Dyeing hair is harmful to hair and even the whole health. It is recommended that you dye your hair at least once every six months. The principle of hair dyeing is mainly to cause the color change inside the hair through the combination of oxidant and dye. The chemicals used are toxic to human body, including substances such as p-phenylenediamine, which on the one hand will cause damage to hair quality, on the other hand, it will stimulate scalp and cause allergic dermatitis.
If the hair dye touches the scalp, it can enter the human body after being absorbed by the scalp. If the amount is relatively large and lasts for a long time, it will cause visceral damage and even cancer. Studies have shown that hair dyes are related to leukemia, bladder cancer and kidney cancer, so frequent hair dyeing is generally not recommended. It is necessary to provide the human body with time for buffering, metabolism and repair at regular intervals. Otherwise, frequent hair dyeing, too much toxins entering the body and too long accumulation time may cause serious harm. Therefore, in general, it is safer and more secure to dye your hair at least once every six months.