What Is Bullous Pemphigoid?

Bullous pemphigoid is an autoimmune condition that causes large, fluid-filled blisters on the skin. (The word “bullous” is a medical term for blister.) It mostly affects older people but less commonly appears in children or adolescents. It can pose a serious health risk, particularly in older people with other major medical problems.

Bullous pemphigoid is a rare disease, but it has become slightly more common in recent years. Researchers aren’t exactly sure why this is, but a number of factors may be involved, like the increasing age of the population, the side effects of other drugs, or just better recognition of the disease.

One Type of Autoimmune Blistering Disorder

Bullous pemphigoid is one type of a much larger group of conditions called autoimmune bullous disorders. Bullous pemphigoid is the most common form of these disorders.

All these disorders can cause blistering due to an abnormal reaction of the body's immune system, but their underlying causes and symptoms can differ.

Bullous Pemphigoid Symptoms

Bullous pemphigoid causes itchy blisters on the skin, typically in areas where the body flexes. Symptoms are chronic and often go through cycles of disease improvement and worsening. Less commonly, symptoms go away on their own without coming back.

Many people experience initial symptoms before blisters actually appear. For instance, at first areas of the skin may become itchy, red, and painful, with an eczema-like rash appearing in a variety of shapes over large areas of the body. These symptoms may last weeks or months before further symptoms are experienced.

Next, fluid-filled blisters (called “bullae”) may form on top of this red, itchy base. The blisters often burst open, leaving raw, red skin. The blisters can cover large parts of the body, but they commonly develop on the limbs and face. Less often, blisters occur in areas like the lips and genital region. 

When blisters break open, they may become infected, leading to symptoms like increased redness and heat in the area. Sometimes people experiencing bullous pemphigoid need to be hospitalized to prevent infection if they have many raw, open areas on their body.

Causes

Bullous pemphigoid is a type of autoimmune disease, which causes your immune system to attack healthy cells in response to what it mistakes as a threat. This can lead to damaged tissue. Ultimately, it’s this tissue damage that causes the disease’s symptoms. 

Skin Anatomy

Many different types of cells make up the complex organ that is your skin. Together, they do an important job of protecting the interior of the body from injury and infection.

Your skin undergoes a lot of physical stress as it interacts with the world. It’s important that the membranes of cells that make up your skin attach very tightly to each other to give your skin strength and resiliency. Your skin cells make different proteins that help them form these strong bonds.

Scientists don’t completely understand what goes wrong in autoimmune blistering diseases like bullous pemphigoid, but part of the reaction seems to be caused by the formation of antibodies against a variety of these skin proteins and fibers.

In bullous pemphigoid, scientists believe antibodies form against two different proteins found between the epidermis (the outermost layer of skin) and the deeper dermis, preventing the two layers from attaching to one another. (These specific proteins are called BP180 and BP230.)

In other similar autoimmune blistering diseases, antibodies against some related but distinct proteins may be formed.

Inflammation occurs around these proteins, and they may not be able to work normally to create the important attachment process between the cell layers. This and further inflammation can cause some cells to die off, leading to blister formation.  

Predisposing Factors

Like other autoimmune diseases, there seems to be a genetic component to bullous pemphigoid.

Also, the risk of having bullous pemphigoid is higher in people who have certain other medical conditions. People with the following illnesses are at greater risk of developing bullous pemphigoid in later adulthood:

• Multiple sclerosis
• Psoriasis
• Rheumatoid arthritis
• Autoimmune thyroid disease

Physical trauma to the skin may also trigger the disease in certain people. For example, this might happen after radiation therapy, exposure to ultraviolet (UV) radiation (including tanning beds), or chemical burns. 

Sometimes, starting certain medications trigger bullous pemphigoid. Some of the drugs that may do this are:

• Antibiotics like Moxatag (amoxicillin)
• Beta-blockers like Tenormin (atenolol)
• Calcium-channel blockers like Norvasc (amlodipine)
• Nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil (ibuprofen)
• Diuretics like Lasix (furosemide)
• Certain diabetes drugs like Januvia (sitagliptin)
• TNF blockers (tumor necrosis factor blockers) like Remicade (infliximab)
• Immune checkpoint inhibitors like Keytruda (pembrolizumab)

Diagnosis

A diagnosis of bullous pemphigoid is often made by a dermatologist, a healthcare provider who specializes in diseases affecting the skin.

A healthcare provider will ask for your medical history, including information about your recent symptoms and other medical conditions, which may provide important diagnostic clues. This information can also help rule out other possible causes of your symptoms. 

Your clinician will also perform a medical exam, with a special emphasis on the skin.

Additional tests are sometimes needed to make a diagnosis, however. Often this will involve taking a skin biopsy. By looking at biopsied skin tissue under a microscope, an expert can see characteristic signs of bullous pemphigoid. Blood tests, such as those for the antibodies to BP180 or BP230, are also often helpful.

Treatment

There is no cure for bullous pemphigoid. However, most people can get their disease under control with proper treatment that reduces itching, redness, and blister formation. To do this, healthcare providers will prescribe various medications that tamp down the person’s immune response. 

Corticosteroid creams are often prescribed as the initial treatment. Sometimes oral corticosteroids (like prednisone) are used instead. However, long-term use of steroids can lead to other health issues. If a person still has significant symptoms or if long-term use of steroids is causing problems, additional treatments are available. Some possibilities include:

• Imuran (azathioprine)
• CellCept (mycophenolate mofetil)
• Trexall (methotrexate)

Like corticosteroids, these are immunosuppressive drugs. Although they may be effective at reducing symptoms, they may also leave you more vulnerable to certain kinds of infections. 

People with bullous pemphigoid are at increased risk of death from infections than people of their age who don’t have the disease. This partly may be due to the use of immunosuppressive drugs.

Unfortunately, the symptoms of bullous pemphigoid often come back, even with proper treatment. If this happens, you might need to resume corticosteroids or try another type of immunosuppressant therapy.

Wound and Blister Care

Sometimes additional medications like antibiotics are needed to treat an infected, burst blister. Your healthcare provider can give you advice about daily care to help prevent infection, such as how to properly apply wound dressings for the location and severity of your blisters.

Additionally, to reduce the risk of irritating your skin, you may wish to wear loose-fitting clothing and limit certain physical activities until your blisters are under control. You may also need to eat soft foods for a while if you have any blisters on your mouth. And it's always wise to limit sun exposure to affected areas. 

A Word From Verywell

It can be alarming when the blisters of bullous pemphigoid appear, especially if you’ve never had such symptoms before. In some people, bullous pemphigoid can be a serious threat to overall health.  Fortunately, treatments are available to help keep the disease in check. Work with your healthcare team to find the best management options for you.