I was wondering if you could mix skin lighteners.?

From the Meladerm website it says "We do not recommend you directly mix the product with any other substance. You may use additional moisturizers, toners and cleansing products in routine with our products. Please test for skin irritation when using multiple products on the face and body."

Does anyone have any more information on this?

No, I wouldn't mix products together , for what? If you don't think the product isn't strong enuf , try something else, because by mixing products you might get sum type of allergic reation, and it will take away from the lightening affect.