After washing the cat, yes. WASHING THE CAT. I put Sergeant's Silver on our cat Deja. About two days later, he started loosing fur where I applied the product. I immediately called the emergency number on the back of the box. They told me to wash the cat. YES AGAIN I HAD TO WASH THE CAT. They told me to use a mild soap such as dish soap, rinse well, then lather up again and rinse well.
Heres a picture of the fur loss on our poor cat. (WHO STILL HAS FLEAS.) *sigh*