Behçet's disease can cause a wide range of symptoms, but it's rare for someone with the condition to have all of them at once.

Most people experience times when the symptoms improve (remission) and times when they get worse (flare-ups or relapses).

Mouth ulcers

Almost everyone with Behçet's disease develops mouth ulcers. The ulcers look the same as normal mouth ulcers, but can be more numerous and painful. They most often develop on the tongue, lips, gums and the insides of the cheeks.

The ulcers usually heal within a couple of weeks without leaving any scarring, although they'll often return.

Genital ulcers

Like mouth ulcers, recurrent genital ulcers are also a common symptom of Behçet's disease.

In men, the ulcers usually appear on the scrotum. In women, they usually appear on the cervix (neck of the womb), vulva or vagina. However, genital ulcers can appear anywhere in the groin area, including on the penis.

The genital ulcers are usually painful and leave scarring in around half of all cases. Men may also experience inflammation (swelling) of the testicles and women may find the ulcers make having sex painful.

Genital ulcers caused by Behçet's disease are not contagious and cannot be spread through sexual intercourse.

Skin lesions

Many people with Behçet's disease also develop skin lesions. A lesion is any type of unusual growth or abnormality that develops on your skin, such as a bump or a discoloured area of skin.

Skin lesions that can occur in Behçet's disease include red, tender swellings on the legs called erythema nodosum and more widespread acne-like spots called pseudofolliculitis.

Skin lesions often heal within 14 days, although they may come back frequently. Erythema nodosum lesions may leave permanently discoloured areas of skin.

Inflammation of the joints

Behçet's disease affects the joints in around 1 in 2 people with the condition, causing arthritis-like symptoms such as pain, stiffness, swelling, warmth and tenderness.

The joints most often affected include the knees, ankles, wrists and small joints in the hands.

Unlike some conditions affecting the joints, permanent joint damage is rare in Behçet's disease and symptoms can usually be controlled successfully.

Inflammation of the eyes

Inflammation of the eyes is another common symptom of Behçet's disease, occurring in around 7 out of 10 cases. It often develops very suddenly.

Inflammation often affects the uveal tract, which is a group of connected structures inside the eye. Sometimes both eyes may be affected at the same time.

Inflammation of the uveal tract is known as uveitis and it can cause symptoms that include:

• painful red eyes
• floaters (dots that move across the field of vision)
• blurred vision

In the most severe cases of Behçet's disease, inflammation of the eyes can lead to permanent loss of vision. However, this is far less likely with early and appropriate treatment.

Sensitive skin

In some people with Behçet's disease, the skin is particularly sensitive to injury or irritation. This is known as pathergy.

For example, if a needle is used to prick the skin of someone who has pathergy, a large red bump would develop within 1 to 2 days that appears out of proportion to the original needle prick.

Gastrointestinal symptoms

Behçet's disease can cause inflammation of the stomach and bowel, which can lead to symptoms such as:

• feeling and being sick
• abdominal (tummy) pain
• indigestion
• loss of appetite
• diarrhoea with bleeding

Occasionally, the inflammation can cause the bowel to become damaged and bleed. Having blood in your poo is a possible symptom of inflammation of the internal lining of the bowel.

Blood clots

The inflammation of the lining of the blood vessels associated with Behçet's disease can sometimes cause blood clots to form.

One of the most common types of blood clot to affect people with Behçet's disease is deep vein thrombosis (DVT), where a blood clot develops in 1 of the deep veins of the body, usually in the legs.

Symptoms of DVT include:

• pain, swelling and tenderness in one of your legs (usually in the calf)
• a heavy ache in the affected area
• warm skin in the area of the clot
• redness of your skin, particularly at the back of your leg below the knee

DVT requires immediate medical treatment. If you suspect DVT,  go to your nearest accident and emergency (A&E) department immediately.

In people with Behçet's disease, careful assessment is needed to determine if it's safe to use blood thinning treatment for this complication. Treatment to control inflammation is usually more effective.

Cerebral venous thrombosis

A less common type of blood clot associated with Behçet's disease is cerebral venous thrombosis (CVT). This occurs when a blood clot develops inside the blood vessels that run through channels located between the outer and inner layer of your brain.

The blood clot can increase the pressure inside your skull and also lead to an interruption of the blood supply to the brain (stroke).

Symptoms of a CVT include:

• a severe headache – this has been described as a throbbing, piercing, band of pain, or as a very severe pain that suddenly appears out of nowhere
• slurred speech
• seizures (fits)
• hearing loss
• double vision
• stroke-like symptoms, such as muscle weakness or paralysis – but, unlike most strokes, both sides of the body can be affected

CVT is as a medical emergency. If you suspect a stroke, dial 999 immediately to request an ambulance.

Aneurysms

Inflammation of the blood vessels can cause the walls of your blood vessels to weaken. This causes the walls to bulge outwards as a result of blood pressure. The bulge is known as an aneurysm.

Aneurysms do not usually cause any noticeable symptoms unless the wall of the blood vessel becomes so weak that it enlarges or ruptures. This can place pressure on nearby areas and can sometimes lead to internal bleeding or organ dysfunction.

The symptoms of a ruptured aneurysm can vary depending on where in the body the aneurysm developed. Possible symptoms include:

• limb pain
• a sudden agonising headache
• dizziness
• breathlessness
• coughing up blood
• confusion
• loss of consciousness

Inflammation of the nervous system

Inflammation of the central nervous system (CNS) causes the most serious symptoms associated with Behçet's disease.

The symptoms of CNS inflammation usually develop quickly over the space of a few days, and can include:

• headache
• double vision
• loss of balance
• seizures (fits)
• partial paralysis on 1 side of the body
• behavioural or personality changes

General symptoms

It's also common for people with Behçet's disease to experience more general symptoms as a result of the condition, including periods of extreme physical or mental tiredness (fatigue). This can affect a person's ability to perform any sort of activity.

There's currently no cure for Behçet's disease, but a number of treatments can help to relieve symptoms and reduce the risk of serious complications.

Once a diagnosis of Behçet's disease has been confirmed, you'll usually be referred to several different specialists who have experience of treating the condition. They'll help draw up a specific treatment plan for you.

The specialists involved in your care may include:

• a dermatologist – a doctor who specialises in treating skin conditions
• an oral medicine specialist – a doctor or dentist who specialises in conditions affecting the mouth
• a rheumatologist – a doctor who specialises in treating joint conditions and conditions affecting the entire body
• an ophthalmologist – a doctor who specialises in treating eye conditions
• a neurologist – a doctor who specialises in treating conditions that affect the nervous system and brain

You may see more than 1 specialist during the same visit to hospital, to help with diagnosis and creating a treatment plan.

Your treatment plan usually involves the use of a combination of different medicines. Depending on the type and severity of your symptoms, you may only need to take medicines when you have a flare-up.

Alternatively, you may have to take medicines on a long-term basis to stop serious complications developing, such as vision loss.

Medicines

A number of different medicines can be used to treat the various symptoms of Behçet's disease, but the main types of medicines used can be broadly divided into:

• corticosteroids
• immunosuppressants
• biological therapies

Corticosteroids

Corticosteroids are powerful anti-inflammatory medicines that can be useful in reducing the inflammation associated with Behçet's disease.

Depending on the specific symptoms being treated, corticosteroids are available as:

• topical corticosteroids – applied directly to the area affected as eyedrops, creams or gels
• oral corticosteroids – these reduce inflammation throughout the body and come as tablets or capsules

Occasionally, corticosteroid injections may also be used.

Side effects depend on the form of corticosteroid you are taking. Side effects associated with topical corticosteroids are uncommon, but long-term use may lead to problems such as a thinning of your skin.

The long-term use of oral corticosteroids is associated with some potentially more serious side effects, including:

• increased appetite, leading to weight gain
• mood swings
• increased pressure in the eye (glaucoma)
• high blood pressure (hypertension)
• weak and brittle bones (osteoporosis)
• cataracts
• diabetes

If you do need to take oral corticosteroids on a long-term basis you may be given additional medicines to help treat these more serious side effects.

Immunosuppressants

Immunosuppressants are a type of medicine that reduces the activity of the immune system, which in turn interrupts the inflammation process that causes most of the symptoms of Behçet's disease.

Examples of immunosuppressants used to treat Behçet's disease include azathioprine, ciclosporin, methotrexate, mycophenolate mofetil and thalidomide.

These medications are usually available as tablets, capsules and injections. Colchicine, an anti-inflammatory medicine often used for gout, may also be beneficial.

While immunosuppressants can be useful in treating a wide range of Behçet's disease symptoms, they can also cause some potentially significant side effects.

For this reason, you'll be given careful advice about potential side effects and monitoring through blood tests. This is often co-ordinated by a specialist nurse.

General side effects of these medicines can include:

• effects on blood cells and liver function (regular monitoring of blood tests may be required)
• increased risk of infections – you should report any symptoms of a possible infection to your GP or healthcare team as soon as possible
• feeling and being sick
• abdominal (tummy) pain
• diarrhoea
• hair loss, which is usually temporary
• pins and needles
• muscle cramps and weakness

Some immunosuppressants can also cause birth defects and should not be taken if you're pregnant or planning a pregnancy.

If you're taking any of these medicines, you should ensure you talk to your specialist or GP about the possible effects of your medicines on a potential pregnancy.

Biological therapies

Biological therapies are a newer type of medicine that target the biological processes involved in the process of inflammation more selectively.

For example, 1 group of medicines called tumour necrosis factor-alpha inhibitors work by targeting the antibodies thought to cause much of the inflammation associated with Behçet's disease.

Biological therapies used to treat Behçet's disease include infliximab and interferon alpha. These may either be given directly into a vein (intravenously) or by injection under the skin (subcutaneous injection) at varying intervals.

While they're often effective, biological therapies are also very expensive. Your local hospital will usually only agree to fund biological therapies on the NHS if your symptoms are severe and other medicines have not been effective.

Biological therapies can also cause a range of side effects, including:

• increased risk of infections
• headaches
• dizziness
• feeling sick
• muscle and joint pain
• sudden, noticeable heartbeats (palpitations)
• increased heart rate (tachycardia)

As with immunosuppressant treatment, you should report any symptoms of a possible infection to your GP or healthcare team as soon as possible.

Treating specific symptoms

The specific medicines used for Behçet's disease vary depending on the symptom being treated.

Ulcers and skin lesions

Topical corticosteroids – such as creams, lozenges, mouthwashes and sprays – are usually the first treatment recommended for mouth and genital ulcers.

Some people find that using a corticosteroid inhaler is effective. These inhalers are commonly used to treat asthma and are normally used to spray the medicine into the lungs. However, rather than inhaling the steroids, you can use the inhaler to spray the steroids directly on to an ulcer.

If you have red, tender swellings on your legs (erythema nodosum), you may be prescribed colchicine tablets to reduce the inflammation of your skin.

For severe ulcers and lesions that do not respond to other treatments, other immunosuppressant tablets or biological therapies may be recommended.

Eye inflammation

Because of the potential risk of vision loss in serious cases, any eye inflammation caused by Behçet's disease should be carefully monitored by an ophthalmologist.

Treatment for eye problems often involves taking azathioprine and corticosteroid tablets, although corticosteroid eyedrops may also be useful.

In severe cases where these treatments have not helped, mycophenolate mofetil, ciclosporin or biological therapies may also be recommended.

Joint pain

For people with joint pain caused by Behçet's disease, conventional painkillers such as paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs) may sometimes help relieve the pain.

Daily colchicine tablets can also help by reducing the inflammation in your joints.

In severe cases where these treatments have not helped, azathioprine or biological therapies may be recommended.

Gastrointestinal symptoms

A number of different medicines may be used to help reduce inflammation of the stomach and bowel caused by Behçet's disease, including corticosteroids, immunosuppressants and biological therapies.

Sometimes the inflammation in your bowel causes it to become damaged and bleed. Medical treatment is usually successful, though rarely emergency surgery may be needed to stop the bleeding and remove the affected section of bowel.

Headaches

In cases of Behçet's disease, headaches are usually treated in the same way as migraines. This means there are 2 types of medicines that can be used:

• medicine to prevent the symptoms of a headache occurring, such as beta blockers
• medicine to help relieve the headache, such as NSAIDs and a type of medicine called triptans

Read more about treating migraine and preventing migraine.

Blood clots

It's not entirely clear whether blood clots associated with Behçet's disease should be treated in the same way as blood clots caused by other conditions, or whether using medicine to treat the underlying inflammation is more appropriate.

Normally, blood clots are treated with a type of medicine called an anticoagulant, which helps thin the blood and reduces the risk of the blood clot blocking the flow of blood.

However, the use of anticoagulants for Behçet's disease is controversial because the blood clots are slightly different to other clots – they tend to stick to the side of the blood vessel walls, rather than break off and travel through the bloodstream.

Using anticoagulants in Behçet's disease could also potentially increase the risk of any aneurysms rupturing and causing serious internal bleeding.

Blood clots are often treated with a combination of corticosteroid or immunosuppressant tablets to reduce the inflammation in the blood vessels. Anticoagulants are only used if you've been screened to make sure there are no aneurysms.

Aneurysms

Aneurysms caused by Behçet's disease are normally treated with a combination of corticosteroid and immunosuppressant tablets, or infusions of cyclophosphamide to reduce inflammation in the affected blood vessel and stop the aneurysm getting worse.

Surgery or procedures may also be considered. The aneurysm may be repaired or bypassed using small tubes called stents, or it can be blocked off. This is often combined with medical treatment to reduce or prevent the risk of recurrence.

For more information about how surgery is used to treat some common types of aneurysm, see treating brain aneurysms and treating abdominal aortic aneurysms.

Central nervous system inflammation

Relatively minor symptoms of central nervous system inflammation, such as double vision, may get better on their own without the need for treatment.

However, more serious symptoms, such as paralysis and behavioural changes, usually require treatment with medicine. This will often be in the form of corticosteroid or immunosuppressant injections, or biological therapies.

Pregnancy and fertility

Fertility is usually unaffected in women with Behçet's disease, but it's important that any pregnancy is planned where possible. This is because many of the medicines used to treat the condition, such as thalidomide, can cause birth defects.

It's recommended that you use at least 1 reliable method of contraception until you decide that you want to have a baby. You should discuss your plans to have a baby with your care team, who will be able to adjust your treatment plan to make your pregnancy as safe as possible.

There's little evidence that having Behçet's disease increases your risk of pregnancy-related complications, although there's a very small chance of your baby being born with a temporary condition called neonatal Behçet's disease.

The fertility of men with Behçet's disease may be affected. This can be the result of the condition itself or of a side effect of some of the immunosuppressant medicines. Colchicine may temporarily lower sperm count, but this often improves when treatment is stopped.

Where fertility is affected, further investigation – and, in some cases, fertility treatment such as in vitro fertilisation (IVF) – may be needed to conceive successfully.

Read more about treating infertility.

Neonatal Behçet's disease

There's a possibility that a baby can be born with a type of Behçet's disease that can cause ulcers on the baby's genitals and mouth. This type of Behçet's disease, known as neonatal Behçet's disease, is extremely rare, with only 1 or 2 cases being reported every few years.

Corticosteroids can be used to help relieve symptoms of neonatal Behçet's disease. The condition usually resolves within 6 to 8 weeks after the birth.