Allergic contact dermatitis is a type of eczema caused by an immune reaction after the skin touches a substance to which it has become sensitive. It is different from irritant contact dermatitis, which results from direct damage by substances such as soaps, detergents or solvents.
Symptoms
The affected skin may become itchy, red or darker than the surrounding skin, swollen, blistered, dry, thickened or cracked. Changes can appear hours or days after contact. The hands and face are commonly affected, but the rash may occur anywhere exposed to the trigger.
Common Triggers
Triggers include nickel and cobalt, fragrances, preservatives in cosmetics, hair dye ingredients, rubber chemicals, adhesives, some topical medicines and textile dyes. A substance can become a trigger even after years of previous use without problems.
Diagnosis
Diagnosis is based on the appearance and location of the rash and a history of substances used at home or work. Patch testing may be recommended to identify delayed contact allergies. Patch testing is different from skin prick testing used for some immediate allergies.
Treatment
Avoiding the confirmed trigger is the main treatment. Emollients help protect and moisturise the skin. A healthcare professional may prescribe a topical corticosteroid for an active flare. The strength and length of treatment depend on the body area and severity.
Seek medical advice if the rash is severe, persistent, infected, affecting the eyes or interfering with work or sleep. Get emergency help for breathing difficulty or swelling of the tongue or throat, as these are not ordinary contact dermatitis symptoms.
Sources
Reviewed 28 August 2026.