Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Behçet Disease

(Behçet's Disease)


Alexandra Villa-Forte

, MD, MPH, Cleveland Clinic

Reviewed/Revised May 2022 | Modified Sep 2022
Topic Resources

Behçet disease is chronic blood vessel inflammation (vasculitis) that can cause painful mouth and genital sores, skin lesions, and eye problems. The joints, nervous system, and digestive tract may also become inflamed.

  • Typically, sores appear, disappear, and reappear in the mouth and on the genitals and skin.

  • Doctors base the diagnosis on established criteria.

  • Treatment depends on the areas affected but typically involves corticosteroids and sometimes other drugs that suppress the immune system.

Behçet disease occurs worldwide but is most common in the area along the silk route from the Mediterranean to China. It is relatively uncommon in the United States. It occurs nearly equally in men and women, typically beginning during the 20s, but tends to be more severe in men. Occasionally, the syndrome develops in children. The cause of Behçet disease is unknown. The risk appears to be higher in people who have certain genetic characteristics, such as people who have a gene Genes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body or the code for functional ribonucleic... read more Genes called HLA-B51.

Symptoms of Behçet Disease

Almost everyone with Behçet disease has recurring, painful mouth sores, similar to severe canker sores (recurrent aphthous stomatitis Recurrent Aphthous Stomatitis Recurrent aphthous stomatitis (canker sores, or aphthous ulcers) is the presence of small, painful sores (ulcers) inside the mouth that typically begin in childhood and recur frequently. Mouth... read more Recurrent Aphthous Stomatitis ). Mouth sores are usually the first symptom of Behçet disease. Sores may appear anywhere in the mouth, such as on the tongue, gums, and lining of the mouth, and often occur in clusters. The sores are round or oval, less than half an inch to about 4 inches (about 1 to 10 centimeters) in diameter, and shallow or deep with a yellowish center. The sores last 1 to 2 weeks.

Although other kinds of mouth sores are very common (for example, cold sores caused by the herpes simplex virus), the sores caused by Behçet disease tend to last longer and be more severe.

Sores may also appear on the genital organs. Sores on the penis, scrotum, or vulva tend to be painful. Sores in the vagina may be painless.

People may have a fever and a general feeling of illness (malaise). Other symptoms appear days to years later:

Diagnosis of Behçet Disease

  • Established criteria

  • Blood tests

No laboratory tests can confirm Behçet disease, but doctors can base the diagnosis on an established set of criteria. Doctors suspect the disorder in people, particularly young adults, who have had 3 episodes of mouth sores in 1 year and 2 of the following criteria:

  • Recurring genital sores

  • Characteristic eye problems

  • Skin lesions that look like bumps under the skin, acne, or ulcers

  • Skin bumps or blisters triggered by a slight injury

However, symptoms may resemble those of many other disorders, including reactive arthritis Reactive Arthritis Reactive arthritis (previously called Reiter syndrome) is a spondyloarthritis causing inflammation of the joints and tendon attachments at the joints, often related to an infection. Joint pain... read more Reactive Arthritis (previously called Reiter syndrome), lupus (systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more Systemic Lupus Erythematosus (SLE) ), Crohn disease Crohn Disease Crohn disease is an inflammatory bowel disease where chronic inflammation typically involves the lower part of the small intestine, the large intestine, or both and may affect any part of the... read more Crohn Disease , herpes Herpes Simplex Virus (HSV) Infections Herpes simplex virus infection causes recurring episodes of small, painful, fluid-filled blisters on the skin, mouth, lips (cold sores), eyes, or genitals. This very contagious viral infection... read more Herpes Simplex Virus (HSV) Infections , and ulcerative colitis Ulcerative Colitis Ulcerative colitis is a chronic inflammatory bowel disease in which the large intestine (colon) becomes inflamed and ulcerated (pitted or eroded), leading to flare-ups (bouts or attacks) of... read more . The diagnosis may take months to make because doctors look for a pattern of symptoms that subside (called remission) and return (called relapse) to help identify the syndrome. Mouth sores can resemble other, more common sores, such as fever blisters (caused by the herpes simplex virus).

Blood tests are done. They cannot identify the disease but can confirm that inflammation is present.

The diagnosis of Behçet disease is difficult to confirm when people have only mouth sores and possibly sores on their genitals or skin. The diagnosis is much easier to make when other symptoms, such as inflammation of the eyes or blood vessels, are present.

Prognosis for Behçet Disease

Symptoms of Behçet disease can come and go unpredictably, becoming very disruptive. Symptoms or symptom-free periods (remissions) may last weeks, years, or decades. Many people eventually go into remission. Occasionally, damage to the nervous system, digestive tract, or blood vessels is fatal. The risk of death is highest for young men and people with disease of the arteries or a high number of flare-ups. With time, the disease seems to quiet down.

Treatment of Behçet Disease

  • Corticosteroids and other immunosuppressants

  • Other drugs, depending on symptoms

There is no cure, but treatment of Behçet disease can usually relieve specific symptoms. Which drugs are used depends on which organ is affected and how severe the disease is. For example, the following may be used:

  • For inflamed eyes and skin sores: A corticosteroid (used to reduce inflammation) can be applied to the eyes or skin. Azathioprine (a drug that suppresses the immune system Overview of the Immune System The immune system is designed to defend the body against foreign or dangerous invaders. Such invaders include Microorganisms (commonly called germs, such as bacteria, viruses, and fungi) Parasites... read more [immunosuppressant]) helps preserve sharpness of vision, prevents new eye sores from forming and help existing sores heal. Methotrexate taken by mouth can hep reduce eye inflammation. Interferon alfa and tumor necrosis factor (TNF)–inhibiting drugs given by injection can help people who have eye problems.

  • For severe inflammation of the eyes or nervous system: The immunosuppressant cyclosporine may be used when eye inflammation is severe or when the corticosteroid prednisone does not adequately control symptoms.

  • For mouth and genital sores and joint pain: Corticosteroid creams, local anesthetic preparations, and sucralfate can be applied to the sores. Colchicine (used to treat gout) can be taken by mouth to prevent new sores and can reduce joint pain. Dapsone is taken by mouth and may decrease the number of mouth and genital sores and decrease how long they last. Azathioprine is taken by mouth and also can help heal mouth and genital sores and reduce joint pain. Etanercept, which is a tumor necrosis factor inhibitor (and thus suppresses the immune system), helps prevent new mouth sores. It is given by injection. Sometimes another tumor necrosis factor inhibitor (infliximab or possibly adalimumab) is used instead of etanercept. Interferon alfa can also be given by injection if colchicine does not help. Apremilast can be used to decrease the pain and number of mouth sores. Thalidomide, which is rarely used, can be taken by mouth and may help mouth, genital, and skin sores heal, but the sores may return when the drug is stopped.

Cyclophosphamide and chlorambucil are used when other drugs are ineffective or when life-threatening or serious eye or nervous system complications develop.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • Vasculitis Foundation: Provides information for patients about vasculitis, including how to find a doctor, learn about research studies, and join patient advocacy groups

Drugs Mentioned In This Article

Generic Name Select Brand Names
Azasan, Imuran
Jylamvo, Otrexup, Rasuvo, RediTrex, Rheumatrex, Trexall, Xatmep
Cequa, Gengraf , Neoral, Restasis, Sandimmune, SangCya, Verkazia, Vevye
Deltasone, Predone, RAYOS, Sterapred, Sterapred DS
Cyclophosphamide, Cytoxan, Neosar
quiz link

Test your knowledge

Take a Quiz!