The active ingredient of Eugenol is levothyroxine (L-T4), which is mainly used for supplementation and replacement therapy of Hashimoto’s thyroiditis, post-operative thyroid cancer, and hypothyroidism caused by various reasons, and is recommended to be taken in the morning on an empty stomach. However, it is clinically found that individual patients have taken a lot of Eugenol but the TSH level is still not well suppressed. At this time, we should consider the following points: 1, do not store eugenol more than 25 ℃, once encountered a long-term treatment of eugenol hypothyroidism patients, the disease is well controlled, but once the summer its thyroid function indicators fluctuate greatly, after repeated inquiries, only to find that his drugs in the bedroom, due to high temperature led to drug failure and deterioration. 2. The recommended time to take Eugenol is early in the morning on an empty stomach, because it is more in line with the circadian rhythm of thyroid hormones. Breakfast can be eaten 30 minutes after taking the medication, otherwise taking it with food may affect the absorption of Eugenol. Generally speaking, the peak is reached after taking Eugenol 5-6h. Nowadays, many young people wake up very late but need to solve breakfast before going to work, in this case, taking the medication before going to bed may be the best choice. 3, Eugenol should be avoided with such foods as grapefruit, soy, strong coffee, milk and high fiber diet, because these diets can affect the absorption of Eugenol. I met a patient who had poor results with Eugenol, and finally found out that the patient must drink soy milk every morning. After informing her of the effect of soy milk on the drug, she never drank it in the morning again, and the indicators of thyroid function were normal. 4. Some drugs can affect the absorption of eugenol. Such as abciximide and colestipol, aluminum thioglycollate, antacid aluminum hydroxide, calcium tablets, H2 receptor blockers and proton pump inhibitors ranitidine and loxacor, etc., because these drugs can form insoluble complexes with L-T4 and prevent the absorption of eugenol. Therefore, it is recommended that Eugenol should be taken at least 4h before taking the above drugs. 5.Some drugs can accelerate the metabolism of eugenol and lead to the decrease of blood concentration of eugenol in the body, such as barbiturate, phenytoin sodium, carbamazepine, rifampin and other drugs with liver enzyme-inducing effect can accelerate the metabolism of L-T4 and increase the liver clearance rate, leading to the shortening of the action time in the body and the decrease of blood concentration. Patients are advised to increase the dosage of Eugenol when taking these drugs at the same time. It generally takes 4-6 weeks to re-establish the hypothalamic-pituitary-thyroid axis balance after adjustment of Eugenol. Therefore, at the beginning of treatment, thyroid is measured every 4-6 weeks, and then the dosage of Eugenol is adjusted according to the test results until the treatment goal is reached. If the treatment does not reach the target, the reasons should be carefully searched, such as whether the patient is informed of the correct time and precautions to take the medication, and whether there are any conditions that affect the absorption of the medication, one by one.