The more common side effects of the medication for hypothyroidism, which refers to levothyroxine tablets, are that it leads to an increase in heart rate, induces an attack of coronary heart disease, and leads to osteoporosis. These side effects are mainly due to inappropriate dosage of the drug, i.e. overdose of levothyroxine tablets. If the dosage of levothyroxine tablets is within the normal range and the patient’s thyroid function is normal, the above mentioned side effects will not occur. Therefore, when patients with hypothyroidism take levothyroxine tablets for oral replacement therapy, they must pay attention to monitoring the changes in thyroid function, and the replacement dose of the drug should not be too much or too little.