The efficacy of levothyroxine tablets is closely related to the absorption rate. The absorption rate of levothyroxine tablets taken on an empty stomach is 80% and 64% respectively when compared with those taken with meals. The method of taking levothyroxine from the best to the worst is: 1 hour before breakfast > before going to bed > half an hour before breakfast > taken with breakfast Therefore, it is recommended: 1 hour before breakfast, or before going to bed (no meal or snack 3 hours before taking the drug) If you want to eat trace element complex, calcium carbonate, iron, etc., the recommended interval is more than 4 hours.