context: Erections can’t happen without proper blood flow. Normally when a man gets aroused, the arteries in his pelvis and penis relax and expand, bringing more blood to spongy tissues in the penis. At the same time, the valves in the veins close, trapping blood in the area and causing an erection. After the excitement ends, the vein valves open, the blood flows out, and the penis returns to its usual state. Blood flow that’s not normal can cause priapism, an erection that lasts for more than 4 hours, is usually painful, and may happen without sexual arousal. It can happen to males of all ages, including newborns. There are two main types: Low-flow or ischemic priapism: This type happens when blood gets trapped in the erection chambers. Most of the time, there’s no clear cause, but it may affect men with sickle-cell disease, leukemia (cancer of the blood), or malaria. If you don’t get treatment right away, it can lead to scarring and permanent erectile dysfunction ( ED). High-flow or non-ischemic priapism: This type is more rare than low-flow and is usually less painful. It often happens when an injury to the penis or the area between the scrotum and anus, called the perineum, ruptures an artery, which prevents blood in the penis from moving normally. Sickle cell anemia: Scientists think about 42% of men with sickle cell disease will get priapism at some point. Medications : Many men get the condition when they use or misuse some types of medicine. Drugs that may cause priapism include the depression treatment trazodone HCL ( Desyrel), or chlorpromazine ( Thorazine), which treats some mental illnesses. The pills or shots that treat ED may also cause priapism. Other causes include: An injury to the spinal cord or genital area Black widow spider bites and scorpion stings Carbon monoxide poisoning Using street drugs like marijuana and cocaine It’s rare, but priapism can happen because of cancers that affect the penis and prevent blood from flowing out of the area. If you think you might have priapism, you need to get medical care right away. Tell your doctor: How long you’ve had the erection How long your erections usually last Any drugs, legal or illegal, that you’ve used If the problem happened after an injury Your doctor will review your medical history and do a thorough physical exam to figure out what’s causing your problem. He’ll check your rectum and belly for any signs of cancer. You may also need to see a urologist for more screening tests, including: Blood tests An imaging test called a color Doppler ultrasound, which shows how blood is flowing in your penis An X-ray called an arteriogram that detects a dye your doctor injects into an artery The goal of any treatment for the condition is to make the erection go away and prevent ED. Options include: Ice packs: They may bring down swelling for high-flow priapism. Removing the blood: After your doctor numbs your penis, he’ll use a needle to drain blood from the area to ease pressure and swelling. Medicines: For low-flow priapism, your doctor can inject drugs called alpha-agonists into your penis. They make the blood vessels narrow, bringing less blood the area and easing swelling. You might be able to take pills instead of getting an injection. Blocking the artery: A doctor will block the blood vesselthat’s causing the problem, a procedure called an arterial embolization. Doctors sometimes use it for high-flow priapism. Tying off the artery: When a ruptured artery causes priapism, a doctor will do an operation to tie it off, called surgical ligation. This is also for high-flow priapism. Surgical shunt: It’s passageway that a surgeon creates in the penis to allow the blood to drain. The procedure is best for low-flow priapism, but it does mean a high risk of ED later on. If you think you have priapism, don't try to treat it yourself. Instead, get emergency care as soon as possible. Most people recover completely when they get treatment quickly. But the longer you go without medical care, the greater your risk of lasting problems getting and keeping erections.