How long until Crest whitening strips work?

[garey]

Anyone that is used them? When did you see a difference?

I've done 4 days and see no difference but have a lot of sensitivity.

i noticed a difference after one use and no sensitivity. That's a shame you haven't noticed a difference.

Are you using the proper hard-core ones imported from the US? UK crest strips are rubbish as they aren't allowed to include the bleaching ingredient that the US ones have. Probably better for your teeth though..