What is dermatitis herpetiformis?
An itchy, blistering, burning skin rash, dermatitis herpetiformis (DH) is a difficult condition to live with. The rash and itching occur on the elbows, knees, scalp, back, and buttocks. This rash likely indicates gluten intolerance, which may be related to a more serious underlying condition known as celiac disease. DH is sometimes called Duhring’s disease or gluten rash. People who have this condition need to maintain a strict gluten-free diet.
From the sound of the name, many people think this rash is caused by some form of the herpes virus. This isn’t the case, as it has nothing to do with herpes. Dermatitis herpetiformis occurs in people with celiac disease. Celiac disease (also called celiac sprue, gluten intolerance, or gluten-sensitive enteropathy) is an autoimmune disorder characterized by intolerance to gluten. Gluten is a protein found in wheat, rye, and barley. It’s also sometimes found in oats that have been processed in plants that handle other grains.
According to the National Institutes of Health (NIH), 15 to 25 percent of people with celiac disease have DH. Celiac disease can also cause intense abdominal pain, constipation, nausea, and vomiting. People with DH typically don’t have any of the intestinal symptoms. However, even if they don’t experience any intestinal symptoms, 80 percent or more of people with DH still have intestinal damage, especially if they eat a diet that’s high in gluten, according to the National Foundation for Celiac Awareness (NFCA).
The intestinal damage and rash are due to the reaction of gluten proteins with a special kind of antibody called immunoglobulin A (IgA). Your body makes IgA antibodies to attack gluten proteins. When IgA antibodies attack gluten, they damage the parts of the intestines that allow you to absorb vitamins and nutrients. This sensitivity to gluten usually runs in families.
The structures formed when IgA attaches to gluten then enter the bloodstream, where they begin to clog small blood vessels, especially those in the skin. White blood cells are attracted to these clogs. The white blood cells release a chemical called “complement” that causes an itchy, blistery rash.
Celiac disease can affect anyone, but it tends to be more common in people who have another family member with celiac disease or DH.
Although more women than men are diagnosed with celiac disease, men are more likely to develop DH than women, according to the NIH. The rash usually begins in your 20s or 30s, though it can start in childhood. The condition more commonly occurs in people of European descent. It less commonly affects people of African or Asian descent.
DH is one of the itchiest rashes possible. Common locations of the rash include:
- lower back
- back of the neck
The rash is usually the same size and shape on both sides of the body and often comes and goes.
Before a full outbreak of the rash, you may feel the skin in a rash-prone area burn or itch. Bumps that look like pimples filled with clear liquid start to form. These are quickly scratched off. The bumps heal within a few days and leave a purple mark that lasts for weeks. But new bumps continue to form as old ones heal. This process can continue for years, or it can go into remission and then return.
While these symptoms are commonly associated with dermatitis herpetiformis, they can also be caused by other skin conditions such as atopic dermatitis, irritant or allergic contact dermatitis, psoriasis, pemphigoid, or scabies.
DH is best diagnosed with a skin biopsy. A doctor takes a small sample of skin and examines it under a microscope. Sometimes, a direct immunofluorescence test is done, in which the skin around the rash is stained with a dye that will show the presence of IgA antibody deposits. The skin biopsy can also help determine if the symptoms are caused by another skin condition.
Blood tests to check for these antibodies in the blood may also be done. An intestinal biopsy may be performed to confirm the presence of damage due to celiac disease.
If the diagnosis is uncertain, or another diagnosis is possible, other tests may be performed. Patch testing is the best way to diagnose allergic contact dermatitis, which is a common cause of symptoms similar to dermatitis herpetiformis.
DH can be treated with an antibiotic called dapsone. Dapsone is a powerful medicine with serious side effects. The dose must be increased slowly over several months before it’s fully effective.
Most people see relief from taking dapsone, but side effects may include:
Dapsone may also have negative interactions with other medications, such as aminobenzoate potassium, clofazimine, or trimethoprim.
Other drugs that may be used include tetracycline, sulfapyridine, and some immunosuppressive drugs. These are less effective than dapsone.
The most effective treatment that’s free of side effects is strict adherence to a gluten-free diet. This means you should completely avoid food, drink, or medicines containing the following:
Although this diet can be difficult to follow, it will have the most beneficial effect on your health if you have celiac disease. Any reduction in gluten intake may help lessen the amount of medication you will need to take.
People with untreated DH and celiac disease may have a higher risk of intestinal cancer due to the constant inflammation in the intestines. Vitamin deficiencies and anemia may also be a problem if the intestines aren’t absorbing nutrients properly.
Since DH is an autoimmune disease,
- type 1 diabetes mellitus
- myasthenia gravis
- Sjögren’s syndrome
- rheumatoid arthritis
DH is a lifelong disease. You may go into remission, but any time you’re exposed to gluten, you may have an outbreak of the rash. Without treatment, DH and celiac disease can result in many negative health effects, including vitamin deficiencies, anemia, and gastrointestinal cancer.
Treatment with dapsone can control the rash symptoms rather quickly. However, the intestinal damage caused by celiac disease can only be treated by maintaining a strict gluten-free diet. Make sure to discuss any specific dietary considerations with your doctor or nutritionist.