Cat seems lethargic. Could Feliway be the cause?

We got a new kitten a few weeks ago. For the first few days, Max seemed fine with him. Hissing, but nothing more and he was acting normal. I then got 2 Feliway diffusers for the house. Since getting them, Max seems to have gone down hill. He just lays on the bed and sleeps all day (much more than usual.) Even my husband noticed.

Could the diffusers be the cause? Maybe they're making him too mellow?

Is it just the introduction of the kitten? (even though he seemed fine the first few days and we keep the kitten in a different room unless we are supervising)

Any ideas? Help!

I would take him to the vets to get checked out. I use Feliway and it has never made any of our cats lethargic. I hope he is ok. Keep us updated.

I use Feliway all the time too and it should just take the edge off. I've never noticed any major personality changes.

Lethargy is not good. I took a cat to the vet a couple years ago for lethargy and it turned out to be a very serious medical problem. Take him to the vet ASAP!

The Feliway should just help your kitty "chill out" a bit, not lethargic. Lethargy, especially if your cat is being anti-social, is a red flag that warrants a vet visit.

I agree that you should take him to the vet. Feliway should relax him but not make him lethargic. You need to get him checked out to be sure the kitten didn't bring in some kind of virus or something.