To test whether you may be allergic to a certain cosmetic, topical medicine, or skin-care product, you can perform a use test.
Apply a small amount of the product on a patch of your skin about the size of a quarter, twice a day. Use the underside of your forearm about halfway between the elbow and the wrist. Repeat each application on the exact site. It will not interfere with the test if you bathe and wash your hands as usual.
Continue the test twice a day for up to 10 to 14 days. Stop the use test if a rash develops. Show the test site to your physician or photograph it.
If a rash develops at this site, it may mean that you are allergic to something in the product and should not use it on your skin. If a rash does not develop on the test site, it is probably all right to use the product on your skin.
NOTE: The use test should NOT be done with soaps, cleansing agents, detergents, or shampoos because these substances can cause irritation which cannot be distinguished from an allergic reaction.
