Eugenol is a thyroid hormone drug, if the dosage is appropriate, there can be no adverse reactions, if overdose, it can cause tachycardia, palpitations, angina, arrhythmia, headache, nervousness, excitement and restlessness, insomnia, fear of heat, fever, diarrhea, vomiting, weight loss and other symptoms similar to hyperthyroidism, reducing the dosage or stopping the drug can make all the symptoms disappear. The side effects are as follows: 1. Allergic reactions caused by pure thyroid hormone preparations were first reported in 1986, so allergies caused by this class of drugs also exist; 2. If T4 is used continuously, even if there is no local neurological deficit, there will be headache and edema of the optic nerve papillae on both sides; 4. Acute thyrotoxicosis may lead to clinical thyroid disease syndrome outbreak and even death, but in general, overdose will only result in temporary hyperthyroidism; elderly patients are more sensitive to thyroid hormone, and those over 60 years of age will have a greater need for thyroid hormone replacement. In some cases, thyroid hormone should be used with caution, such as patients with cardiovascular diseases, including angina pectoris, atherosclerosis, coronary artery disease, hypertension, etc. Secondly, for patients with long duration and severe hypothyroidism or mucinous edema, these drugs should be used with caution, starting with small doses and slowly increasing to physiological doses. Patients with hypopituitarism or adrenocortical insufficiency should first use corticosteroids and wait for normal adrenocortical function before using thyroid hormone drugs. In patients with goiter, the secretion of thyroxine is always maintained within the normal range. Due to the accumulation of endogenous thyroxine, a rather small amount of exogenous hormones can cause hyperthyroidism due to an excess of thyroxine.