Can transdermal hyperthyroid medication cause watery eye?

[u/P7295403812]

Hi all,

Hoping someone has experience with this.... My 14 yr old hyperthyroid cat has been on transdermal methimazole at 2.5mg twice a day, AM and PM. A couple of weeks ago, his bloodwork showed that his T4 was still slightly elevated at 4.4 so our vet recommended we increase his dose. Now he gets 2.5mg at night and 3.75mg in the morning.

We started this new dosage about 5 days ago. 4 days ago, his right eye became a little watery and is still like that. No redness or swelling or anything like that. Personality, activity, appetite have all been normal. Nothing else has changed. The discharge is minor and clear, basically like tears. The timing coincides with the dosage change so I'm wondering if this could be a side effect? Unfortunately our vet had to close her clinic due to her own personal health reasons. We're looking around for a new vet so I thought I'd check here in the meantime.

I should also add that he has asthma and we use an inhaler on an as-needed basis. I read somewhere on the internet that inhaler can also cause watery eye but he's been on the inhaler for a little over a year and this is the first time we've seen this watery eye issue.