Headache after washing head may be caused with migraine, cold, cerebral blood supply insufficiency and other reasons, need to be further differential diagnosis by the doctor. 1. Migraine: If the temperature of the water used for washing hair is low, it can trigger the onset of migraine and headache after washing hair. 2. Colds: If you get cold during or after shampooing, it can cause colds and headaches. 3. Insufficient blood supply to the brain: a low-hanging or incorrect posture may affect the blood supply to the brain and cause a headache after shampooing. It is recommended that people with headaches after washing their heads go to a regular hospital in time to clarify the cause, and if treatment is needed, it should be standardized under the guidance of a doctor to avoid delaying the condition.