Hair not washed for a long time may lead to scalp hair dirt, scalp inflammation, hair loss and so on. 1. Scalp hair dirt: long time without washing hair, dust in the air and scalp secretions and other stimulation of the scalp and hair to produce a large amount of dirt stays on the scalp and hair, so that the hair becomes greasy, bunching, emitting a bad smell, etc., affecting physical and mental health. 2. Scalp inflammation: long-term unwashed hair, scalp dirt stimulates the scalp inflammatory reaction, combined with a variety of bacterial and parasitic infections, such as scalp folliculitis, scalp fungal infections, head lice, mites and so on. 3. Hair loss: Long-term unwashed hair, scalp bacteria, dirt, sebaceous secretion secretion clogging scalp pores, resulting in hair loss. It is recommended to develop good living habits, pay attention to hygiene, when scalp diseases and other adverse reactions occur, it is recommended to actively go to the hospital.