A throbbing pain in the left side of the head may be caused by scalp neuralgia, trigeminal neuralgia, migraine and other reasons. 1. Scalp neuralgia: Scalp neuralgia may occur when the head is cold, overstressed, or sleep deprived, leading to throbbing pain in the superficial region of the head, which may occur unilaterally or in the whole head. 2. Trigeminal neuralgia: Intracranial vascular malformations and infections may damage the trigeminal nerve, resulting in trigeminal neuralgia. When the left trigeminal nerve is damaged, the left side of the head may have throbbing pain, and the pain is mostly intense, pinprick-like, tear-like. 3. Migraine: usually occurs when overworked and under stress. It is characterized by recurring headaches, unilateral throbbing, often accompanied by nausea, vomiting, photophobia and other symptoms. It is recommended that when the left side of the head nerve throbbing pain, go to the regular hospital in time, to clarify the cause, under the guidance of the doctor for standardized treatment, so as not to delay the condition.