 hours or more.

Priapism affects between 0.73 and 5 out of every 100,000 adult men in the United States annually.1,2 About one-fourth of cases of priapism are caused by intracavernosal penile injections and phosphodiesterase 5 inhibitors (PDE5), which are used to treat erectile dysfunction (ED). 3 Priapism is uncommon when standard doses of PDE5 inhibitors are used but occurs in 0 to 35% of men who take intracavernosal injections.4 The incidence of priapism with Trimix ranges from 0% to 3.7% of users.5

Priapism is a genitourinary emergency. If left untreated, permanent damage to the penis may occur. About 5% of emergency visits in the U.S. are related to the genitourinary system, with priapism being one of the most serious.6

What is priapism?

Priapism is a persistent penile erection that is not in response to sexual stimulation and does not resolve with ejaculation. There are three main types of priapism:

Ischemic priapism

Ischemic priapism is the most common cause of prolonged, painful erections. It accounts for about 95% of cases. Ischemic priapism must be treated within 4 to 6 hours to minimize the risk of damage to the penis and complications, such as impotence or erectile dysfunction.6

Ischemic priapism is also known as low-flow priapism. The shaft of the penis will be rigid, the glans remains soft, and pain usually gets progressively worse.

Non-ischemic priapism

Also known as high-flow priapism, non-ischemic priapism occurs when blood is continually pumped into an already engorged penis. The most common cause of non-ischemic priapism is an injury to the perineum (the space between the genitals and the anus) or an abnormal connection between blood vessels.

Non-ischemic priapism is generally not painful. Up to 62% of non-ischemic priapism events resolve spontaneously without treatment.7

Recurrent ischemic priapism

Recurrent ischemic priapism, also known as stuttering priapism, is a less common form of ischemic priapism. Recurrent episodes of ischemic priapism are most commonly found in men with sickle cell disease.

Though all three types of priapism need evaluation, this article will focus on the most common type of priapism—ischemic priapism.

What causes priapism?

Penile erections occur when the smooth muscle lining the cavities in the penis (corpora cavernosa) relaxes and begins to fill with arterial blood. As pressure increases, small veins draining the penis are compressed. This causes blood to be trapped in the penis, which causes it to stiffen.

Nitric oxide is a gas that is released from nerve endings near the small blood vessels in the corpora cavernosa of the penis after sexual stimulation. Nitric oxide triggers a chemical cascade, dilating blood vessels and increasing blood flow into the penis, causing an erection. cGMP (another chemical in the cascade) levels must remain high to maintain the erection.

Phosphodiesterase, an enzyme, inactivates cGMP. Inactivating cGMP allows the smooth muscle in the walls of blood vessels to contract, decreasing blood flow into the penis and ending the erection. Oral ED medications block phosphodiesterase, keeping nitric oxide levels high, and blood continues to flow into the penis. Injectable ED medications are combinations of vasodilators that widen blood vessels and allow increased blood flow into the penis.

When the smooth muscle lining the corpora cavernosa fails to relax, blood remains trapped in these cavities for too long. This blood becomes depleted of oxygen and more acidic, depriving penile tissue of oxygen and nutrients. The swollen corpora cavernosa compresses penile tissue and causes damage as early as 4 to 6 hours from the start of an erection. Significant damage is seen after 12 hours of priapism, and irreversible damage occurs between 24 and 48 hours. 8,9

90% of men with ischemic priapism do not regain the ability to have penetrative sex if priapism lasts 24 hours or longer.8

How do you treat priapism?

Priapism is defined as an erection lasting four or more hours. Blood stasis and increased pressure in the penis increase over time. The longer priapism goes untreated past 4 hours, the more likely you will experience damage to the penis.

Trimix and other ED medications are ideally dosed to allow for an erection lasting 30 to 60 minutes. To reduce your risk of priapism, never combine ED medications or take a second dose of an ED medication within the same 24-hour period without talking to your doctor. Follow your doctor’s prescribing information and report any episodes of prolonged erection.

According to the American Urological Association Guidelines, erections lasting less than 1 hour do not require treatment, whereas erections lasting longer than 4 hours always require treatment. If you have had an erection for 4 hours, seek emergency treatment.

Erections lasting between 2 and 4 hours that are insufficient to penetrate without assistance would not require treatment.12

Treating Priapism: A Prolonged, Painful Erection

Erections lasting longer than 2 hours

If your erection lasts longer than 2 hours and is firm enough for penetrative sex, reduce your risk of priapism (defined as an erection lasting 4 hours or more). 4,10

  • Walk or jog up and down stairs to shunt blood from the penis to the legs.
  • Use an ice pack to reduce pain, constrict blood vessels, and make it easier to move about.
  • Take Pseudoephedrine (Sudafed) 30 to 60 mg by mouth. Sudafed is an over-the-counter medication that is kept behind the pharmacy counter and requires showing a photo ID to purchase it. Sudafed may be unsafe for people with high blood pressure or heart disease.

In one study, cold water compresses and vigorous exercise effectively treated a prolonged erection in 32.3% of men.4 In another study, climbing up and down stairs was effective for reversing a prolonged erection in 39.6% of men after taking QuadMix.10 Finally, pseudoephedrine was effective in treating 28% of men with prolonged erections after taking injectable ED medications.11  

The American Urological Association states that ice compresses, lying on your back, ejaculating, and using oral medications such as Sudafed may be helpful. However, there is no strong clinical evidence supporting their use. They should not be used in place of more established therapies if a fully rigid erection lasts 4 hours or more.12

Erections lasting 3 hours or more

If you have an erection that lasts longer than 3 hours, use the phenylephrine rescue medication prescribed by your Invigor Medical healthcare provider.

Phenylephrine is diluted with normal saline to a concentration of 100 units per mL. Phenylephrine for injection may be labeled in different ways:

  • 100 units per ml
  • 50 units per 0.5 ml
  • 100 μg/ml

Phenylephrine is the preferred first-line treatment for priapism because of its overall lower risk of causing systemic cardiovascular effects. Phenylephrine has a rapid onset and a short duration of action.9 Side effects from taking phenylephrine to treat priapism are rare.13 Potential side effects from using phenylephrine include:

  • High blood pressure
  • Headache
  • Reflex slowing of heart rate
  • Palpitations
  • Abnormal heart rhythm or rate

If you have high blood pressure, heart disease, or any concerns about using Sudafed or phenylephrine, discuss them with your doctor before taking Trimix and other ED medications.

As per Invigor Medical prescribing instructions, inject 50 units (.5 ml/50 mcg) into the penis every 5 minutes, as needed. Repeat every 5 minutes. Do not exceed a total dose of 5 mL within a 24-hour period. After injection, compress and massage the injection site to help distribute the medication throughout your penis. Continue treatment for up to 1 hour.

If an erection persists after one hour after starting phenylephrine treatment (4-hour erection), proceed to the ED (emergency room) to be treated.

Prolonged erections that last longer than 4 hours are a medical emergency and require emergent treatment.

If your penis is flaccid and non-painful, further treatment is not needed. To prevent further priapism episodes and potential cumulative damage to your penis, contact your prescriber at Invigor Medical to complete a Trimix/ED medication dosage adjustment questionnaire. Do not inject again without discussing a dosage change with your healthcare provider.

Author: Leann Poston, M.D.
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  • Levey HR, Segal RL, Bivalacqua TJ. Management of priapism: an update for clinicians. Ther Adv Urol. 2014 Dec;6(6):230-44. doi: 10.1177/1756287214542096. PMID: 25435917; PMCID: PMC4236300.
  • José Pablo Saffon Cuartas, Carolina Sandoval-Salinas, Juan M. Martínez, Héctor A. Corredor, "Treatment of Priapism Secondary to Drugs for Erectile Dysfunction", Advances in Urology, vol. 2019, Article ID 6214921, 4 pages, 2019.
  • Seyam, R., Mohamed, K., Akhras, A. et al. A prospective randomized study to optimize the dosage of trimix ingredients and compare its efficacy and safety with prostaglandin E1. Int J Impot Res 17, 346–353 (2005).
  • Podolej GS, Babcock C. Emergency Department Management Of Priapism. Emerg Med Pract. 2017 Jan;19(1):1-16. Epub 2017 Jan 1. PMID: 28027457.
  • Montague DK, Jarow J, Broderick GA, Dmochowski RR, Heaton JP, Lue TF, Nehra A, Sharlip ID; Members of the Erectile Dysfunction Guideline Update Panel; Americal Urological Association. American Urological Association guideline on the management of priapism. J Urol. 2003 Oct;170(4 Pt 1):1318-24. doi: 10.1097/ PMID: 14501756.
  • Pryor J, Akkus E, Alter G, Jordan G, Lebret T, Levine L, Mulhall J, Perovic S, Ralph D, Stackl W. Priapism. J Sex Med. 2004 Jul;1(1):116-20. doi: 10.1111/j.1743-6109.2004.10117.x. PMID: 16422992.
  • Spycher MA, Hauri D. The ultrastructure of the erectile tissue in priapism. J Urol. 1986 Jan;135(1):142-7. doi: 10.1016/s0022-5347(17)45549-2. PMID: 3941454.
  • M. Habous, M. Elkhouly, O. Abdelwahab et al., "Noninvasive treatments for iatrogenic priapism: do they really work? A prospective multicenter study," Urology Annals, vol. 8, no. 2, pp. 193–196, 2016.
  • Lowe FC, Jarow JP. Placebo-controlled study of oral terbutaline and pseudoephedrine in management of prostaglandin E1-induced prolonged erections. Urology. 1993 Jul;42(1):51-3; discussion 53-4. doi: 10.1016/0090-4295(93)90338-b. PMID: 8392235.
  • Bivalacqua TJ, Allen BK, Brock GB, et al. The diagnosis and management of recurrent ischemic priapism, priapism in sickle cell patients, and non-ischemic priapism: an AUA/SMSNA guideline. J Urol. 2022;208(1):43-52.
  • Sidhu AS, Wayne GF, Kim BJ, Anderson AGS, Cordon BH, Caso JR, Polackwich AS. The Hemodynamic Effects of Intracavernosal Phenylephrine for the Treatment of Ischemic Priapism. J Sex Med. 2018 Jul;15(7):990-996. doi: 10.1016/j.jsxm.2018.05.012. PMID: 29960632.
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