Scientists have proved that p-phenylenediamine in hair dye is carcinogenic by animal experiments, but there is not enough evidence in the existing research data to show that hair dye is carcinogenic when used in human body. The occurrence of non-Hodgkin's lymphoma, multiple myeloma, acute leukemia and bladder cancer may be related to the long-term use of ultra-large dose hair dye.

The skin lesions caused by hair dyeing are mainly delayed allergic reactions caused by hair dye sensitization. Usually confined to the contact area, manifested as scalp and facial edema, even involving ears, neck and shoulders, but generally not life-threatening. The incidence of delayed allergic reaction caused by hair dye is about 1/65438+ ten thousand, but the actual incidence may be higher, mostly after self-dyeing.

If you need to dye your hair, be sure to pay attention to the scratches on your scalp. Don't keep your hair clean and dry before dyeing, and don't do special care such as baking oil one week before dyeing. It is best to wash your hair the day before dyeing your hair. First, the oil secreted by the scalp has a protective effect on the scalp. Second, you can avoid accidental scratches when washing your hair. Do not use styling products on the day of dyeing your hair.

Avoid direct contact between hair dye and skin. Before dyeing hair, put the hair dye on the hairline to prevent the hair dye from contaminating the skin and causing harm.

Comb your hair before dyeing it. When dyeing hair, you can massage your head thoroughly with your fingers until the hair dye milk is evenly distributed on each hair. Don't cover or wrap your hair, but let it spread freely until the hair dye is evenly distributed. Please don't overheat when dyeing your hair.

Don't dye your hair repeatedly for three months. The decolorant contained in the hair dye will damage the hair scales, and the damaged hair scales will become fragile and easily broken. If you dye your hair repeatedly within three months, the damaged hair scales will be damaged again and cannot be recovered.