Contact Dermatitis

Contact dermatitis is an inflammatory skin reaction that occurs when the skin is directly exposed to substances that either irritate the skin barrier (irritant contact dermatitis, ICD) or trigger an immune-mediated allergy (allergic contact dermatitis, ACD). It presents with itching, redness, swelling, and sometimes blisters or scaling at sites of contact. The condition is not contagious. Common triggers include soaps and detergents, solvents, rubber accelerators, nickel in jewelry, fragrances, preservatives, and plants such as poison ivy. In everyday practice, ICD is more common than ACD, while both forms can look similar clinically.

Types and Key Features

• Irritant contact dermatitis results from direct damage to the stratum corneum by physical or chemical agents; it can occur in anyone and often follows repeated or prolonged exposure (“wet work,” detergents, or friction). Symptoms such as burning or stinging may appear soon after exposure and improve once the irritant is removed.

• Allergic contact dermatitis is a delayed (type IV) T‑cell–mediated hypersensitivity to small chemicals (haptens) after prior sensitization. On re‑exposure, a rash typically appears 24–72 hours later, peaks around 72–96 hours, and may recur rapidly with subsequent contacts. Frequent allergens include nickel, isothiazolinone preservatives, fragrance components, and topical medications. A photoallergic variant arises when a chemical becomes allergenic in the presence of ultraviolet light.

Diagnosis

Diagnosis relies on a careful exposure history and physical examination, looking for patterns that map to specific products, tasks, or materials (for example, peri‑umbilical rash from a belt buckle suggests nickel). Patch testing is the reference standard to confirm ACD and to identify culprit allergens; standardized panels are applied to the back for 48 hours with readings over several days. Population patch‑test data in North America consistently highlight nickel, isothiazolinones, and fragrance components among the most frequent positives.

Treatment and Management

The cornerstone of management is avoidance of the offending irritant or allergen. For symptom control, topical corticosteroids are first‑line for inflamed areas, supported by emollients to restore barrier function; short courses of systemic corticosteroids may be used for severe, widespread flares. Nonsteroidal topical calcineurin inhibitors (tacrolimus, pimecrolimus) can be useful on sensitive sites or for steroid‑sparing maintenance. Education on reading ingredient labels and substituting products free of the identified allergen is critical to preventing recurrences.

Prevention and Importance

Contact dermatitis is common and burdensome, affecting an estimated 15%–20% of people and contributing substantially to healthcare visits and lost productivity. Occupationally, it represents the majority of reported work‑related skin diseases in the United States; risk is highest in jobs with frequent water, chemical, or glove exposure (for example, healthcare, cleaning, food service, hairdressing, and manufacturing). Preventive strategies include minimizing “wet work,” substituting less irritating products, using appropriate gloves, moisturizing regularly, and instituting workplace dermal‑exposure controls.

Why It Matters

Beyond discomfort, contact dermatitis can become chronic, disrupt sleep and work, and predispose to secondary infection. Accurate identification of triggers—often via patch testing—enables targeted avoidance, reduces flares, and can meaningfully improve quality of life at home and at work.

Sources

• Mayo Clinic. Contact dermatitis – Symptoms and causes. https://www.mayoclinic.org/health/contact-dermatitis/DS00985

• Mayo Clinic. Contact dermatitis – Diagnosis and treatment. https://www.mayoclinic.org/diseases-conditions/contact-dermatitis/diagnosis-treatment/drc-20352748

• American Academy of Allergy, Asthma & Immunology (AAAAI). Contact Dermatitis Overview. https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/contact-dermatitis-overview

• CDC/NIOSH. About Skin Exposures and Effects – Contact Dermatitis. https://www.cdc.gov/niosh/skin-exposure/about/index.html

• StatPearls (NCBI Bookshelf). Contact Dermatitis. https://www.ncbi.nlm.nih.gov/sites/books/NBK459230/

• Journal of Allergy and Clinical Immunology: In Practice. Recognizing and Managing Allergic Contact Dermatitis: Focus on Major Allergens (2024). https://www.sciencedirect.com/science/article/abs/pii/S2213219824005257

• North American Contact Dermatitis Group Patch Test Results: 2021–2022. https://pubmed.ncbi.nlm.nih.gov/40274377/

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