After thyroid surgery, many patients need to take eugenol (also known as levothyroxine sodium tablets, which is not related to thyroid lobe removal), but some patients do not know enough about the purpose of taking the medication, have great concerns about the side effects of eugenol, and find it troublesome to take the medication every day. Ordinary thyroxine tablets are a mixture of T3 and T4, mostly derived from pig thyroid extracts, and are therefore affected by the ability of pigs to synthesize thyroid hormones from eating iodine. Euthyroxine is a synthetic levothyroxine tablet, i.e. T4, with stable potency. The human body has both T3 and T4, but the vast majority of T3, is converted from T4 by deiodinase, and free T3 is five times more active than free T4. Patients with thyroid cancer take more oral eugenol, which inhibits thyrotropin (TSH) and reduces recurrence through a negative feedback approach, so it is thought that it does not directly increase T3 in the body much, but only T4, resulting in fewer side effects. The T3 half-life is 1.5 days, while T4 is 6-7 days. The blood concentration obtained from taking eugenol is certainly more stable than that of ordinary thyroxine tablets, and patients have better compliance in taking the medication, so ordinary thyroxine tablets are not used much at present. There are many patients with benign thyroid nodules that do not require surgery, and their hopes of using eugenol or even herbal medicine to inhibit the growth of the nodules are mostly unfulfilled. For this group of patients, the best approach is to have a semi-annual ultrasound examination and to operate only if cancer or enlargement is suspected. For some patients with benign diseases such as thyroid adenoma or nodular goiter after surgery, they may take Eugenol, which can be stopped if the TSH is controlled around 2. After thyroid cancer surgery, oral euthyroxine, in addition to replacement therapy is more important to inhibit recurrence and metastasis or progression of the disease, such as making TSH less than 0.1 (complete inhibition, especially for bone and lung metastasis or surgical resection cannot be complete), and also emphasize the selection of the best amount of inhibitor according to individual patient’s condition (heart, osteoporosis), so that TSH is slightly less than the low limit of normal value or slightly above the low limit of normal value, especially Especially for patients with low-risk thyroid cancer (e.g. clean tumor removal, undetectable thyroglobulin, negative systemic iodine scan) and poor cardiac function in their old age, it is not advisable to take high dose of eugenol to oversuppress, so as not to produce large side effects. Of course, the patient’s weight and the amount of remaining thyroid tissue affect the dose of eugenol required. It is important to review the thyroid function and adjust the dose of Eugenol according to the thyroid function. The results of blood tests after 1 month of regular medication usually indicate a stable thyroid hormone status in the body. Levothyroxine sodium tablets should be taken half an hour before breakfast, on an empty stomach, with a one-day dose delivered with water for the highest potency. In elderly patients, patients with coronary artery disease, and patients with severe or chronic hypothyroidism, special attention should be paid to choosing a lower initial dose at the beginning of treatment with thyroxine (endocrinologists even sometimes start with a quarter tablet of 12.5 micrograms) and slowly increasing the dose (a quarter tablet) with regular monitoring of blood thyroxine levels. Note that patients on long-term eugenol TSH suppression therapy after thyroid cancer surgery need to take calcium supplements in moderation to avoid osteoporosis.