and how long do they take to work?
The whitening strips should be used twice a day. The first application should be taken before going to bed and the second one in the morning after showering or bathing. If you use them under your eyes, it is important that you remove all make up before using these products as this will help for more effective results. It is recommended that you leave them on for 20 minutes at least until they go away completely; however, if this does not happen it means that the product was not properly applied and needs to be reapplied again afterwards. Try leaving them on longer next time but avoid sleep while wearing them if possible.