Reactions to TRUE Test™ (Allergen Patch Test) should be read 72 to 96 hours after application. This time span is necessary for allergic reactions to develop fully, and for irritant reactions to subside. At approximately 48 hours the patch should be removed; readings at this point are preliminary and should be confirmed at 72 to 96 hours.

Neomycin sulfate and p-Phenylenediamine (PPD) sometimes cause late reactions that appear 4 to 5 days after application. Patients should be instructed to report these. If appropriate, an additional office visit will verify a late reaction.8

It is important to note that PPD may turn the allergen test area black on some patients. This is because the allergen is a dye; it does not represent an allergic reaction. This discoloration may remain for up to 4 weeks.8

An identification template is provided with each test for quick identification of any allergen that caused a reaction. To ensure correct positioning, marks on the skin should correlate with the notches on the template.

The identification template supplied with TRUE Test™ ensures accurate identification of the allergen patch responsible for a given reaction.