Doctors Foster and Smith recommend using a product containing pyrethrins, which is the same ingredient found in some products used to treat fleas in cats, to treat fleas in guinea pigs. Pyrethrins are natural chemicals extracted from the flowers of chrysanthemums.
Pyrethrins kill fleas by interrupting communication between the cells of the nervous system. Many products formulated to treat fleas in cats and dogs have not been tested on guinea pigs, so it is important to consult a veterinarian before choosing a guinea pig flea treatment. Using a flea comb to remove live fleas and flea dirt from the guinea pig's fur is another way to keep fleas at bay.