Marijuana may have caused a man's erections to last up to 12 HOURS

Marijuana may have caused a man’s erections to last up to 12 HOURS because it switched off the signals in his brain for it to end, new medical study finds in the first case of its kind

  • Study appeared in this month’s issue of Journal of Cannabis Research 
  • Experts write of case study of healthy, 32-year-old African American man 
  • The man went to emergency room twice complaining of long-lasting erections 
  • In one instance, the erection lasted 12 hours, according to researchers
  • Man told doctors he frequently used cannabis, causing episodes of priapism 

A 32-year-old man who was recently treated at the hospital for several longer-than-normal erections, including one that lasted 12 hours, likely had the condition due to frequent use of marijuana, researchers say.

A team of doctors at Coliseum Medical Centers in Macon, Georgia, says it is the ‘first known case of cannabis-associated priapism in a patient where all other known causes of priapism have been excluded.’

Priapism is a long-lasting, painful erection that usually lasts more than four hours and is unrelated to sexual activity.

If untreated, priapism, which is often caused by use of prescription medication like anti-depressants or illicit drug use such as cocaine, can cause permanent damage to the penis.

This is the first time that researchers have recorded an instance in which priapism was believed to have been caused by consistent use of cannabis.

Experts wrote about the unusual case of the 32-year-old healthy African American man who was admitted to the hospital after complaining about persistent erections.

American researchers say that they have found an instance in which cannabis was the likely cause of a healthy, 32-year-old man getting erections that lasted hours

According to the Journal of Cannabis Research, he went to the hospital’s emergency room complaining of an erection that lasted for 12 hours and was unrelated to sexual activity.

Two weeks later, the same patient paid another visit to the emergency room – this time because of a six-hour erection.

During the hospital visits, he was given an injection of phenylephrine, which helped the erection subside.

The patient told doctors that he smoked cannabis ‘several nights per week for the past six months’ – including ‘within the two hours period prior to each presenting episode of priapism.’

During the six-month period, the patient reported that he had at least four instances of erections lasting close to four hours. The erections eventually passed on their own.

Doctors said that the patient did not have a family history of sickle cell anemia.

He also told doctors that he began using cannabis at age 16. During that time, he had several long-lasting erections of up to four hours that subsided on their own.

In his twenties, the man said he stopped using cannabis and had never experienced priapism during that period.

The study was done by researchers at the Coliseum Medical Centers in Macon, Georgia

He also said he did not have any history of psychiatric disease.

According to the study, the man said he never took prescribed or over-the-counter medications.

‘On physical exam, the patient was mildly hypertensive with an erect, swollen, and tender penis,’ according to the study.

‘A repeat needle aspiration with (1000 mcg total) of phenylephrine was completed, again resulting in successful detumescence.

‘A urine drug screen was consistent with cannabis use without other drug use.

‘A complete blood count revealed no anemia and a normal mean corpuscular volume.

‘The patient was again referred to urology and internal medicine on an outpatient basis for further workup; however he was lost to followup in this period.’

The Georgia researchers referred back to previous case studies of priapism, where patients had underlying causes such as sickle-cell disease, diabetes, and use of other substances like cocaine and anabolic steroids.

This patient, however, was different.

‘He had no medical history other than mild hypertension, he took no medications, and used only cannabis, supported by his urinary drug screen,’ the report says.

‘Further, his history exhibited a convincing correlation between his cannabis use and his episodes of recurrent priapism.’

The researchers could not definitively state why cannabis caused the long-lasting erection, though they did put forward a theory which states that chemicals in the plant may have switched off signals in the brain that end normal erections.

Another possibility put forward by researchers is the effect of cannabis on the blood flow.

Blood vessels tend to dilate when using marijuana. Experts say this, too, ‘could potentiate the unrelenting erection notable in priapism.’ 


Priapism is a long-lasting painful erection which can cause permanent damage to your penis if not treated quickly, including scarring and permanent erectile dysfunction. 

Priapism can occur in all age groups, including newborns. However, it usually affects men in two different age groups: between the ages of 5 and 10, and 20 and 50. 

The condition develops when blood in the penis becomes trapped and is unable to drain. 

There are two types of priapism: low-flow and high-flow.

Low-flow priapism: This is the result of blood being trapped in the erection chambers. It often occurs without a known cause in men who are otherwise healthy, but it also affects men with sickle-cell disease, leukemia (cancer of the blood), or malaria.

High-flow priapism: This is more rare and is usually not painful. It is the result of a ruptured artery from an injury to the penis or the perineum (the area between the scrotum and anus), which prevents blood in the penis from circulating normally.  


Priapism most commonly affects people with sickle cell disease.

Less common causes include blood-thinning medicines, like warfarin, some antidepressants, recreational drugs – like cannabis and cocaine – some medicines for high blood pressure, other blood disorders, like thalassaemia and leukaemia and some treatments for erection problems.

Malignant priapism, which is secondary to cancer, is rarely reported and has poor outcomes. 

It occurs when the cancer causes the penis to become rigid and can only be relieved when the cancer is treated.

An erection that lasts longer than four hours is known as priapism and is a medical emergency. 


  • try to urinate
  • have a warm bath or shower
  • drink lots of water
  • go for a gentle walk
  • try exercises such as squats or running on the spot
  • take painkillers like paracetemol if you need to  


  • do not apply ice packs or cold water to your penis – this can make things worse
  • do not have sex or masturbate – it won’t make your erection go away
  • do not drink alcohol
  • do not smoke 

The goal of all treatment is to make the erection go away and preserve the ability to have erections in the future, and may include surgical ligation, intravenous injection and surgical shunt. 

Source: NHS and Cleveland Clinic 


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