Why do I still have tachycardia?

I took methimazole for 2 months and my levels are now more on the hypo side so my endocrinologist told me to stop methimazole. Why is my resting heart rate still between 100-110 even though my F3 and F4 levels are normal??? I stopped taking beta blockers because propranolol gave me bad side effects (I ended up in the ER) and bisoprolol makes me feel sick. I dont understand why my heart rate won't go down? Has anyone else gone through this? I'm losing hope.

I did have it when hyper and then again when my levels were on the lower end of the scale. I  especially got it with Acetyl-L-Carnitine.  I only use Propranolol sparingly, taking 1/2 of a 5 mg pill when I felt it was necessary but did not take it steadily.

Hi Gray,

I have started Carbimazole 2 weeks ago and I can see already some benefits: I sleep better, I don't twitch as much at night, I have lost the tremors and got my periods back. However my resting heart rate is still very high, in the 80ies, while it used to be 50 (I am a long distance runner.. well I was before this thing). I know it's early and I will wait and hope while on Carbimazole.

Were you able to do any training these two months? What was your resting heart rate before the onset of hyperthyroidism?

Hi grayesthistle, it would be good to have this investigated by a physician. There are other factors besides abnormal thyroid values that can cause an elevated resting heart rate. An electrolyte imbalance (with low levels of Potassium) might cause an elevated resting heart rate. This could happen for example if the kidneys are not working properly. 

 Hi grayesthistle

I had tachycardia every night at bedtime for about 20 mins when I was young.  Unrelated to your question, I know, but I had all kinds of tests and no one came up with an answer. I wonder now if it wasn't from thyroid. Anyway -  I don't have it anymore but I take water pills for BP and sometimes wake in the morning with pounding heart. I find this happens when I'm dehydrated. I hope you feel better soon.