| Patch test | |
|---|---|
 Patch test | |
| Specialty | Immunology, dermatology |
| MeSH | D010328 |
A patch test is a diagnostic method used to determine which specific substances cause allergic inflammation of a patient's skin.
Patch testing helps identify which substances may be causing a delayed-type allergic reaction in a patient and may identify allergens not identified by blood testing or skin prick testing. It is intended to produce a local allergic reaction on a small area of the patient's back, where the diluted chemicals were planted.
The chemicals included in the patch test kit are the offenders in approximately 85–90 percent of contact allergic eczema and include chemicals present in metals (e.g., nickel), rubber, leather, formaldehyde, lanolin, fragrance, toiletries, hair dyes, medicine, pharmaceutical items, food, drink, preservative, and other additives.