Problem is, he's allergic to all the different drops and they make his hair fall out so I've stopped completely with flea treatments.

oh wow! I did the drops too and they didn't work. With the powder, please make sure that his head is covered because my cat (the mother of the kitten) seemingly allergic to it. She was like uh, trying to cough and sneezes. Thankfully it cleared up in just 20 minutes. If you can't find that same brand, there's Dorris too and works the same. The kitten were fine with this type of powder treatment and it really was satisfying seeing the fleas die a slow and painful death xD

Hope your cat will be free of fleas soon! take care and let me know if it works for your cat