A throbbing pain on the back of the left side of the head may be caused by nervousness or localized cold, cervical spondylosis, cerebrovascular lesions, migraine, temporal arteritis and other reasons. 1. Nervousness or localized cold: brain cells lack of rest when staying up late for a long time, nervousness may appear localized throbbing pain; the back side of the head after getting cold leads to scalp vasoconstriction and spasm, resulting in a throbbing pain. 2. Cervical spondylosis: the hyperplasia of cervical vertebrae and intervertebral discs compress and stimulate the adjacent spinal nerve roots, resulting in neurological headaches, which may involve the back of the left side of the head, leading to throbbing pains in this area. 3. Cerebrovascular lesions: decreased elasticity or even rupture of cerebrovascular blood vessels in hypertension, cerebrovascular embolism leading to localized cerebral infarction, etc. may also lead to throbbing pain on the left side of the head. 4. Migraine: this disease may be related to heredity, endocrine abnormality, stress and other factors, manifesting as throbbing pain on one side or both sides of the head that gradually worsens. 5. Temporal arteritis: this disease may be related to autoimmune, age increase, heredity and other factors, patients with inflammatory cell infiltration and immune material deposition in the endothelium of the arteries, resulting in arterial inflammatory lesions, appearing as one or both sides of the temporal region of the pain, which may involve the occipital region. The throbbing pain on the back of the left side of the head may be related to a variety of factors, it is recommended to consult a doctor for a clear diagnosis, and give targeted treatment.