Betalock drug name is metoprolol tartrate, after taking it usually does not affect the results of thyroid function test, it is recommended to take the drug regularly under the guidance of the doctor. Metoprolol tartrate belongs to the β-blocker, can selectively reduce the excitability of sympathetic nerves, clinically used in the treatment of hyperthyroidism, can block the toxic effect of excess thyroxine on the heart, can control the symptoms of hyperthyroidism faster, generally do not need to stop the drug before the thyroid function test, will not affect the results of the thyroid function test. Contraindications are shock, sick sinus node syndrome, high degree of atrioventricular block, acute myocardial failure, bradycardia, and bronchial asthma. Prolonged use may cause adverse reactions such as heart rate slowing, fatigue, abdominal pain, nausea, worsening of heart failure, etc. If any of these symptoms appear, you should consult a doctor promptly to avoid irreversible damage. It is recommended that the medication be used reasonably under the guidance of a doctor.