It not only keeps your blood pressure and heart rate lower, but it keeps you from having the effects of a thyroid storm (a malignant acceleration of
heart rate, blood pressure,
and body temp that can result in brain damage, a
heart attack, or a stroke).
Also, when the time comes for you to go off of it, you should taper over a 2-4 week period. (Eg. Week one-take 1/2 dose each day; Week #2 take 1/2 dose every other day, etc.