Skin allergiesOver dinner with a friend this week, our chitchat segued into a conversation about her skin. She complained to me about her sensitive skin and frequent rashes. Then she said something that struck me…the doctor said she wasn’t allergic to anything. I told her that she was clearly allergic to something, but she argued with me, saying that all her tests were negative. I explained to her that allergy patch testing can be helpful, but that it often turns up negative results even though you might still have allergies.

A woman gets skin allergy patch test for contact dermatitis at the dermatologist

Patch Testing

The process can be tedious, taking several days of doctor’s visits.  You’ll have your first appointment on a Monday or Tuesday. At this appointment, they will place small amounts of common allergens on your skin and cover them with sticky patches. They will do this until the majority of the skin on your back is covered, generally testing for 30-100 of the most common allergens, everything from common fragrance ingredients to preservatives to medications. You will return to the office to have the patches read 24-72 hours later, and possibly even another 24 hours after that, depending on the results of the first reading. You cannot get the patches wet during this time, making it difficult (though not impossible) to shower or work out. You may also develop rashes on your back that can cause discomfort and itching.

If you and your doctor have decided to proceed with patch testing, make sure you understand what your results mean. So remember that the test only checks a limited number of the most common allergens. The good news is that you’ve narrowed the field of possibilities that are likely to cause problems. The bad news is that you still come in contact with thousands of other ingredients to which you could be allergic. Also remember that it checks for common allergens, not common ingredients. This means that if you’re allergic to an ingredient that is in a lot of products, but you’re the only one allergic to it, this test may not give you all the information you need. You may find out that you are allergic to some ingredients, but you may still have more allergies to other ingredients not covered in the test. Finally, I have had many clients who were allergic to something on just one part of their face, like lips or even just around the eyes. Facial skin is typically thinner and more reactive, so testing for something on your back may not necessarily uncover all allergies. If you figure out that something irritates the skin on your face, I would avoid all contact with it no matter what.

I feel like patch testing is a great way to gather information, but it’s important to understand what you’re testing for and why it may not always work. The more you know about your allergies and what your skin can tolerate, the better you will be able to find skin care that works for you. But remember that it is often only one of the many methods that you may need to use in order to isolate your allergies. Be sure to consult your dermatologist if you are having chronic problems with contact dermatitis. A patch test may be the perfect place to start your search, and your doctor can guide you.

More questions about allergies and patch testing? Email me questions or leave a comment below!