Dr. Dele-michael

Allergic Contact Dermatitis and Skin Allergy Test

Allergic Contact Dermatitis and Skin Allergy Test

What is allergic contact dermatitis?

Allergic contact dermatitis is an itchy, usually chronic rash caused by exposure to substances in the environment. Contact dermatitis may have characteristic distribution patterns indicating that the observed rash is caused by external rather than internal stimuli.

What causes allergic reaction of the skin?

There are many allergens that can trigger an allergic reaction of the skin. The top ten allergens, as identified by the North American Contact Dermatitis Group are:

  • Nickel sulfate – metal frequently encountered in jewelry and clasps or buttons on clothing and belt buckles
  • Neomycin sulfate – topical antibiotic found in Neosporin
  • Balsam of Peru – naturally occurring fragrance used in perfumes and skin lotions
  • Fragrance mix – a group of the eight most common fragrance allergens found in foods, cosmetic products, insecticides, antiseptics, soaps, perfumes and dental products. Fragrance mix is added as fragrance to many products. Unscented products may contain a masking fragrance so look for products labeled “fragrance-free”
  • Thimerosal – added as preservative to many skin and eye care products
  • Gold (gold sodium thiosulfate) – precious metal often found in jewelry
  • Formaldehyde – a preservative with multiple uses, e.g., in paper products, paints, medications, household cleaners, cosmetic products and fabric finishes
  • Cobalt chloride – metal found in medical products; hair dye; antiperspirant; objects plated in metal such as snaps, buttons or tools; and in cobalt blue pigment
  • Bacitracin – a topical antibiotic
  • Quaternium 15 – preservative found in cosmetic products such as self-tanners, shampoo, nail polish and sunscreen or in industrial products such as polishes, paints and waxes

What is patch testing?

Patch test is the gold standard method for diagnosing allergic contact dermatitis, performed by a skin allergy expert in New York City, for example, at the Radiant Skin practice. Patch testing identifies contact allergens that may be causing allergic skin reaction in patients with contact dermatitis (eczema). Patch testing involves application of diagnostic stickers with common allergens usually on the patients’ back with the intention of causing a localized reaction to the offending allergen. The number of allergens tested can vary from 50-175 depending on the suspected cause of the allergic reaction.

Prior to patch testing, patients are advised to avoid taking oral steroids. It is okay to take an oral antihistamine such as Allegra, Zyrtec or Claritin.

I had a positive patch test, what is the next step?

After Dr. Dele-Michael completes the skin allergy test in NYC at our practice and the offending allergen is identified, you will be given a list of what you are allergic to and where they are commonly found as well as a list of skin care products that do not contain the allergen and are therefore safe for you to use.

I have been using this skin product all my life, why am I allergic to it now after 20 years?

This is the most common question that individuals with allergic contact dermatitis ask. Susceptible individuals can develop an allergic reaction if they become exposed to a high dose of the allergen at once or if they are exposed to a high cumulative dose of the allergen over a period of time.

Determining the offending allergen causing your skin rash can be challenging, but patch testing can be very helpful. The cornerstone of effective management of symptoms is allergen avoidance. Prescription topical steroids can alleviate the symptoms.