A red spot on head under hair, medically known as a "nevus flammeus," is a benign birthmark consisting of small, widened blood vessels. These spots are common in newborns and fade over time, but some may persist into adulthood.
Red spots on the head under the hair are usually harmless and do not require treatment. However, it is important to monitor them for any changes in size, shape, or color, as this could indicate a more serious condition.