What is the difference between patch testing and a full allergy test?

• A. Patch testing is medical and performed by clinicians; full allergy testing is done at home.
• B. Patch testing checks skin reaction to products; full allergy testing is medical and performed by clinicians.
• C. Patch testing tests for all allergies; full allergy tests only fragrance.
• D. Patch testing and full allergy testing are interchangeable.

Answer: (B)

Patch testing focuses on identifying a skin reaction to specific substances that may cause contact dermatitis. Substances are applied to the skin under patches and observed for a delayed reaction (usually checked after 48 to 72 hours). This is a procedure done by clinicians in a clinical setting to pinpoint which product or allergen is triggering the skin issue.

Full allergy testing covers broader allergic reactions, often involving tests like skin prick testing or blood tests to detect immediate-type (IgE-mediated) sensitivities to things such as foods, pollen, or insects. These are medical tests performed by trained clinicians because they assess systemic risks and require proper interpretation and guidance for management.

So, patch testing is a skin-focused, clinician-led test for contact dermatitis, while full allergy testing is a medical assessment for a wider range of allergies.