Diagnosing Contact Dermatitis
When diagnosing contact dermatitis, your healthcare provider will look at your rash and will ask several questions related to your symptoms, occupation, and current medications. If your healthcare provider is still unsure about whether you have contact dermatitis, he or she may also recommend certain skin tests (known as patch testing).
In order to make a contact dermatitis diagnosis, your healthcare provider will begin by asking a number of questions, including questions about:
- Your current symptoms
- When your symptoms began
- Other medical conditions you have
- Your current medications
- Your occupation
- Your skin care products.
He or she will also ask about any allergies that you have, and whether symptoms improve during vacation or on the weekends.
Your healthcare provider will then look at the rash. Based on the answers to the questions, along with the way the rash looks, your healthcare provider may have a general idea of what is causing your symptoms. If he or she thinks this is contact dermatitis, treatment may be recommended (see Treatment for Contact Dermatitis). If your healthcare provider is unsure, he or she may also recommend additional tests to help narrow down the cause.
In order to make a contact dermatitis diagnosis, your healthcare provider may recommend skin tests (known as patch testing). Patch testing works only in those people with suspected allergic contact dermatitis.
Patch testing is usually used in people that still have symptoms following a trial of avoidance and medications.
For patch testing, the healthcare provider uses a series of medicines, metals, preservatives, rubber compounds, and various chemicals that go by the name North American Contact Dermatitis Group Standard Patch Test Series. A small amount of the suspected allergen(s) is applied to the patient's back, covered with a nonabsorbent adhesive patch, and left on for 48 hours. (The patch is removed if itching or burning develops before that time.)
If redness, hardness, or blistering occurs, the test is considered positive, indicating probable allergy to the substance. Since some reactions do not occur until after the patches are removed, the doctor will take another look at the patch sites in 72 hours.
Other patch test series are available if the tests are negative.