Patch Testing / Contact Dermatitis

Many people who experience itchy skin or unexplained rashes could have an underlying allergy. Patch testing is a way to establish if this is the case and, if so, what the patient is allergic to.

Unlike atopic dermatitis – or eczema – which is an autoimmune condition, contact dermatitis refers to rashes or lesions that are a result of something a patient has come into contact with triggering an allergic reaction. Patch tests allow doctors to find out what the patient’s specific triggers are so that they can be avoided.

Contact Dermatitis Patch Test: What to Expect

Patch testing is a painless process that doesn’t involve any needles. Instead, over 20 small patches infused with different test substances are applied to the patient’s back. These are left on for around 48 hours and an initial reading is done. The results aren’t available immediately as it can take between two days and a week for the skin to react. A second and sometimes a third reading is done after a few more days to get the final results.

While the treatment itself isn’t painful, a positive reaction from a patch test will cause active contact dermatitis at the application site. In some cases, this can lead to a more widespread rash.

Common Skin Aggressors

Unlike prick testing, which identifies the culprits behind conditions such as hayfever or asthma, patch testing reveals the cause behind a patient’s contact dermatitis. This refers to allergies that occur on the skin. Some common aggressors include:

  • Dyes
  • Active ingredients
  • Preservatives
  • Fragrances
  • Cosmetics

Patients receiving patch testing are advised to bring skincare items with them to their consultation. This can help the dermatologist identify the product that’s behind their rash or concern.

Set Up Your Appointment With a Dermatologist Today

Do you want to find the cause of your allergic contact dermatitis? Use the buttons below to find a clinician or location near you that offers patch testing.

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Call us at: (978) 759-4032