Cat lethargic, not eating on Felimazole. Is the dose too high?
Updated On September 23rd, 2025
Pet's info: Cat | Mixed Breed | Male | neutered | 9 years and 8 months old | 6 lbs
My 11 y/o male cat is taking 12.5 mg of Felimazole a day and now is lethargic, no appetite, but drinks water... Too high of dose possibly?? He seemed fine until a few days ago..
2 Answers
Most Helpful Answer
Published on May 11th, 2017
I am sorry to hear about Midnite. I would call and let your vet know of the symptoms. You don't mention if he just started this medication or if he has been on it long term. Some cats can experience lethargy and GI upset when first starting the medication and in some cases we need to start at a lower dose and taper it up, but you need to consult with your vet in order to know if this is the right course of action for your kitty. If he has been on methimazole for a long time and just started with the lethargy/decreased appetite, then an exam and possibly bloodwork are in order for him to ensure there isn't another cause for his symptoms.
1Pet Parents found this answer helpful
Related Answers from Veterinarians
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Published on March 30th, 2019
Hello. Yes, there are appetite stimulants that we often give to cats & I am sure your veterinarian is aware of this. Common ones are mirtazapine & cyproheptadine. Cerenia is often used just because it treats nausea, and a newer product called Entyce is being used extra-label in cats ( it is only approved for dogs right now, but the company is working on a cat application). One of the adverse effects with Felimazole is the possibility of loss of appetite. Sometimes discontinuing the medication for a few days & restarting at a lower dose gradually increasing to full dosage is necessary. Hopefully, Dutchess will be feeling better soon. Thanks for using Petco Pet Education Center, formerly Petcoach.
2Pet Parents found this answer helpful
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