Health & WellbeingMy dogs were given a free sample of trifexis on Wednesday and it isn't working at all. I'm still finding them alive on my pets. However, at the vet I decided to buy comfortis pills that I know works because I have used them before. Can I give my let'
Hmm - it's odd that the Trifexis doesn't seem to be working as well, because it actually has the same active ingredient as Comfortis. The only difference is that it has an added ingredient for heartworm prevention, otherwise it's exactly the same drug. In my experience, both are extremely effective for fleas. I wonder if perhaps Tessa is continuing to pick up fleas from somewhere in the environment? It does take a few hours for a flea to die after biting her, so if she is continually being re-infested from the house or yard, it's very possible that you might see live fleas on her even if the medication is working properly. If you think this might be the case, I would recommend treating your house and yard with a premises spray such as Knock-Out. If you still want to get her something else for fleas, I would not recommend giving a Comfortis dose on top of the Trifexis, because this would just be giving a double dose of the same drug - I would be concerned about possible side ef
Updated on August 12th, 2025
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