Discomfort and swelling on the left side of the neck is a condition that may first be caused by overexertion. If the patient works with his head down for a long time, causing tension in the neck muscles, this symptom may appear. In addition, long time blowing fan, blowing air conditioning caused by the neck cold, may also appear the symptoms of neck swelling. In addition, if one side of the neck muscles are tense due to prolonged lying during sleep, the neck may also be swollen. Patients suffering from cervical spondylosis are also prone to this symptom. Due to long-term neck strain, osteophytes or cervical disc prolapse, patients suffering from cervical spondylosis can experience pain and swelling in the neck and back, and may experience weakness in the upper limbs, numbness in the fingers, nausea and vomiting. The first thing to do in this case is to pay attention to rest and avoid straining. In addition, appropriate hot compresses can be applied, which can relieve the symptoms of neck discomfort. If the symptoms cannot be relieved, you need to go to the hospital for further examination to clarify the cause.