You can use any puppy/ dog shampoo or a natural NEEM shampoo made for pets. I like Ark Naturals 'Neem' Protect Shampoo:
https://arknaturals.com/dog/grooming...octect-shampoo
1. wet the dog
2. put a ring of shampoo around the neck & lather it up...this will prevent the fleas from scurrying up to the face (They actually go inside the eyes & ears, I've seen it!
Not my dogs but a dog that I groomed.)
3. put shampoo everywhere else & lather up...this will kill the fleas or they will jump off the dog & go down the drain w/ the water
If you have a flea comb, comb very thoroughly for any left over fleas. Have a cup of water handy to drown them in. Oh & check the inner thigh area, as they hide there...less water reaches there.
I'm sure you've read all the other preventative measures, like vacuuming, wash bedding, etc. Repeat.