Dermatitis herpetiformis (DH) is an intensely itchy skin eruption. It usually shows up in young adults, and is more common in men and people originally from some areas of northern Europe. The symptoms are intense burning, stinging and itching around the elbows, knees, scalp, buttocks and back. More locations can also be affected and the severity can vary.
DH looks like small clusters of red, itchy bumps. There are tiny water blisters, but these are quickly scratched off. Before they form, the area usually has a burning feeling. They scab and heal over one or two weeks, but new spots continue to appear. DH is a lifelong condition, but remission may occur in 10 to 20 percent of patients.
Herpes virus does not cause DH, even though the name suggests that it does. The cause of DH is allergy to gluten, a protein found in wheat and some other grains. Usually allergies, likes hives and hay fever, are made by the body's IgE system. This can be treated with pills and shots. DH is different, and is an allergy of the IgA system. IgA is an antibody produced in the lining of the intestines. The usual allergy treatments are useless.
The rash is caused when gluten in the diet combines with IgA, and together they enter the blood stream and circulate. They eventually clog up the small blood vessels in the skin. This attracts white blood cells (neutrophils), and releases powerful chemicals called complements. They actually create the rash. Iodine is required for the reaction, so people with DH should avoid using Iodized salt.
The gut may also be affected by this allergy; this is called gluten-sensitive enteropathy (GSE) or celiac disease. Some people only have the GSE, some have GSE and DH and some just DH. It is not known why some develop on and not the other. There are cases of GSE that have turned cancerous (malignant lymphoma) so an evaluation by a gastroenterologist (a medical doctor specializing in the stomach and intestines) is prudent.
Diagnosis of DH usually requires at least one skin biopsy, and sometimes a blood test (looking for anti-gliadin, anti-reticulin and anti-endomysial antibodies). Once confirmed, treatment will be lifelong, although severity may wax and wane. Complete elimination of gluten is curative, but improvement takes months. The gluten-free diet is very difficult, as tiny amounts of gluten are in almost all restaurant and prepared foods, gum wrappers and the like. Cutting down on wheat and gluten may reduce the amount of medication needed, but will not be curative.
Fortunately, there is a very effective treatment. Dapsone is a drug that will improve DH in days. Because there can be side effects, the dose of Dapsone is usually started at a small amount, and then raised up over a few weeks until all symptoms are suppressed. Dapsone may have adverse effects, so weekly or bi-weekly blood tests will be needed for the first three months. There are a few alternative treatments if Dapsone cannot be used (sulfapyridine, tetracycline), however these do not work as well.
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