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Delayed allergy is a contact allergic reaction triggered by a chemical agent, resulting in dermatitis (rash) but not hives or shortness of breath.

Delayed allergic contact dermatitis cannot be directly distinguished from other types of common rash by its symptoms or appearance. Contact dermatitis erupts or worsens within 1 to 7 days following skin contact with the substance responsible (the allergen).


Contact dermatitis is often reddish and itchy, and there may be skin swelling, scaling or sores and tissue fluid secretion. The rash erupts at the contact site with the allergen but can also spread around it. The trigger can be hard to identify, as the rash will come and go depending on exposure. The most common triggers are perfumes and preservatives in cosmetics and toiletries, as well as nickel. Other triggers include rubber chemicals, ingredients in plastic and glue products, and compounds of chromium and cobalt. Fitting nail or eyelash extensions may cause sensitization to acrylates, which are strong contact allergens.

Delayed contact allergy is diagnosed by means of epicutaneous testing (patch tests) requested by the dermatologist. If necessary, an application test will be carried out on the skin.

Allergic contact dermatitis can occur:

  • on the eyelids, the face or the neck (hair products, cosmetics)
  • in the armpit area (deodorants)
  • on the hands and wrists (leather, chemicals, metal, work tools)
  • between the buttocks and in the groin (haemorrhoid creams, suppositories and topical antifungals)
  • on the upper or lower legs (socks, rubber boots)
  • on the feet (metal, rubber, leather, dyes, glues, chromium, antifungals)


  • The most effective treatment is to avoid skin contact with the substance causing the allergy.
  • Allergic contact dermatitis can be treated over a few weeks using a corticosteroid cream available at pharmacies without a prescription.
  • If you suspect that a particular job or substance triggers or worsens the rash, seek treatment. Allergic contact dermatitis may become chronic within three months, which is why seeking treatment and diagnosing the problem should not be delayed.
  • If you’ve been diagnosed with contact allergy to a preservative or perfume in a cosmetic product, you’ll find details about skin care products and cosmetics provided by the Helsinki Allergy and Asthma Association on

Dermatologist 22 February 2023