This Adams Plus Flea %26 Tick foaming shampoo for cats does work, but you need to make sure you follow the directions and rinse completely! To eradicate the fleas you'll also need to treat the environment, as the fleas are in the rest of your house or yard.
When our indoor only cats got fleas (so one of us human servants probably brought in a pregnant hitchhiker flea!) a couple of months ago, we did the usual stuff/steps for flea treatment.
Daily vacuuming of carpets, sofas, floors, baseboards. Anywhere the fleas might harbour. Washed cats and our bedding. Also did the household flea spray (locked up the cats in the other room until spray dried completely) on the carpets and other areas the cats hung out and would most likely drop flea debris, eggs, etc.
But we also decided to bathe the cats because the flea "dirt" on them was so disgusting. This Adams flea shampoo is for cats. There is a lot of controversy on these flea shampoos for cats because the ingredients could be toxic and people have reported that their cats died or got very sick.
So we took a very cautious approach to help limit too much exposure and used the Adams cat flea shampoo (make sure it's labeled for cats, as dog products are toxic to cats!) only as a thick foam ring around their necks, as fleas tend to crawl up the skin and fur towards the head to escape the bath water. We used a regular non flea cat shampoo for the rest of their body.
We also made sure to rinse them off several times and super well to remove any residue that they might lick on their body.
We also used the flea medication drops on the back of their heads (where they can't lick directly) and also used the tape worm de-worming pills, as cats can get tapeworms from ingesting fleas. Two of the cats groom each other, so we used the Seresto collars on those two instead of flea drops.
After two months of vacuuming, flea combing daily to check for fleas, dirt, eggs, we haven't seen any fleas (or tapeworms) so we think we caught and stopped the flea invasion before it took a major hold. But we will continue to put on the monthly flea drops and use Seresto collars on the other cats who groom each other, to be safe.
So make sure you use flea products labeled for use on cats and follow directions carefully and it should work.