Parathyroid surgery may cause hoarseness to occur. Hoarseness after parathyroid surgery is mainly caused by damage to the recurrent laryngeal nerve during surgery. If a patient develops a localized hematoma after surgery, which causes compression of the recurrent laryngeal nerve, hoarseness may occur. This kind of hoarseness caused by compression of the recurrent laryngeal nerve can usually be recovered. Hoarseness can also be caused by damage to the recurrent laryngeal nerve as a result of improper operation by the surgeon during surgery. Hoarseness caused by damage to the recurrent laryngeal nerve can be recovered when the damage is small and can be treated with medications such as vitamin B1 and methylcobalamin; however, if the recurrent laryngeal nerve is disconnected, it is usually impossible to fully recover. If you feel unwell after parathyroid surgery, you should go to the hospital in time for examination and treatment.