I don't know if anyone has tried this before but we have had an awful time with fleas this summer - vet recommended a pill called Comfortis.
Gave it to cats in the evening, by morning tiny dead fleas everywhere!!
Bit grim, but so far I am so impressed. You are supposed to use it in conjunction with spot on and after spraying the house if anyone wants to try it
Will update in a few days when it's more obvious whether the fleas have definitely gone or not - but thought I would post about it now because I've been at my wit's end and want to share the love 