Although thyroid surgery is not a very difficult major surgery, there are often some very troubling post-operative complications. Many patients are often so confident before surgery that they do not seriously consider the occurrence of post-operative complications. Once they occur, they are caught off guard and affect their mood and life. It is important to carefully understand these possible complications before surgery to help us decide on the type of surgery and choose the best treatment facility and surgeon to avoid post-operative complications as much as possible. There are two main complications that patients complain of after thyroid surgery: postoperative hoarseness (damage to the recurrent laryngeal nerve) and postoperative sensory numbness and cramping (parathyroid dysfunction). A brief description of these two complications is as follows. 1. Postoperative hoarseness is usually caused by surgery affecting or damaging the recurrent laryngeal nerve. The recurrent laryngeal nerve innervates the muscle movements of the vocal cords and regulates the opening and closing of the vocal chambers. Damage to the laryngeal nerve after thyroid surgery can cause vocal fold movement disorder, making the voice weak and hoarse. If the nerve is damaged on both sides, it can cause narrowing of the vocal cords causing difficulty in inspiration. The chance of occurrence is not uncommon, with reports ranging from 1%-16%. The condition of the patient’s thyroid disease itself and the surgical operation are the main factors contributing to postoperative hoarseness. For patients at high risk, a detailed preoperative discussion with the surgeon about the surgical approach is required. Otherwise, the quality of life and work will be seriously affected if it occurs. If the problem of postoperative hoarseness does occur, the relevant causes can be clarified through examination and the necessary remedial measures can be discussed with the doctor. 2. Post-operative numbness and cramping are usually caused by the surgery affecting the parathyroid glands. The parathyroid gland is another endocrine gland close to the thyroid gland that secretes parathyroid hormone and is involved in regulating blood calcium levels. If the parathyroid gland is removed during thyroid surgery, it will affect the stability of serum calcium levels, causing sensory numbness and, in severe cases, hypocalcemic cramps. This complication is very common, and my observation is that one third of patients will have complaints of sensory numbness after surgery. However, the vast majority of patients have only a transient condition and only a very small number of patients have a long-term condition. The former may be a temporary hypofunction caused by the blood supply to the parathyroid glands being affected during the surgery, which will recover quickly within 3 days. In the latter case, the parathyroid glands may have been removed causing long-term hypofunction. If this is the case long-term calcium and vitamin supplements will be required. The surgeon will usually assess the chance of this complication and if it is high, prevention and treatment will be discussed in detail with the patient before surgery. Understanding the common complications associated with thyroid surgery can help patients make better choices of providers and work with their doctors to provide proactive prevention and treatment remedies.