Tests and diagnosis

By Mayo Clinic Staff

The key to successful treatment of contact dermatitis is identifying what's causing your symptoms. Doctors rely on two chief strategies to determine the cause:

  • A thorough medical history and physical exam. Your doctor may be able to diagnose contact dermatitis and identify its cause by talking to you about your signs and symptoms, questioning you to uncover clues about the culprit, and examining your skin to note the pattern and intensity of your reaction.
  • A patch test (contact delayed hypersensitivity allergy test). If the cause of your rash isn't apparent from your history and symptoms, or if your rash recurs often, your doctor may recommend patch testing. During a patch test, small quantities of potential allergens are applied to adhesive patches, which are then placed on your skin. The patches remain on your skin for two days before your doctor evaluates your response. If you're allergic to a particular substance, you develop a raised bump or a reaction limited to the skin just beneath the patch.
Jul. 30, 2011