On 23 May, 12:08, calvin wrote:

I don't want to make the cat sick even once just to
find out if the interferon makes him sick or not. *

Fair enough no one wants to make a cat sick- so how about now calling
the vet and discussing it with him or her?

Antibiotics will cure an infections but they have no effect wahatsover
in Feluk

I would really just call your vet and explain that you're uneasy about
the interferon because you've read/heard it makes the cat feel unwell.
I'd ask them to justify the prescription/dose and how that will impact
on the cats quality of life etc.
If your vet is halfway decent they'll take the time to go through the
options with you

Lesley

Slave of the Fabulous Furballs