Behçet’s disease is a chronic inflammatory condition that attacks blood vessels throughout the body, causing painful ulcers in the mouth and genitals, eye inflammation, skin problems, and potentially serious damage to the brain, heart, and digestive system. It affects blood vessels of all sizes, both arteries and veins, which is why its symptoms can show up in nearly any organ. The condition follows a pattern of flare-ups and remissions, and its severity varies widely from person to person.
Why It Happens
Behçet’s disease is classified as an auto-inflammatory vasculitis, meaning the immune system mistakenly triggers inflammation in blood vessel walls. The exact cause remains unknown, but the process involves overactive immune cells. A specific type of immune cell (Th1 cells) ramps up and floods the bloodstream with inflammatory signaling molecules. This chain reaction draws white blood cells called neutrophils to blood vessel walls and surrounding tissues, where they cause direct damage.
Antibodies that target the cells lining blood vessels also play a role, contributing to the vascular dysfunction that drives many of the disease’s complications. The result is inflammation that can strike almost anywhere there are blood vessels, which explains the wide range of symptoms.
Who Gets It
Behçet’s disease is sometimes called “Silk Road disease” because it’s most common in populations along the ancient trade route stretching from East Asia to the Mediterranean. Turkey has by far the highest prevalence at 421 cases per 100,000 people. Iran follows at 80 per 100,000, then Saudi Arabia (20), Iraq (17), Israel (15.2), and Japan (13.5). In Western countries, it’s much rarer: 5.2 per 100,000 in the United States, 7.1 in France, and just 0.64 in the United Kingdom.
Genetics partly explain this geographic pattern. A gene variant called HLA-B*51 is strongly associated with the disease. In Silk Road nations, 50 to 80% of people with Behçet’s carry this variant, compared to 20 to 25% of the general population in those regions. In the U.S. and northern Europe, about 15% of Behçet’s patients carry the variant versus only 2 to 8% of the general population. Carrying HLA-B*51 increases risk but doesn’t guarantee disease, and many people with Behçet’s don’t carry it at all. Symptoms typically first appear between the ages of 20 and 40.
Mouth and Genital Ulcers
Recurrent oral ulcers are the hallmark symptom and often the first sign. These aren’t ordinary canker sores. They tend to be larger, more painful, and come back repeatedly, sometimes in clusters. They can appear on the tongue, lips, gums, and inner cheeks. Most people with Behçet’s experience oral ulcers at some point during the course of the disease.
Genital ulcers are similar in appearance and pain level, occurring on the scrotum or vulva. They can leave scars, which actually helps distinguish them from oral ulcers (which typically heal without scarring). Both types of ulcers tend to flare in cycles, disappearing for weeks or months before returning.
Eye Inflammation and Vision Risk
Eye involvement is one of the most serious aspects of Behçet’s disease. Uveitis, an inflammation inside the eye, develops in 50 to 90% of patients over the course of the disease. In 10 to 20% of cases, uveitis is actually the first symptom that leads to diagnosis. It typically develops two to three years after the disease begins.
The stakes are high. Repeated bouts of uveitis cause cumulative damage, and 16 to 25% of patients with Behçet’s-related uveitis lose significant vision within 5 to 10 years of onset. Behçet’s is considered one of the most severe causes of non-infectious uveitis. Symptoms include eye pain, blurred vision, light sensitivity, and redness. Because the inflammation can affect both the front and back of the eye, regular eye exams are essential for anyone with Behçet’s.
Vascular Complications
Because the disease targets blood vessels, vascular problems are a major concern. In one large study, about 30% of patients developed vascular or cardiac complications. Deep vein thrombosis (blood clots in deep veins, usually in the legs) is the most common vascular problem, accounting for roughly 62.5% of vascular events. Superficial vein clots make up about 23%, while blood clots in the pulmonary arteries occur in around 14% of cases. Aneurysms, where weakened vessel walls balloon outward, develop in about 9% of patients with vascular involvement.
These complications can affect vessels anywhere in the body, including the coronary arteries and the aorta. Vascular involvement generally signals more aggressive disease and requires closer monitoring.
Neurological Involvement
The central nervous system is affected in a significant minority of patients, a condition called neuro-Behçet’s. The brain can be damaged in two main ways: through immune-driven inflammation of brain tissue (meningoencephalitis), which accounts for about 75% of neurological cases, or through blood clots forming in the veins that drain the brain.
The brainstem is the most commonly affected area, though inflammation can also strike deeper brain structures, the spinal cord, or cranial nerves. Onset is usually gradual rather than sudden, and neurological flares often coincide with worsening of other Behçet’s symptoms like ulcers, skin lesions, or fever. Headaches are common in Behçet’s patients generally, but a new or worsening headache pattern alongside neurological symptoms like weakness, vision changes, or difficulty with balance warrants urgent evaluation.
How It’s Diagnosed
There’s no single blood test or scan that confirms Behçet’s disease. Diagnosis relies on recognizing a pattern of symptoms. The International Criteria for Behçet’s Disease uses a point system: oral ulcers, genital ulcers, and eye lesions each score 2 points, while skin lesions, central nervous system involvement, and vascular problems each score 1 point. A total of 4 or more points classifies someone as having the disease.
One unusual diagnostic tool is the pathergy test, where a doctor pricks the skin with a sterile needle and checks 24 to 48 hours later for an exaggerated bumpy reaction. This test reflects the overactive immune response characteristic of Behçet’s. However, its usefulness depends heavily on geography. In Turkey, Japan, and Eastern Mediterranean countries, 50 to 88% of Behçet’s patients test positive. In the U.S. and England, positivity rates drop below 20%, making it far less reliable. When used, it adds 1 point to the diagnostic score. The test has high specificity (96 to 98%), meaning a positive result strongly suggests Behçet’s, but its sensitivity is low (30 to 43%), so a negative result doesn’t rule it out.
Treatment Approach
Treatment depends on which organs are affected and how severely. For mouth and genital ulcers alone, the approach starts conservatively. Topical steroid creams or gels applied directly to ulcers help manage pain and speed healing. Colchicine, an anti-inflammatory pill, is typically the first medication tried for preventing recurrent skin and mucosal flares, particularly when genital ulcers or a type of painful skin nodule called erythema nodosum is the main problem. It’s well tolerated and considered a good starting point for people whose disease is limited to the skin and mucous membranes.
When the disease affects the eyes, blood vessels, brain, or gut, the treatment approach shifts significantly. These forms of Behçet’s carry a risk of permanent organ damage, so suppressing inflammation quickly and preventing relapses becomes the priority. Immunosuppressive medications are usually necessary. Options include drugs that broadly dial down the immune system, as well as newer biologic therapies that block specific inflammatory molecules like TNF-alpha. The choice depends on which organ system is involved and how the patient responds.
For skin breakouts that look like acne, standard acne treatments (topical or oral) are often effective. Leg ulcers require a more tailored approach because they can result from either poor vein circulation or inflamed blood vessels, each needing different management. The use of blood thinners in patients with clotting complications remains a nuanced decision, weighed against the risk of bleeding from inflamed, weakened vessels.
Living With Behçet’s Disease
Behçet’s is a lifelong condition, but its course is unpredictable. Some people experience mild, intermittent mouth ulcers and skin problems that respond well to basic treatment. Others face serious organ involvement that requires long-term immunosuppressive therapy. The disease tends to be more severe in young men, particularly those diagnosed in their 20s, and in populations along the Silk Road where the genetic predisposition is strongest.
Flares can be triggered by stress, illness, or sometimes nothing identifiable at all. Over time, the disease often becomes less active, with flares becoming less frequent and less severe as patients reach their 40s and 50s. The key to preserving long-term health, especially vision and neurological function, is early recognition and consistent treatment of organ-threatening inflammation.