Sea salt is touted as a natural way to kill fleas and can sometimes kill adult fleas, but it is an unreliable way to eliminate fleas from the home or yard. Sea salt or any other kind of salt cannot kill flea larvae.
Adult fleas do not stay permanently on hosts and often hop off to carpets or furniture. Vacuum or steam clean carpets and furniture. Sprinkle sea salt liberally in carpets. Sprinkle sea salt in lawns, although birds and insects may eat the salt.
Sea salt is thought to kill fleas by dehydrating them. But vacuuming and steam cleaning without using salt can also kill adult fleas and flea larvae. So using the salt is probably unnecessary if a home is regularly vacuumed.
Adult fleas die in salt water, according to the Environmental Health Association of Nova Scotia. If you can't bring pets to the ocean, make a bath with sea salt and water and dip the pets in it.