What are side efffects of levothyroxin in 70yo active male?

Levothyroxine: If being prescribed to appropriately replace your own thyroid deficiency or hypothyroidism, none.

Levothyroxine: High heart rate, palpitation, high blood pressure, weight loss if level is too high, weight loss. Weight gain, tiredness if level too low.

None if dose OK: People take levothyroxine to get back something their body normally produces on its own. Thus, if you are taking the right amount for you (usually determined by TSH test), there should be no side effects. Too much thyroid hormone can cause heart pounding, shakiness, shortness of breath, feeling hot. Too little can cause constipation, dry skin, feeling cold. Both can cause wt changes & fatigue.