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Allergic Contact Dermatitis

Frequently Asked Questions

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice.        

For patient or carer support contact Allergy & Anaphylaxis Australia or Allergy New Zealand

pdfASCIA PC Allergic contact dermatitis FAQ 2024128.69 KB

Q 1: What is allergic contact dermatitis?

Allergic contact dermatitis appears as an itchy, weeping, rash, on the area of the skin that has come into contact with an allergic trigger (allergen). It usually develops two or more days after contact with the allergen. If contact with the allergen continues, the rash may continue for several days or longer.

Q 2: What are the most common causes of allergic contact dermatitis?

Common causes of allergic contact dermatitis include nickel, chemicals, plants, cosmetics, perfumes and ointments. Nickel allergy is the most common cause and is more likely in females than males.

About 8% of the population have an allergy to nickel, a chemical element that can be found in the metal of costume jewellery, watch straps, bra clips and jeans studs.

A few days after contact with the metal that contains nickel, an itchy rash can develop, which may blister and weep. If contact with the metal continues, the rash may continue for several days or longer.

Q 3: Do plants cause allergic contact dermatitis?

Some plants can trigger allergic contact dermatitis and rashes may appear on exposed areas of the body after being outdoors. Allergic rashes triggered by direct contact with plants and sunlight is known as photo-contact dermatitis.

Plants that may cause contact dermatitis include chrysanthemums, primula, tomato plants, grevillea, English ivy and Rhus trees. Lantana or vegetables such as parsnip or celery may cause photo-contact dermatitis.

Q 4: Do chemicals cause allergic contact dermatitis?

Chemicals in rubber, leather and some dyes can cause allergic contact dermatitis. It is common for people to develop dermatitis to shoes, as they often contain one or more chemicals.

Contact with chemicals and irritants in the workplace may cause contact dermatitis in workers who:

  • Are in contact with dyes, glues, acids such as lemon juice, and alkalis such as wet cement.
  • Work in very hot or very cold temperatures.
  • Frequently wash their hands.
  • Wear personal protective equipment for long periods of time (such as nurses and people working in the food industry).

Q 5: Do skin creams and ointments cause allergic contact dermatitis?

Creams and ointments used on the skin may also cause allergic contact dermatitis. The cause may be the base ingredient such as lanolin, or the active agent (antibiotics such as neomycin). A rash will generally appear around 10 to 14 days after the cream or ointment is applied for the first time. If the same cream or ointment is applied again, a rash can develop about two days after it is applied. Perfumes on their own or added to cosmetics, moisturisers, and sunscreens can also cause a reaction.

Q 6: When is testing for contact dermatitis needed?

If the cause of allergic contact dermatitis is unclear, patch testing can be helpful. These tests are usually performed by a medical specialist (dermatologist or clinical immunology/allergy specialist). This involves applying a small amount of the suspected allergen/s to the skin, usually on a person’s back, covering the areas with hypoallergenic tape, and seeing if a reaction occurs after a few days. If the cause of contact allergic dermatitis is confirmed, avoidance of the allergen/s should prevent symptoms.

© ASCIA 2024

Content updated June 2024

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