My vet also recommends vecta. I did buy it and use it this time; however, I only used a half of the tube on each of my girls. I didn't see any type of reaction from them or notice a bad smell at all. I have not seen any fleas at all. Both girls have had ticks. Rosie one and Mikki three.
All are dead when we pulled them off. So I do think the 1/2 a tube is still working. My vet don't even sell Frontline any more. And is highly pushing Vectra.