Causes of Dermatitis Herpetiformis
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.