5mg a day had no effect, so we upped it to 10mg three weeks ago. Last week it looked as if he was responding, with weight gain and a return to normal feisty temperament. Now lethargic and has just vomited everything he has eaten today. Spoken to vet who says the meds are sending him toxic.
We're going in tomorrow to discuss surgery, but does anyone know how long it will take for the symptoms of the toxicity to pass. He has now not succeeded in retaining anything he has eaten since Saturday.
My cat had a bad reaction to felimazole, he became very lethargic & looked pale - the felimazole had badly affected his blood cells. The vet booked him in for surgery the following week, saying that yes there was a risk with the anaesthetic but his thyroid was only going to get worse if left untreated and there was no option apart from the surgery (we had already ruled out radioiodine). Stopping felimazole did perk him up a bit and the op was successful & uneventful. He survived for 2 more years so it was well worth doing (he was 16 at the time of the op) Good luck to you & your cat
Often with the vomiting we control that with anti-emetics then feed before felimazole so it goes in on a full tummy. I have never had to stop treatment due to vomiting, I gave had to stop due to other side effects.