DH affects fewer people than typical coeliac diseaseA condition where a person is unable to eat gluten as it makes their body attack itself. at around one in 10,000 people. DH can appear at any age, but is most commonly diagnosed in those aged between 15 and 40 years. DH is rare in children.
Typical symptoms are:
- Red, raised patches, often with blisters that burst with scratching
- Severe itching and often stinging
The rash is seen most on the elbows, knees and buttocks, but any area of the skin can be affected. The rash is usually seen on both sides of the body, for example on both elbows.
How is DH diagnosed?
DH is diagnosed by a simple test called a skin biopsyA dermatologist takes a small sample of skin from an area that is unaffected by the DH. .
A dermatologistA doctor who specialises in skin conditions. takes a biopsy from an area without the rash. This is important because if the biopsy is taken from the area with the rash it doesn't always give the right result.
This skin sample is checked for antibodiesExist in the blood and are used by the immune system to attack viruses or bacteria. , known as Immunoglobulin A (IgA).
Anyone with a positive skin biopsy result should then be referred to a gastroenterologistA doctor who specialises in the digestive system. for a gut biopsyThis simple procedure looks for gut damage. A thin tube is passed through the mouth, down to the upper part of the small intestine. Then a tiny sample of gut lining is collected. This can be done using local anaesthetic and/or sedation. , which is the same test used in diagnosing coeliac disease.
It is essential that you keep eating glutenA protein that is found in the cereals wheat, barley and rye. until the gut biopsy has been carried out to guarantee an accurate result.
Even though people with DH may not complain of gut symptoms such as diarrhoea, constipation, stomach pain or bloating, most people do have the same kind of gut damage that is seen with coeliac disease.
How is it treated?
A gluten-freeWhen a food has less than 20 parts per million (ppm) of gluten so it is safe for people with coeliac disease to eat. diet is an essential long term part of the treatment for DH and the most long-term effective treatment.
The time it takes for the skin rash to improve varies between people. Skin symptoms tend to take longer to recover compared to typical gut symptoms associated with coeliac disease; in some cases it can take up to four years for the gluten-free diet to take effect.
Drug treatment can help control the rash in the early stages. The most common drug prescribed for this condition is Dapsone. This works within days, although skin symptoms will reappear if the drug is stopped before a gluten-free diet has taken effect.
It is important to find the lowest effective dose of the drug because there are side effects. The most common side effect is anaemia and your doctor may check for this on a regular basis. Less common side effects include headache, depression and damage to nerves, although this is rare.
DH should be monitored once the drug dose is reduced. Using medications such as Dapsone will not make the gut damage seen in DH worse.
For those who cannot tolerate Dapsone, there are two other drugs which also clear the rash - sulphapyridine and sulphamethoxypyridazine.
A gluten-free diet is, therefore, an essential part of the treatment of DH, as it is for anyone with coeliac disease.
Does dermatitis herpetiformis increase health risks?
The same complications occur in those with DH as in coeliac disease, which include osteoporosisA condition where your bones lose bone mass and become brittle. , certain kinds of gut cancer and an increased risk of other autoimmuneA reaction to a trigger which causes the body to attack itself. diseases such as thyroid disease. As in typical coeliac disease, the risk of developing these complications is reduced if the gluten-free diet is strictly followed.
Anyone medically diagnosed with DH can join Coeliac UK as a Member.