Skip to content

What Is Dermatitis Herpetiformis?#

Medical Disclaimer

This guide is for informational purposes only. It is not medical advice. Read the full disclaimer.

Dermatitis herpetiformis (DH) is the skin manifestation of celiac disease. If you have DH, you have celiac disease — even if you've never had digestive symptoms.

The short version#

When you eat gluten, your immune system produces antibodies that attack your own body. In celiac disease, these antibodies primarily damage the small intestine. In DH, a specific type of these antibodies (called IgA anti-TG3) deposits in the skin, causing an inflammatory reaction that results in intensely itchy blisters.

DH is not an allergy. It's an autoimmune disease driven by a genetic predisposition and triggered by gluten.

What's happening in your body#

Here's the chain of events, simplified:

  1. You eat gluten (a protein in wheat, barley, and rye)
  2. An enzyme called tissue transglutaminase (TG2) modifies the gluten in your gut
  3. Your immune system sees the modified gluten as a threat and produces antibodies
  4. Over time, some of these antibodies start targeting a related enzyme in your skin called TG3 (epidermal transglutaminase)
  5. IgA antibodies bind to TG3 in your skin, forming deposits in the upper layer of the dermis
  6. These deposits activate complement (part of your immune system) and recruit neutrophils (white blood cells)
  7. The neutrophils release enzymes that damage the skin, creating blisters and intense itching

This process explains several things patients find confusing:

  • Why there's a delay between eating gluten and getting a rash (days to weeks)
  • Why the rash takes so long to clear on a gluten-free diet (the IgA deposits can persist for years)
  • Why dapsone works so fast (it blocks the neutrophils, not the antibodies)

Full science: Pathogenesis & Immunology

What the rash looks and feels like#

DH has a characteristic pattern:

  • Where it appears: Elbows (~90% of patients), knees (~70%), buttocks (~60%), scalp, upper back, and shoulders. Usually symmetrical (both sides).
  • What it looks like: Small, grouped blisters and red bumps. Most people scratch them before a doctor ever sees intact blisters.
  • How it feels: Intensely itchy — often described as burning or stinging. The itch can be so severe it disrupts sleep and daily life. It frequently starts before you can see anything on the skin.

The rash tends to appear on extensor surfaces — areas where your skin stretches over joints. This may be because mechanical pressure activates the inflammatory process at those sites.

The celiac connection#

DH doesn't happen without celiac disease. Here's what the research shows:

  • Over 90% of DH patients have evidence of intestinal damage on biopsy, even if they have zero digestive symptoms
  • 15-25% of people with celiac disease eventually develop DH
  • DH typically appears years to decades after the onset of celiac disease (often undiagnosed)
  • Peak onset is in the 30s-40s
  • It's more common in men (1.5-2:1 ratio), which is unusual because celiac itself is more common in women

The reason DH develops late is a process called epitope spreading — your immune system gradually expands from attacking TG2 (in the gut) to also attacking TG3 (in the skin). This takes time.

Full science: Epidemiology & Diagnosis

Who gets DH?#

  • Genetics: Nearly all DH patients carry the HLA-DQ2 or HLA-DQ8 gene variants. These are necessary but not sufficient — about 30-40% of the general population carries them too.
  • Ethnicity: Most common in people of Northern European descent (Scandinavian, Irish, British). Rare in East Asian and Sub-Saharan African populations.
  • Prevalence: About 11-75 per 100,000 people, depending on the country. Finland has the highest rates.

Full science: Genetics & Genomics

Is it curable?#

DH is a chronic condition, but most patients achieve excellent control:

  • 40-70% of patients control their skin completely without medication after 2+ years on a strict gluten-free diet
  • 10-20% of patients eventually achieve spontaneous remission (can tolerate gluten again), though this is unpredictable
  • Overall mortality for DH patients is actually lower than the general population (likely due to healthier dietary patterns)

The gluten-free diet treats the root cause. Dapsone manages symptoms while the diet takes effect. Most patients use both initially, with the goal of eventually relying on diet alone.

Next steps#

Now that you understand what DH is, learn how to get properly diagnosed:

Getting Diagnosed