Washing hair with cold water is definitely not good, cold water is easy to catch a cold and also easy to get frostbite, especially in the cold season when washing hair with cold water will cause more harm to the body. Washing your hair with cold water is likely to cause strong vasoconstriction, resulting in a drop in body temperature, which can easily make your body cold and cause a cold, causing serious harm to the health of the patient, and it should also be noted that washing your hair with cold water is not beneficial to your scalp. Washing your hair with cold water may cause the scalp to be poorly cleaned and easily breed bacteria, and washing your hair with cold water, the water temperature is too low will likely stimulate the nerves in the brain, causing trigeminal nerve pain, and if the patient also has a cold, washing your hair with cold water in this case may also aggravate the symptoms of the cold, causing bronchitis or even pneumonia, which is very unhelpful to the patient’s health.