Hair dye allergy leads to coma

From Huffington Post: A woman goes into anaphylactic shock, possibly having an allergy to para-phenylenediamine or PPD. 

On the Environmental Working Group's Cosmetic Database, there are several versions of phenylenediamine that range from virtually nontoxic at 0 to very toxic hitting 10.  

Several chemicals found in hair dyes are toxic and can lead to adverse reactions in some cases.