I got a good point made to me via e-mail responding to one of my posts about methylchloroisothiazolinone and methylisothiazolinone.   He or she desribes themselves by the pathos ridden name foreverbotheredbythisallergy and referring to some products that readers have identifed as free of those two chemicals –

Some the products above have the benzylisothiazoline which can give you the same reaction as the methyl and chloromethylisothiazoline. I have been using Tide Free for years and just now have developed the skin rash. As it turns out it is the benzylisothiazoline in the product. Be warned, the benzylisothiazoline allergy can occur after use over a period of time with a product that has this chemical in it. good luck.

And they are absolutely right.  The medical term for this is cross sensitivity.  If people with allergies didn’t already have enough trouble, it turns out that if you are sensitive to one chemical it might predispose you to get the same reaction to a related one. Continue reading →