Dermatitis herpetiformis

Dermatitis herpetiformis (DH) is an autoimmune skin condition, and it can be linked to coeliac disease.

Dermatitis herpetiformis (DH) is not common. It affects around 1 in 10,000 people.

It can appear at any age, but doctors most often diagnose it in people between the ages of 15 and 40. Men are affected more than women, and it is rare in children.

People with dermatitis herpetiformis (DH) can have:

• red, raised patches, often with blisters that burst when scratched
• severe itching, and often stinging

The rash can appear on any area of the skin, but it's most commonly seen on the:

• elbows
• knees
• buttocks

It usually shows up on both sides of the body, for example on both elbows.

Most people with dermatitis herpetiformis (DH) have the same kind of gut damage that is seen with coeliac disease, but they may not complain of gut symptoms such as:

• diarrhoea
• constipation
• stomach pain
• bloating

In fact, just over half (60%) of people with DH don't have any gut symptoms.

Dermatitis herpetiformis (DH) happens when the body's immune system reacts to gluten, a protein found in foods that contain wheat, barley and rye. This reaction is what brings on the skin rash.

Doctors confirm dermatitis herpetiformis (DH) with a skin test called a skin biopsy. This is a procedure where a small sample of skin is removed so it can be tested.

DH is strongly linked to coeliac disease, so you may also have blood tests for that condition.

In a skin biopsy for dermatitis herpetiformis (DH), a skin specialist called a dermatologist takes a small sample of skin from an area without the rash. Samples taken from the rash itself don't always give an accurate result.

The sample is then tested. If the result is positive for DH, you'll be referred to a specialist gut doctor called a gastroenterologist, who will test you for coeliac disease.

Keep eating foods that contain gluten before and during your diagnosis of dermatitis herpetiformis. That way the skin test is more likely to be accurate the first time.

If you've already taken gluten out of your diet, you must bring it back in more than one meal every day. Do this for at least 6 weeks before you have the tests.

The treatment for dermatitis herpetiformis (DH) is a gluten-free diet, and you need to follow it for life.

On a gluten-free diet, you remove every food that contains gluten. Gluten is found in wheat, barley and rye, and some people are sensitive to oats too.

Don't start the diet on your own. Wait until your doctor has confirmed the diagnosis of DH and you have been referred to a dietitian.

How long the skin takes to heal differs from one person to another. With dermatitis herpetiformis, it can take up to 2 years or more.

Some people with dermatitis herpetiformis are given medicine to help them through the recovery period. It only controls the itching and the blisters on the skin, and it doesn't treat any other symptoms. The medicine most likely to be used is called Dapsone.

You take Dapsone as a tablet, and you need to swallow it. It eases the itching and keeps blisters from developing, and it should start working within a few days. Don't stop taking Dapsone before the gluten-free diet has taken effect, because the rash will come back if you do.

Anaemia is the most common side effect of Dapsone, the medicine used to treat dermatitis herpetiformis (DH). Headaches and depression are less common, and nerve damage is rare.

To help prevent these side effects, you'll always be given the lowest dose that works. Once the dose has been reduced, your DH should be monitored.

Some people can't tolerate Dapsone. If you're one of them, you can take one of these medicines instead to clear the rash:

• Sulphapyridine
• Sulphamethoxypyridazine

Dermatitis herpetiformis (DH) can cause the same conditions and complications as coeliac disease. Some of the complications you may face with DH include:

• osteoporosis
• certain kinds of gut cancer
• an increased risk of other autoimmune diseases, such as type 1 diabetes and thyroid disease

As with coeliac disease, following a gluten-free diet reduces your risk of developing these.