What is dermatitis herpetiformis? How does it differ from herpes? What are the causes, symptoms, and diagnosis of this condition? Find out the answers to these questions and more.

Understanding Dermatitis Herpetiformis

Dermatitis herpetiformis (DH) is a chronic, autoimmune skin condition that causes an intensely itchy, blistering rash. Contrary to its name, DH is not caused by the herpes virus, but rather is closely linked to celiac disease, an autoimmune disorder characterized by intolerance to gluten. In fact, 15 to 25 percent of people with celiac disease also develop DH, according to the National Institutes of Health (NIH).

Causes of Dermatitis Herpetiformis

The underlying cause of DH is an abnormal immune response to gluten. When someone with DH ingests gluten, their body produces immunoglobulin A (IgA) antibodies to attack the gluten proteins. These antibodies then circulate in the bloodstream and become trapped in small blood vessels, particularly in the skin. This triggers an inflammatory response, leading to the characteristic itchy, blistering rash.

Celiac disease and DH often run in families, suggesting a genetic component. Men are also more likely to develop DH than women, according to the NIH.

Symptoms of Dermatitis Herpetiformis

The primary symptom of DH is a severely itchy, blistering rash that typically appears on the elbows, knees, scalp, back, and buttocks. The rash is usually symmetrical, meaning it appears on both sides of the body. Before the rash fully develops, the affected skin may burn or itch.

The rash itself consists of small, fluid-filled bumps that quickly rupture, leaving behind red, raw areas that crust over. New bumps continue to form as older ones heal, perpetuating the cycle. This process can go on for years, with periods of remission and relapse.

It’s important to note that the symptoms of DH can be similar to other skin conditions, such as atopic dermatitis, contact dermatitis, and psoriasis. This can make diagnosis challenging.

Diagnosing Dermatitis Herpetiformis

To diagnose DH, healthcare providers typically perform a skin biopsy. During this procedure, a small sample of the affected skin is removed and examined under a microscope to look for the characteristic IgA deposits. A direct immunofluorescence test may also be used to identify these antibodies.

Blood tests to check for celiac disease-related antibodies may also be ordered, as the two conditions are closely linked. In some cases, an intestinal biopsy may be performed to confirm the presence of celiac disease-related damage.

If the diagnosis is unclear, additional testing, such as patch testing, may be done to rule out other skin conditions with similar symptoms.

Treatment for Dermatitis Herpetiformis

The primary treatment for DH is a strict, lifelong gluten-free diet. This helps control the immune system’s response to gluten and can lead to a reduction in symptoms. However, the rash and itching may persist for some time even after adopting a gluten-free diet.

In addition to dietary changes, healthcare providers may prescribe the antibiotic dapsone to help manage the symptoms of DH. Dapsone is a powerful medication with potential side effects, so it must be introduced gradually and closely monitored.

For some individuals, the rash and itching may go into remission, only to return at a later time. Maintaining a gluten-free diet and working closely with a healthcare provider is crucial for managing the condition long-term.

Preventing Complications

While DH primarily affects the skin, the underlying celiac disease can also cause damage to the intestines and lead to nutrient deficiencies. Therefore, it’s important for individuals with DH to adhere to a strict gluten-free diet to prevent complications such as malnutrition, osteoporosis, and an increased risk of certain types of cancer.

Regular check-ups with a healthcare provider, as well as monitoring for any changes in symptoms or overall health, are also essential for managing DH and its associated conditions.

Seeking Professional Help

If you suspect you may be experiencing symptoms of dermatitis herpetiformis, it’s important to seek medical attention. A dermatologist or other healthcare provider can properly diagnose the condition and develop an appropriate treatment plan. With the right care and lifestyle modifications, individuals with DH can effectively manage their symptoms and reduce the risk of complications.

Dermatitis Herpetiformis: Causes, Symptoms, and Diagnosis

What is dermatitis herpetiformis?

An itchy, blistering, burning skin rash, dermatitis herpetiformis (DH) is a difficult condition to live with. The rash and itching occur on the elbows, knees, scalp, back, and buttocks. This rash likely indicates gluten intolerance, which may be related to a more serious underlying condition known as celiac disease. DH is sometimes called Duhring’s disease or gluten rash. People who have this condition need to maintain a strict gluten-free diet.

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.

Celiac disease can affect anyone, but it tends to be more common in people who have another family member with celiac disease or DH.

Although more women than men are diagnosed with celiac disease, men are more likely to develop DH than women, according to the NIH. The rash usually begins in your 20s or 30s, though it can start in childhood. The condition more commonly occurs in people of European descent. It less commonly affects people of African or Asian descent.

DH is one of the itchiest rashes possible. Common locations of the rash include:

• elbows
• knees
• lower back
• hairline
• back of the neck
• shoulders
• buttocks
• scalp

The rash is usually the same size and shape on both sides of the body and often comes and goes.

Before a full outbreak of the rash, you may feel the skin in a rash-prone area burn or itch. Bumps that look like pimples filled with clear liquid start to form. These are quickly scratched off. The bumps heal within a few days and leave a purple mark that lasts for weeks. But new bumps continue to form as old ones heal. This process can continue for years, or it can go into remission and then return.

While these symptoms are commonly associated with dermatitis herpetiformis, they can also be caused by other skin conditions such as atopic dermatitis, irritant or allergic contact dermatitis, psoriasis, pemphigoid, or scabies.

DH is best diagnosed with a skin biopsy. A doctor takes a small sample of skin and examines it under a microscope. Sometimes, a direct immunofluorescence test is done, in which the skin around the rash is stained with a dye that will show the presence of IgA antibody deposits. The skin biopsy can also help determine if the symptoms are caused by another skin condition.

Blood tests to check for these antibodies in the blood may also be done. An intestinal biopsy may be performed to confirm the presence of damage due to celiac disease.

If the diagnosis is uncertain, or another diagnosis is possible, other tests may be performed. Patch testing is the best way to diagnose allergic contact dermatitis, which is a common cause of symptoms similar to dermatitis herpetiformis.

If you don’t already have a dermatologist, you can browse doctors in your area through the Healthline FindCare tool.

DH can be treated with an antibiotic called dapsone. Dapsone is a powerful medicine with serious side effects. The dose must be increased slowly over several months before it’s fully effective.

Most people see relief from taking dapsone, but side effects may include:

• liver problems
• sensitivity to sunlight
• anemia
• muscle weakness
• peripheral neuropathy

Dapsone may also have negative interactions with other medications, such as aminobenzoate potassium, clofazimine, or trimethoprim.

Other drugs that may be used include tetracycline, sulfapyridine, and some immunosuppressive drugs. These are less effective than dapsone.

The most effective treatment that’s free of side effects is strict adherence to a gluten-free diet. This means you should completely avoid food, drink, or medicines containing the following:

• wheat
• rye
• barley
• oats

Although this diet can be difficult to follow, it will have the most beneficial effect on your health if you have celiac disease. Any reduction in gluten intake may help lessen the amount of medication you will need to take.

People with untreated DH and celiac disease may have a higher risk of intestinal cancer due to the constant inflammation in the intestines. Vitamin deficiencies and anemia may also be a problem if the intestines aren’t absorbing nutrients properly.

Since DH is an autoimmune disease, researchers have found that it’s also associated with various other types of autoimmune diseases. These include:

• hypothyroidism
• vitiligo
• type 1 diabetes mellitus
• myasthenia gravis
• Sjögren’s syndrome
• rheumatoid arthritis

DH is a lifelong disease. You may go into remission, but any time you’re exposed to gluten, you may have an outbreak of the rash. Without treatment, DH and celiac disease can result in many negative health effects, including vitamin deficiencies, anemia, and gastrointestinal cancer.

Treatment with dapsone can control the rash symptoms rather quickly. However, the intestinal damage caused by celiac disease can only be treated by maintaining a strict gluten-free diet. Make sure to discuss any specific dietary considerations with your doctor or nutritionist.

Allergic Contact Dermatitis > Fact Sheets > Yale Medicine

Overview

There are many types of rashes, including those caused by toxins (such as poison ivy) or illnesses (such as roseola or chicken pox). If you get a red, itchy rash with no known cause, it could be allergic contact dermatitis.  

This itchy skin rash can result from exposure to a chemical or compound that causes a response from the skin’s immune system. The rash will arise at the point of contact with the allergen. The area is usually a pink or red color and feels itchy. Contact dermatitis may appear flat or raised, and in severe cases, blisters filled with clear fluid may result.

Although some people react more quickly than others, these rashes tend to take time to develop and don’t occur with the first exposure. 

“Allergic contact dermatitis is something that’s what we call a delayed type hypersensitivity,” says Keith Choate, MD, PhD, a Yale Medicine dermatologist. “Someone will be, for example, exposed in the garden on Sunday, and then start noticing that they have an eruption on Monday. So it’s not instantaneous. It takes time.”

Yale Medicine dermatologists have highly specialized expertise in treating complex skin disorders, including skin testing to determine the specific cause of a person’s allergic contact dermatitis. “Our physicians are really dedicated to getting answers,” Dr. Choate says.

What causes allergic contact dermatitis?

Allergic contact dermatitis can be caused by a wide variety of allergens and requires a minimum of two separate exposures. The first exposure sensitizes the person to the agent in question, while the second exposure brings on the rash.

According to Dr. Choate, allergic contact dermatitis is a condition that causes progressively more serious reactions. “It typically can worsen over time. The initial rash may be relatively mild,” he says. “And each subsequent time you’re exposed, it can actually get worse and worse until it reaches a maximum severity.”

Are there different kinds of allergic contact dermatitis?

There aren’t different kinds of allergic contact dermatitis, but there are many different allergens that can cause the condition. These allergens can be obvious, like poison ivy, or more subtle, like preservatives in personal care products, leather dyes or spandex.  

Allergic contact dermatitis needs to be distinguished from irritant contact dermatitis, rashes that are usually caused by repeated exposure to soaps, detergents or industrial chemicals. People can have both irritant and allergic contact dermatitis. If you have atopic dermatitis (eczema), your skin is more sensitive and susceptible to irritant reactions from a variety of exposures.

How is allergic contact dermatitis diagnosed?

Typically a diagnosis of allergic contact dermatitis is made by a dermatologist. Often the shape of the rash will determine the diagnosis. Rashes caused by external factors such as allergens or irritants are usually asymmetrical, and those caused by internal factors—such as atopic dermatitis—are often symmetrical, meaning that they occur in both sides of the body, for example, on both arms or legs. 

But a successful allergic contact dermatitis diagnosis doesn’t always indicate what caused the reaction in the first place. If someone hasn’t been exposed to a known allergen such as poison oak, it’s necessary to perform patch testing to determine the cause. 

Patch testing involves the application of square patches that are impregnated with a variety of different allergens—typically 36 of the most common ones. The patches need to remain on the patient’s skin for about 48 hours to ensure that the skin has time to react to the allergens. Once the patches are removed, it will typically take another 24 to 36 hours for a rash to appear.

Common allergens used in patch testing might include: nickel, fragrances, potassium dichromate (a metal used in tanning leather), neomycin (an ingredient in topical antibiotics) and formaldehyde-releasing preservatives often found in shampoo and other personal-care products.

Patch testing can be extremely helpful in determining the cause of the dermatitis and equipping patients with the tools to prevent these kinds of reactions in the future. “For people who have this ongoing dermatitis that’s showing up in a pattern that points to contact dermatitis, the patch test will frequently give us a result,” Dr. Choate says. “It’s very helpful in terms of figuring out what to do next.”

How is allergic contact dermatitis treated?

Allergic contact dermatitis is best treated by identifying and avoiding the allergen(s) that you are sensitized to. 

For symptom relief, applying a hydrocortisone cream and taking an antihistamine can help stop itching. Your doctor may prescribe topical steroids, and if the condition is widespread and more severe, it can be treated with systemic steroids such as Prednisone, which doctors will sometimes prescribe to ensure that the condition is fully treated. It can take a week to 10 days for the rash to resolve, but patients should experience relief from itchiness shortly after treatment begins.

Fully evaluating allergic contact dermatitis through patch testing, especially when it’s recurrent, can provide a patient with substantial quality of life improvements. According to Dr. Choate, “The minute that you figure out what’s causing reactions, you can have patients modify their lifestyles and everything goes away. It’s really remarkable.”

What are the risk factors for contact dermatitis?

Because so many things can ignite irritant or allergic reactions, contact dermatitis isn’t associated with specific, easily identifiable risk factors. But people who spend a lot of time outdoors or who work in an industrial setting are likely to experience this skin condition. 

“I think contact dermatitis happens for most weekend warriors out there who like to go into the mountains and go into their gardens and spend their time outdoors,” says Dr. Choate. 

It also can occur in people who work in industrial settings. Many compounds used in industrial materials such as cement and rubber can be allergens. “There are literally hundreds of things that people can have irritant or allergic reactions to,” Dr. Choate says.

Can a tolerance for a certain allergen change over time?

A person’s ability to develop an allergic response is thought to be determined by genetic factors and the frequency and intensity of exposure to the allergen. The potency of the allergen is another critical factor. Generally, once a person develops an allergy, the sensitivity to that chemical is lifelong.

The integrity of the skin barrier is considered to be an important element in the sensitization process. Allergens, which are small molecules that can pass through most gloves, are more likely absorbed through damaged skin. In this way, people who have irritant contact dermatitis (e.g. from frequent hand washing) may be more likely to develop an allergy to substances that they’re exposed to (e.g. chemical preservative in a skin moisturizer).

Under those circumstances, it makes sense that people who develop allergic contact dermatitis based on a new allergy might mistake it for another kind of skin condition such as chronically dry skin, says Dr. Choate.

What is Yale Medicine’s approach to treating allergic contact dermatitis?

According to Dr. Choate, one thing that sets Yale Medicine dermatologists apart is their willingness to aggressively pursue results.