PATCH TESTING: FREQUENTLY ASKED QUESTIONS
Why do I need patch testing?
- Patch testing helps to determine if you have allergies to things that touch your skin such as ingredients in skin care products.
- These ingredients may be found in your skin care products or in materials from home, hobbies, or work.
- Anyone can develop a contact allergy, from young children to adults.
- More exposure to an allergen increases your chance of developing an allergy.
What is patch testing?
- Patches are applied with tape (usually on the back) and these will need to stay in place for 48 hours (two (2) days).
- Patches should be removed and discarded after 48 hours.
Can I take a shower or exercise during patch testing?
- Exercise and shower before you arrive to clinic.
- Usually, we use waterproof tape so that you can take a quick shower even while the patches are taped in place.
- Avoid excessive sweating or exercise for 48 hours while the patches are in place.
- If you are lifting or stretching and you feel the tape pulling, then stop what you are doing.
What do I do if I have itching during patch testing?
- You may have some mild discomfort and itching on your back from the tape or possibly from a positive reaction to a test ingredient.
- Oral anti-histamines and cold-packs may be used to decrease itching during patch testing.
Do I need to stop my medications prior to patch testing?
- Notify the physician or nurse of any medications that lower your immune system, such as steroids, immunosuppressants, or biologics. You may need to stop the medication or lower the dose prior to testing.
- Do not apply topical steroids to the back for two weeks prior to testing.
Can I use lotion or tan prior to patch testing?
- Avoid any type of tanning on your back for two weeks prior to testing.
- Your back must be clear of rash, lotions, creams, and hair to complete the patch testing.
- If needed, shave your back the day before your patch testing.
What should I bring with me to the appointment?
- Bring skin care products that you have used in the area of rash over the past three months. It is helpful to bring them in their original containers or bring a copy of the ingredients contained in the product.
- Wear or bring a dark T-Shirt so that the pen marks outlining the patches do not stain your clothes.
- For younger children, it is helpful to wear a shirt that is 1-2 sizes too small to help keep the patches snuggly in place.
How does patch testing work and what allergies does it test for?
- Patch testing is a process that detects allergic contact dermatitis, and involves applied patches with testing samples to the back.
- Using tape, these patches with test substances are left on the back for a small amount of time to see if a dermal reaction occurs.
- This is a proven process that shows accurate results for many individuals, and the test substances applied are determined by your allergist.
- The patch test does not test for food allergies, but can test for other allergies that cause dermal reactions, such as nickel, fragrances, and preservatives.
How long does a patch test take and what is involved?
- The length of time for the patch test may vary depending on what allergens you are getting patch tested for Because dermal allergic reactions can take some time to show up on the skin, patch testing can involve multiple visits to the clinic for a week, in order to apply the patches, and then test for the reactions.
- Day 0……..Patch test application
- Day 2……..Patch Test Removal (Initial Reading)
- Day ¾……Main Reading
- Normally it takes 3-4 days but one should again visit on day 7