If your cat has been diagnosed with hyperthyroidism, it is likely that one of the options your vet has discussed with you is giving Kitty medication to manage her illness. Methimazole is often prescribed to control thyroid levels, but you should be aware of its pros and cons.
Medication: Treatment - Not a Cure - for Hyperthyroidism
The first thing to understand about using medicine for Kitty's condition is that it won't cure her illness. Hyperthyroidism occurs because the thyroid produces too much thyroxine. Medication won't stop the production of thyroxine, but it will regulate its production so that it's at a normal level. Because it's not a cure, it will mean Kitty will be on this medicine the rest of her life.
Pills? My Cat Hates Pills!
Methimazole comes in pill form, and you may have to pill your cat as little as once a day or as often as three times a day -- it will depend on her T4 level. A T4 level is the measure of thyroxine, the hormone secreted by the thyroid. Like their owners, many cats don't cope especially well with taking pills. Fortunately, there's an option for a transdermal version of this medication. If you go that route, the medicine will come in a gel form to be administered on the hairless portion of the inside of Kitty's ear.
The Good and the Bad of Medication
There are pros and cons to using medication for cats with hyperthyroidism. On the upside, for a cat that is easy to medicate, it is a relatively easy and cost-effective means of managing her illness. Some cats, however, can experience serious side effects from methimazole, including decreased appetite and vomiting. As well, if you go this route, Kitty will require ongoing testing of her T4 levels to ensure the medication is working properly.
If Medication Won't Work for Kitty
If your cat is one of the few that do not respond well to methimazole, there are other options to discuss with your vet. Surgery and radioactive iodine therapy are also options. While they appear to be more expensive than medication, in the long run they may be more cost-effective, as they actually cure the condition instead of merely treating it (meaning no more T4 tests and medication).
Hyperthyroidism is a relatively common illness among older cats. Together with your vet, you should be able to work out a course of treatment that will work for you and Kitty.