How long till flea bites go away?

Up to you. If you are allergic to the bites, then they will itch for weeks. If you scratch them, they will itch until you quit scratching them. They can cause hard bumps called nodules if you continue to rub or scratch. Also, are the fleas still around? Other bites can look like flea bites and last a long time, such as scabies and other mites. Hydrocortisone cream and oral Benadryl (diphenhydramine) will help the itch.