While fleas are able to get into your hair if you hold a flea-infested pet close to your head or lie down in an infested area, most won’t stay there long. Fleas prefer the thick hair of animal fur, so even if they do get in your human hair, most will soon leave to find a new host. However, the Pulex irritans, a.k.a. human flea or house flea, is a species that lives on human blood and may stay in your hair.