Pain in the left side of the neck is seen in the following cases: First, it is caused by cervical spondylosis, which is more frequent in middle-aged and elderly patients and is associated with bone degeneration, osteophytes, and prolonged chronic strain, and the pain is accompanied by numbness and limitation of activities in the upper limbs. Some patients also present with headache, dizziness, nausea, vomiting, and significant upper extremity weakness, even with limitation of movement, and CT examination can confirm the diagnosis. Physiotherapy methods can make their symptoms better, and surgery is an option if necessary. Secondly, diseases occurring in the thyroid gland, commonly occupying lesions of the thyroid gland, including adenomas, cysts and simple nodular goiter. If the lesions gradually increase in size, there will be local pain and even an obvious feeling of gas pressure. Thyroiditis secondary to upper respiratory tract infection may also be associated with significant neck pain.