Hydrocortisone cream is one of the first and best things that you can apply to flea bites.
Hydrocortisone is a steroid helps reduce inflammation and swelling associated with flea bites. It can also help to mitigate the itching and skin irritation as well.
You should use a 1% hydrocortisone cream which can be obtained over the counter at your local drugstore for meager price.
It should be topically applied directly to the flea bites and the surrounding skin, which can then be covered with gauze or a Band-Aid in order to further protect the skin.