Patch testing
This is useful for patients with delayed reactions. For example, it can determine what chemicals you are allergic to. In general it is only used if you have skin reactions to certain chemicals, such as to jewellery, or hair dyes.
Because it is looking for a delayed reaction, the patch is usually applied on one day and then you need to return 2 days later to have it removed and read for the results.
back to Disease Info - Allergy
