Check the ingredient list. Does it contain, for example, either benzoyl peroxide or hydrogen peroxide? Benzoyl peroxide is found in a lot of skin care products and can bleach pretty dramatically over time.
Back in my bad acne days I eventually gave up on all benzoyl peroxide products. My clothes, towels, pillow cases, sheets, etc. were getting bleached from the products I was using. No matter how carefully I put the stuff on my face my eyebrows and hairline would get bleached too -- brown hair will get an orangish cast to it.
Or get an old washcloth or something you're willing to sacrifice and put some Headslick on it for a few hours and see what happens.
