Cats worse scratching

My cats are scratching worse 8 days after flea treatment. Would it help to bathe them?

It sounds to me as though your cats need to see a vet so that the cause of the scratching can be found.  You don't tell me the nature of the flea treatment so it is hard to understand whether it was appropriate for your cats' itching or not (for instance, dose or efficacy or side effects etc - not every flea treatment kills every flea!) If not, it may simply need to be repeated with a more appropriate drug, but if it was then other causes of itching may need to be considered and ruled out.    Scratching is often a chronic symptom i.e. one that happens a little over a long time, and therefore generally is 'controlled' rather than got rid of, much like diabetes or kidney disease. Bathing is a difficult one, but most cats hate it and it's hard to see how it helps.  A vet appointment might be preferable.

I should add that Inn cats with allergies, literally bathing or wiping allergens from the coat can be helpful, but it sounds very much as though more treatment and understanding may be needed in order to help your cat maximally at this stage.