Triggers to Know#
Medical Disclaimer
This guide is for informational purposes only. It is not medical advice. Read the full disclaimer.
Gluten is the primary trigger for DH, but it's not the only factor that can cause or worsen flares. Understanding these other triggers can help if your rash persists despite a strict gluten-free diet.
Iodine#
Iodine is the best-documented non-gluten trigger for DH. The connection dates to 1891, and potassium iodide was historically used as a diagnostic test.
How it works#
Iodine appears to increase TG3 enzyme activity in the skin — the same enzyme targeted by the IgA antibodies that cause DH. In patients with existing IgA deposits, excess dietary iodine can amplify the inflammatory reaction without any gluten being involved.
High-iodine foods to watch#
| Food | Iodine content | Risk level for DH |
|---|---|---|
| Kelp / seaweed | Extremely high (up to 2,000+ mcg per serving) | Avoid during active disease |
| Iodized salt | 77 mcg per 1/4 tsp | Switch to non-iodized salt during active disease |
| Shellfish (lobster, shrimp) | 100-200+ mcg per serving | Moderate; reduce if flaring |
| Cod | ~100 mcg per 3 oz | Moderate |
| Dairy | 50-90 mcg per cup | Generally tolerated at normal intake |
| Eggs | ~25 mcg per egg | Low risk at normal intake |
| Salmon, sardines | Low (10-15 mcg per serving) | Safe at all disease stages |
When to restrict iodine#
- During active flares that persist despite strict GFD: reduce high-iodine foods
- Once your rash clears on GFD: iodine restriction is generally no longer necessary
- Do not eliminate iodine entirely — it's essential for thyroid function. Restrict only the highest sources during active disease.
- Always avoid kelp/seaweed supplements and iodine supplements during active DH
Full analysis: Iodine Deep Dive
Alcohol#
Alcohol interacts with DH through three separate mechanisms:
1. Induces gluten sensitization#
A study of 904 patients found that 44% of heavy alcohol users developed antigliadin antibodies (vs. 12% of controls). Alcohol damages the intestinal lining, allowing gluten to cross the gut barrier more easily.
2. Triggers anti-TG2 IgA responses#
Alcohol can independently activate the same autoimmune pathway that drives DH — even without gluten exposure.
3. Increases gut permeability#
Even moderate drinking (1-2 drinks/day) worsens intestinal permeability, amplifying the immune response to any gluten you do encounter.
Practical guidance#
| Beverage | Risk | Reason |
|---|---|---|
| Beer (standard) | High | Contains barley-derived gluten + alcohol effects |
| "Gluten-reduced" beer | Risky | May retain immunotoxic gluten fragments |
| Wine | Lower (gluten-free) | No gluten, but alcohol still affects gut permeability |
| Distilled spirits | Lower (gluten-free) | Distillation removes proteins, but alcohol effects remain |
Beer is a double hit — gluten exposure plus barrier disruption. Even gluten-free alcoholic beverages still compromise gut permeability. If your DH is poorly controlled, consider reducing or eliminating alcohol.
Full science: Pathogenesis & Immunology, Section 20
NSAIDs#
Aspirin, ibuprofen, naproxen, and other non-steroidal anti-inflammatory drugs (NSAIDs) are documented DH triggers. The mechanism isn't fully understood, but the clinical association is well-established.
- Patients report lesion breakouts when using NSAIDs
- The combination of NSAIDs + dapsone may be particularly problematic
- Alternative pain relievers: Acetaminophen (Tylenol) does not appear to trigger DH
If you need anti-inflammatory medication regularly, discuss alternatives with your doctor.
Stress#
Stress is frequently reported by patients as a flare trigger or amplifier. The mechanism likely involves:
- Stress hormones modulating immune function
- Reduced immune regulation (lower Treg activity)
- Changes in gut permeability under stress
Stress probably doesn't cause flares directly but lowers the threshold — making you more reactive to small gluten exposures or other triggers.
Physical factors#
Heat and sweating#
Some patients report worsening in summer or after exercise. Heat and sweat at skin friction sites (under boots, tight clothing, bra straps) may aggravate the inflammatory process.
Mechanical pressure (Koebner phenomenon)#
DH lesions preferentially appear at sites of mechanical stress — elbows, knees, buttocks, belt lines, under tight clothing. This is likely because pressure activates TG3 enzyme activity and triggers neutrophil recruitment at those sites.
Practical tips:
- Avoid tight, restrictive clothing over common DH sites
- Be aware that new friction areas (a new watch band, different shoes) may develop lesions
- Shower promptly after heavy sweating
Vitamin D deficiency#
While not a trigger per se, vitamin D deficiency is extremely common in DH/celiac patients (due to intestinal malabsorption) and may impair immune regulation:
- Vitamin D promotes regulatory T-cells (Tregs) that help control the autoimmune response
- It supports intestinal barrier function
- Deficiency may prolong the time to disease control
Get your levels tested. Target 40-60 ng/mL of 25-OH vitamin D. Most DH patients need supplementation.
Hormonal factors#
Some women report premenstrual flare patterns. The progesterone peak 3-4 days before menstruation can trigger skin inflammation broadly. This is under-studied in DH specifically, but the patient reports are consistent.
Summary: what to do if the rash persists on strict GFD#
If you're strictly gluten-free and still flaring, work through this checklist:
- Audit for hidden gluten — cross-contamination is the most common cause
- Reduce high-iodine foods — especially kelp, seaweed, iodized salt
- Stop NSAIDs — switch to acetaminophen
- Reduce or eliminate alcohol — especially beer
- Give it time — it can take 2+ years for GFD alone to control the rash
- Check vitamin D levels — supplement if deficient
- Manage stress — not a cure, but removes an amplifying factor
- Talk to your doctor — about adjusting dapsone or investigating other causes
Full trigger science: Cross-Reactivity & Triggers
Next steps#
Learn which tests to track as your treatment progresses: