Why test for hypersensitivity?
PPD (paraphenylenediamine) is the active ingredient found in permanent hair dye, which is proven to elicit allergic reactions in hypersensitive individuals.
As reported in the press recently, allergy to PPD can cause uncomfortable reactions, which may result in symptoms such as soft tissue swelling, blisters and infection. In rare and extremely severe cases the reactions can be life threatening.
These allergic responses can develop at any time.
Whether a professional or domestic user of hair dye, the simplest way to avoid complications is to test.