What is Allergic Contact Dermatitis?
Allergic Contact Dermatitis is an extremely common condition involving cells in the immune system reacting to physical contact with an allergen. As opposed to IgE mediated reactions related to environmental, food or medications allergies, this reaction involves T lymphocytes which are also part of our immune systems. Reactions include a rash which can have fluid filled blisters and/or be extremely itch.
The most common contact allergen is poison ivy but other examples can include metals, topical drugs, preservatives, and fragrances. Patch Testing is a common method used by dermatologists and allergists to identify specific substances that may be causing an allergic reaction on the skin.
What occurs during patch testing?
During patch testing, small amounts of various allergens are placed on the skin on adhesive patches and left in place for a specific period of time, usually 48 to 72 hours.
After the patches are removed, the skin is examined for any signs of a reaction, such as redness, swelling, or blistering. The results of patch testing can help healthcare providers determine which substances may be causing a patient's allergic contact dermatitis, so that they can recommend appropriate avoidance measures or treatment. Patch testing is typically done on the back or upper arms, where the skin is less sensitive.
It's important to note that patch testing should only be done under the supervision of a healthcare provider, as some allergens can cause severe reactions in certain individuals. It is also important to follow any specific instructions given by the healthcare provider regarding care of the skin during and after patch testing.