Overview

Behcet (beh-CHET) disease, also called Behcet syndrome, is a rare condition. It causes blood vessel swelling, called inflammation, throughout the body.

Behcet disease symptoms can seem like they aren't related at first. They can include mouth sores, eye irritation and swelling, skin rashes and sores, and genital sores.

Treatment involves medicines to ease symptoms of Behcet disease and to prevent serious complications, such as blindness.

Symptoms

Behcet disease symptoms vary from person to person. Symptoms can come and go or become less serious over time. Symptoms depend on which parts of the body the condition affects.

Behcet disease most often affects the following:

  • Mouth. Painful mouth sores that look like canker sores are the most common sign of Behcet disease. They begin as raised, round sores in the mouth. They quickly turn into painful ulcers.

    The sores most often heal in 1 to 3 weeks. But they often come back.

  • Skin. Some people get sores that look like acne on their bodies. Others get raised and tender growths called nodules on their skin, mainly on the lower legs.
  • Genitals. Open sores can happen on the scrotum or the vulva. The sores are most often painful and can leave scars.
  • Eyes. Irritation and swelling, called inflammation, in the eye causes redness, pain and blurred vision. Called uveitis, this inflammation most often affects both eyes. In people with Behcet disease, these symptoms can come and go.
  • Joints. Joint swelling and pain often affect the knees in people with Behcet disease. The ankles, elbows or wrists also might be involved. Symptoms can last 1 to 3 weeks and go away on their own.
  • Blood vessels. Swelling, called inflammation, in veins and arteries can cause redness and pain. It can cause a blood clot, which leads to swelling in the arms or legs. Inflammation in the large arteries can lead to complications. These include bulges in the artery that can burst, called aneurysms, and narrowed or blocked blood vessels.
  • Digestive system. Several symptoms can affect the network of organs that digest food, called the digestive system. Symptoms may include belly pain, diarrhea and bleeding.
  • Brain. Swelling, called inflammation, in the brain and nervous system can cause headache, fever, confusion, poor balance or stroke.

When to see a doctor

Make an appointment with your healthcare professional if you have symptoms that might be Behcet disease. If you've been diagnosed with the condition, see your health professional if you get new symptoms.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

We use the data you provide to deliver you the content you requested. To provide you with the most relevant and helpful information, we may combine your email and website data with other information we have about you. If you are a Mayo Clinic patient, we will only use your protected health information as outlined in our Notice of Privacy Practices. You may opt out of email communications at any time by clicking on the unsubscribe link in the email.

Causes

Behcet disease might be an autoimmune disorder, which means the body's immune system attacks some of its own healthy cells by mistake. It's likely that gene changes and factors in the environment play a role.

Experts believe that swelling of the blood vessels, called vasculitis, causes the symptoms of Behcet disease. The condition can involve arteries and veins of all sizes. Vasculitis can damage blood vessels all through the body.

Some genes might make people more likely to get Behcet disease. Some researchers think that a germ can trigger the disease in people who have these genes.

Risk factors

Factors that might increase your risk of Behcet disease include:

  • Age. Behcet disease most often affects people in their 20s and 30s. But children and older adults also can have the condition.
  • Country. People from countries in the Middle East and East Asia, including Turkey, Iran, Japan and China, are more likely to get Behcet disease.
  • Sex assigned at birth. Behcet disease can happen to anyone. But the disease is most often worse in people assigned male at birth.
  • Genes. Certain genes may be linked with a higher risk of getting Behcet disease.

Complications

Complications of Behcet disease depend on symptoms. For instance, untreated uveitis can lead to loss of vision or blindness. If you have eye symptoms of Behcet disease, see an eye specialist, called an ophthalmologist, regularly. Treatment can help prevent this complication.

April 25, 2025
  1. Ferri FF. Behcet disease. In Ferri's Clinical Advisor 2025.Elsevier; 2025. https://www.clinicalkey.com. Accessed Aug. 7, 2024.
  2. AskMayoExpert. Behcet syndrome. Mayo Clinic, 2023.
  3. Smith EL, et al. Clinical manifestations and diagnosis of Behcet syndrome. https://www.update.com/contents/search. Accessed Aug. 7, 2024.
  4. Medical summary of Behcet's disease. American Behcet's Disease Association. https://www.behcets.com/medical-summary. Accessed Aug. 7, 2024.
  5. Smith EL, et al. Treatment of Behcet syndrome. https://www.update.com/contents/search. Accessed Aug. 7, 2024.
  6. Saadoun D, et al. Behcet's syndrome. The New England Journal of Medicine. 2024; doi:10.1056/NEJMra2305712.