what is levothyroxine and side effects
Levothyroxine Side Effects Heart palpitations, difficulty breathing, and insomnia are among the possible side effects of levothyroxine. You should report any potential side effect to your healthcare provider right away, as it may be a symptom of hyperthyroidism and an indication that your levothyroxine dosage is too high.
These side effects may include: 1  Feeling hot all the time and increased sweating. 2  Fever. 3  An increased appetite, along with weight loss. 4  Heart palpitations. 5  A rapid heart rate (tachycardia) 6  Heart failure, chest pain, or a heart attack. 7  Difficult or painful breathing. 8  Insomnia (see Levothyroxine and Insomnia) 9  Emotional changes.