Q. Can I use a flea treatment after using a flea shampoo shes an older cat
A. It depends on the type of flea product you have used. Read the instructions on the shampoo and see what it says about when you can reapply, this would be a safe time frame to apply a spot on. If your cat still has fleas you should see you vet to get a good quality flea product as the over the counter ones are not as effective. depending upon the active ingredient in the shampoo there may be an alternative that the vet can prescribe in a shorter time period.