Contact dermatitis is a term used when certain substances cause a rash, when they come in contact with your skin. Contact dermatitis can be divided into two types: allergic and irritant.
Allergic contact dermatitis
Allergic contact dermatitis is caused by “allergy” cells in the skin reacting against the offending substance (“allergen”). Symptoms include the red, itchy and blistering rash. Typically the rash begins about 24 to 48 hours after contact, and will occur wherever the allergen contacts the skin. The reaction can last anywhere from 7-28 days, with or without treatment. Frequent exposures decreases the time to development of rash and hence, symptoms may begin a few hours after contact.
Common Offending substance ("allergen")
- Reactions to plants like poison ivy, poison oak, sumac, mango
- Metals like nickel, which is found in most jewelry
- Certain perfumes and dyes
- Rubber (latex) products
- Topical medications like neomycin
Even products that have been used without problems for decades, can become allergens
What can you do?
Consultation with a board certified allergist for a detailed history, physical exam and patch test to determine the offending substance is the first step.
Skin Patch Test
The patch test involves applying various chemicals on the back for 48 hours. The patch is removed and interpreted after 72 hours. A positive test will show a small patch of redness, swelling or blistering at the site of a particular chemical.
Treatment of Allergic Contact Dermatitis
Acute treatment for allergic contact dermatitis includes use of medications (antihistamines, topical or oral corticosteroids) for acute treatment. The treatment modality depends on the severity of the reaction. Long term treatment includes strict avoidance of the identified “allergen” once identified.
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