Causes and Treatment of Interface Dermatitis

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An interface dermatitis reaction, also known as auto-eczematization, is an itchy rash with small, water-filled blisters that is caused in response to a primary infection, usually fungal. It most often occurs on the sides of the fingers but can also be found on the chest or arms.

Interface dermatitis is not one disease with a single cause but one that occurs in a specific area in the skin, namely in the dermo-epidermal junction between the outermost layer of skin (epidermis) and the middle layer (dermis).


An ID reaction can vary in appearance from one person to the next because the underlying cause can differ. But it typically involves some or all of the following features:

  • Localized or widespread vesicular lesions (small, fluid-filled spots)
  • Red patches with raised red bumps (maculopapular or scarlatiniform eruptions)
  • Deep, raised, bruise-like areas on the shins (erythema nodosum)

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erythema nodosum
Erythema nodosum on the legs. DermNet / CC BY-NC-ND
  • Pinkish red spots that resemble targets (erythema multiforme)

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erythema multiforme
Erythema multiforme of the hands.  DermNet / CC BY-NC-ND
  • Light pink teardrop-shaped bumps (guttate psoriasis)

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Guttate psoriasis
Guttate psoriasis on the back. DermNet / CC BY-NC-ND


The most common cause of ID reactions is a fungal infection somewhere else on the body, especially athlete's foot. It can also occur as a result of a bacterial, viral, or parasitic infection.

Interface dermatitis is also typically seen with autoimmune skin disorders such as lichen planus or cutaneous lupus erythematosus. Similarly, it can occur as a result of an immune response to viruses, tumors, or even drugs.

Dermatomyositis, erythema multiforme, drug eruptions, and pityriasis lichenoides are other major interface diseases. Several other diseases (inflammatory, infectious, and cancerous) may show interface changes.

Diagnosis and Treatment

Treating an ID reaction depends largely on what caused it in the first place. Your dermatologist will want to identify the underlying infection and/or conditions that spurred the response. This is usually done by taking scrapings from the affected area.

Other tests can include:

  • Skin culture for bacteria, fungus, or virus
  • Allergy skin testing to rule out contact dermatitis
  • A skin biopsy usually performed to confirm a diagnosis

As ID reactions are thought to be an allergic response to fungi or other pathogens, treatment of the underlying infection will typically resolve the rash.

In some cases, an ID reaction may be the only way a person knows that he or she has an infection that needs to be treated. To relieve symptoms, your doctor may prescribe a corticosteroid cream or oral anti-itch medication. Antihistamines may be prescribed in cases of an allergic response.

Common Infections That Can Cause Interface Dermatitis

While an ID reaction may occur as a result of any number of reasons, the more common causes include:

  • Ringworm (tinea corporis or tinea capitis), a common fungal infection
  • Athlete's foot (tinea pedis)
  • Jock itch (tinea cruris)
  • Spider bites
  • Tinea versicolor, an overgrowth of yeast common in subtropical regions
  • Intertrigo, a yeast infection of skin folds caused by the fungi Candida albicans

While an ID reaction rash cannot be passed from one person to the next, the primary condition that gave rise to the reaction may be contagious.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Joshi R. Interface dermatitis. Indian J Dermatol Venereol Leprol. 2013;79(3):349-59. doi:10.4103/0378-6323.110780

  2. Alsaad KO, Ghazarian D. My approach to superficial inflammatory dermatoses. J Clin Pathol. 2005;58(12):1233-41. doi:10.1136/jcp.2005.027151

Additional Reading
  • Lowther C.; Miedler, J.; Cockerell, C.; et al. “Id-like reaction to BCG therapy for bladder cancer.” Cutis. March 2013; 91(3):145-151.

  • Wenzel, J., and Tüting, T. “An IFN-associated cytotoxic cellular immune response against viral, self-, or tumor antigens is a common pathogenetic feature in "interface dermatitis." J Invest Dermatol. Oct 2008; 128(10):2392-2402. 

  • Ilkit, M; Durdu, M.; and Karakaş, M. “Cutaneous id reactions: a comprehensive review of clinical manifestations, epidemiology, etiology, and management.' Crit Rev Microbiol. August 2012; 38(3):191-202.