transdermal methimazole for cats

Recently, my cat was tested for hyperthyroid. Because he was borderline, the vet wanted to give him a month of methimazole to see if there was a change in his behavior and eating habits, etc. I've been giving it to him, twice a day, on the right ear in morning, and left ear at night. Last night he started scratching his ear, and then I looked, and both ears were bright pink/red, hot, and scabby on the edges. I stopped the medication, and looked on line for some information. I haven't been able to find much. Does anyone have experience with this sort of thing? 

Thank you.

I've no experience of this sorry. But I just wanted to say I think you have done right thing, to stop using it. I would get in touch with your vet as soon as you can, to see what they say.

Sorry I can't help more but maybe others on this site have some Information for you.

Are you rinsing off in between dosages?  I used to have a hyperthyroid cat, we would wash her ear off about midway between dosages.  Sounds like she is getting some irritation from the gel buildup.

I agree, stop with the medication till you have checked with your vet.

Does the irritation look like it is from the medication, or from him scratching at it?
It may be the carrier that is causing the irritation, not the methimazole.
Ours was made up at a formulating pharmacy monthly, rather than something that is made up and per-packaged.
We had a lotion rather than a gel. It may be possible to get it formulated in a different base.
just like humans, different cats are going to be sensitive to different things.

Our cat never had any irritation. We only cleaned the sites if it looked like there was build up that would impede the dose from being absorbed, which was not often. Either it absorbed really well, or she groomed it off. On the occasion that there was build up, we used a cotton ball and a drop of salad oil. How you clean the sites depends on the carrier- gel, lotion, etc.

If you do try another formulation,donate the unused doses back to your vet. (I would be surprised if anyone would do a cash return).
When our cat passed we had almost a whole month made up. The vet said they had several clients struggling to afford the medication, and they would give them Pippi's unused doses.

Thank you for your replies. I stopped the medication. When the clinic opened, I called in and the vet said to put the medicine on that night and the next morning, and then bring him in the morning for another blood test. However, that night, his ears were leaking, and obviously uncomfortable, so I didn't put the meds on again. When I took him in, they said it was the worst reaction they have seen with that medicine, so they stopped that, and gave me Mometamax to put on his ears to help heal them. They will call me with the blood test results and then we will see about getting him the one time treatment for his thyroid.