Hamsters do not get fleas very often, but sometimes cat or dog fleas will temporarily infest them. Because small rodents can be very sensitive to treatments that are perfectly safe for larger animals, you must take care when treating the infestation. It is best to treat the fleas without using any medications on your hamster. If the fleas are persistent, consult your vet before using an over-the-counter treatment.
Take your hamster out of its cage and place it in a pet carrier.
Put all old bedding and cardboard toys or boxes in the refuse bag and tie the top tightly. Place it in an outside rubbish bin.
Vacuum the cage and surroundings thoroughly. Pay particular attention to carpets and soft furnishings in the vicinity, which form a nursery for flea eggs and larvae.
Wipe the cage and plastic accessories down with hot water with a little dishwashing liquid mixed together in the bucket. Dry with paper towels.
Replace accessories and add fresh bedding before returning your hamster to the cage.
Treat your other pets, in particular cats and dogs, with treatments appropriate to the species. It is likely the fleas are coming from them.
Treat the hamster and bedding with a flea powder specifically for small rodents, if the hamster is still infected after a week or so. Kitten flea-powder may also be safe, but check with your vet first. Follow the instructions on the packaging exactly. Usually, you dust a very small amount of powder into the animal's fur and brush out any excess with a toothbrush or other small brush, as well as dusting the bedding.
Be sure your hamster actually has fleas before using a flea treatment. If you do not see any fleas, only your hamster scratching, it is more likely the hamster has problems with mites. If in doubt, it is always safest to consult your vet. If money is tight, contact a local hamster club or other small rodent club for help and advice.