A 4-month-old baby suddenly likes to shake his head may be due to physiological factors, head itching, lack of calcium and vitamin D, otitis media causes. 1. Physiological factors: 4-month-old children’s brain function is not fully developed, body control ability is poor, easy to suddenly shake their heads, which is a normal physiological phenomenon. 2. 2. Itchy head. 4-month-old children always lie down, prone to head itching, by shaking the head to relieve itching. 3. lack of calcium and vitamin D. 4-month-old babies do not supplement calcium or vitamin D in time, causing muscle spasm, which leads to crying and other symptoms, may appear to shake their heads. 4. Otitis media. The baby may suffer from otitis media and other ear diseases, causing ear discomfort, thus shaking the head to relieve the discomfort. Baby 4 months suddenly like shaking head may also have other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.