8-month-old baby always shaking his head, may be a normal physiological phenomenon, such as curiosity, and secondly may be related to vitamin D deficiency, calcium deficiency, eczema and other factors. 1. Physiological factors: 8-month-old babies always shake their heads, may be more interested in this action, curious, usually not accompanied by other adverse reactions, you can observe the follow-up. 2. Calcium deficiency: the baby always shaking his head may be related to the body vitamin D, calcium deficiency, but also accompanied by excessive sweating, occipital baldness. 3. Eczema: the baby appeared above, may be related to eczema, because eczema will cause the baby to appear localized itching, the baby may use head shaking way to relieve. 8 months old baby always shaking his head may have other reasons, it is recommended to go to the hospital in time to carry out relevant examinations, clear causes and active treatment.