Dermatitis herpetiformis (DH) is the skin manifestation of the body's abnormal response to gluten. It often occurs with coeliac disease, but can occur alone without bowel damage. DH affects around 1 in 10,000 people. It can appear at any age, but is most common in people in their thirties. It is more common in men than women.
How is dermatitis herpetiformis diagnosed
Diagnosis is confirmed by a simple skin test called a skin biopsy. A dermatologist (skin specialist) takes a small sample of skin from an area near to the skin affected by the rash. This is then checked for the presence of an antibody called immunoglobulin A (lgA). If the antibody is found, this means the skin biopsy is positive and you should be referred to a gastroenterologist (gut specialist) for further testing. This testing includes coeliac disease antibody tests and often includes a small bowel biopsy. Even though you may not have any gut symptoms, you may have the gut damage associated with coeliac disease. Other tests may look for associated problems, such as thyroid disease. To make sure you get an accurate test result first time, it is important to keep eating gluten until you have the antibody blood tests and biopsy. If you have already taken gluten out of your diet, this will need to be re-introduced for at least 6 weeks before you have the tests. Your GP will clarify the time frame, and the amount of gluten you need to consume.
- A rash that most commonly occurs on the elbows, knees, shoulders, buttocks and face but it can affect any area of the body
- The rash usually occurs symmetrically on the body, for example on both elbows.
- Red, raised patches, often with blisters that burst with scratching.
- Severe itching, burning and often stinging.
How is it treated
The treatment for DH is a life-long gluten free diet. This means you will have to remove all sources of gluten – the protein found in wheat, rye, barley
and oats – from your diet. Although a gluten free diet is the effective treatment in the long term, it can take an average of two years for it to take
full effect, so you may also need drug treatment to begin with.
The most commonly prescribed drug for DH is Dapsone. This will help control the itching and development of blisters, although the rash will come back if you stop taking it before the gluten free diet has taken effect. Side effects are common so it is important to find the lowest effective dose of Dapsone, which your GP or specialist will help with. The side effects of Dapsone can include anaemia, headaches, depression and nerve damage, although this is rare.
Dapsone will only help control the skin itching and blisters and will not treat any other areas: it is not a substitute for a gluten free diet, which is an essential part of treatment for DH.
Does this condition increase the risk of other diseases?
As with coeliac disease, DH is also associated with an increased risk of other autoimmune diseases such as thyroid disease or Type 1 diabetes. The complications that occur in coeliac disease can also occur in DH: these include osteoporosis and certain types of small bowel cancer. Once you have been following the gluten free diet for some time, the risk of osteoporosis is reduced and the risk of cancer becomes the same as someone who doesn’t have coeliac disease or dermatitis herpetiformis.
This information is for guidance only and should not replace advice given by your medical professional