Behçet’s disease is a chronic inflammatory condition that causes blood vessel inflammation throughout the body, leading to painful ulcers in the mouth and genitals, eye inflammation, and skin lesions. It can also affect the joints, nervous system, and digestive tract. The disease follows a relapsing-remitting pattern, meaning symptoms flare up and then subside, sometimes for weeks or months at a time.
What Causes Behçet’s Disease
The exact cause remains unknown, but Behçet’s is classified as an autoinflammatory systemic vasculitis. That means the immune system attacks the body’s own blood vessels without a clear trigger. The inflammation affects both arteries and veins of all sizes, which is why symptoms can appear in so many different parts of the body.
The immune system’s T-cells become overactivated, flooding the bloodstream with inflammatory signaling molecules. This triggers white blood cells called neutrophils to swarm into tissues, particularly in the skin, mouth, and genitals. The resulting tissue damage is what produces the characteristic ulcers and skin lesions.
Genetics play a significant role. A gene variant called HLA-B51 is found in roughly 57% of people with Behçet’s disease, compared to about 18% of the general population. This genetic link helps explain the disease’s striking geographical pattern: it clusters along what was historically the Silk Road, from East Asia through the Middle East and into the Mediterranean basin. Turkey has the highest prevalence in the world. The disease is far less common in Northern Europe and the Americas.
Oral and Genital Ulcers
Painful mouth sores are the hallmark symptom and almost always the first to appear. They look similar to canker sores, starting as raised round lesions that quickly break open into painful ulcers. Most heal within one to three weeks, but they tend to come back repeatedly. Some people experience near-constant cycles of healing and recurrence.
Genital ulcers are the second defining feature. In men, they typically appear on the scrotum. In women, they develop on the vulva. These sores are painful and, unlike oral ulcers, often leave scars. The combination of recurrent oral and genital ulcers is one of the strongest indicators pointing toward a Behçet’s diagnosis.
Eye Inflammation
Eye involvement is one of the most serious aspects of Behçet’s disease because it can permanently damage vision. The inflammation typically affects the back of the eye (posterior uveitis), and in studies of patients with eye involvement, inflammation of the retinal veins was found in over 80% of cases. Swelling of the macula, the part of the retina responsible for sharp central vision, occurred in about 63% of patients with eye disease.
Over time, repeated flares of eye inflammation can lead to complications. Nearly 40% of patients with eye involvement develop cataracts as a result, and about 17% develop secondary glaucoma. Some patients experience a dramatic symptom called hypopyon, where a visible layer of white inflammatory cells collects in the front chamber of the eye. This is a hallmark finding that, combined with oral ulcers, strongly suggests Behçet’s disease.
Skin, Joint, and Other Symptoms
Skin problems are common and take several forms. Erythema nodosum produces tender, red nodules under the skin, usually on the shins. Some people develop acne-like lesions or pustules on the body. A distinctive feature of Behçet’s is something called pathergy: the skin overreacts to minor trauma, so a simple needle prick can produce a red bump or pustule within 24 to 48 hours. This reaction is actually used as a diagnostic test.
Joint pain and swelling affect many patients, typically involving the knees, ankles, wrists, or elbows. The arthritis in Behçet’s usually does not cause permanent joint damage, which distinguishes it from conditions like rheumatoid arthritis.
The disease can also affect the gastrointestinal tract, causing ulcers in the intestines that mimic inflammatory bowel disease. Neurological involvement, sometimes called neuro-Behçet’s, can cause headaches, confusion, balance problems, or stroke-like episodes when inflammation affects the brain or spinal cord.
How It’s Diagnosed
There is no single blood test or scan that confirms Behçet’s disease. Diagnosis relies on a scoring system called the International Criteria for Behçet’s Disease (ICBD). Points are assigned based on which symptoms are present: genital ulcers and eye inflammation each earn 2 points, while oral ulcers, skin lesions, vascular involvement, and a positive pathergy test each earn 1 point. A score of 3 or more points qualifies as a Behçet’s diagnosis.
This point system reflects the fact that Behçet’s is diagnosed by its pattern of symptoms rather than a single lab result. Because the symptoms overlap with many other conditions, including lupus, Crohn’s disease, and herpes simplex infections, diagnosis often takes time. Many patients see multiple specialists before receiving the correct diagnosis.
Treatment by Organ Involvement
Treatment depends on which parts of the body are affected, and the approach varies significantly from mild to severe disease.
For recurrent mouth and genital ulcers, colchicine (an anti-inflammatory medication) is the standard first-line treatment to reduce the frequency of flares. If ulcers keep recurring despite colchicine, stronger immune-suppressing medications are added. These include drugs that calm the overactive immune response or block specific inflammatory signals called TNF-alpha.
Eye disease involving the back of the eye requires more aggressive treatment from the start. Immune-suppressing medications are standard to prevent cumulative damage to vision. If a sudden, sight-threatening flare occurs, high-dose steroids or TNF-blocking drugs are used to control it quickly.
Blood clots, particularly deep vein thrombosis, are treated with steroids and immune-suppressing drugs rather than blood thinners alone. This is because in Behçet’s, clots form due to vessel wall inflammation, not a typical clotting disorder. Treating the underlying inflammation is the priority. For arterial aneurysms, particularly in the lungs, the inflammation needs to be controlled with medications before any surgical repair can be considered.
Neurological involvement calls for high-dose steroids during acute attacks, followed by long-term immune suppression to prevent further episodes.
Long-Term Outlook
For many people, Behçet’s disease becomes less severe over time, with flares becoming less frequent after the first several years. The disease tends to be most active in the 20s and 30s, which is also when it’s most commonly diagnosed.
The overall mortality rate in one large study was 5% over a median follow-up of about 7.7 years. The leading cause of death was major blood vessel disease, particularly arterial aneurysms, which accounted for nearly 44% of fatalities. Nervous system involvement and severe infections each accounted for about 12%.
Three factors were independently linked to a higher risk of serious outcomes: male sex (which carried nearly five times the risk), arterial involvement, and a high number of disease flares. Women and patients without vascular involvement generally have a more favorable prognosis. Early, consistent treatment aimed at reducing flare frequency is one of the most important factors in long-term outcomes.