Women who are breastfeeding should generally not color their hair, and if they do, they are not allowed to breastfeed normally. Hair dyes usually contain many harmful chemicals, especially phenylenediamine as a coloring agent, which is internationally recognized as a carcinogen. During the process of hair coloring these harmful substances are easily absorbed into the blood circulation through the blood vessels of the scalp, affecting the quality of breast milk and thus the health of the breastfeeding child. In addition, hair dyes usually have a strong odor, so if you breastfeed soon after dyeing your hair, it is easy to irritate your baby’s respiratory tract, causing allergies or coughing. Therefore, breastfeeding mothers should not dye their hair, and if they must dye their hair, they should wait for at least one week for the harmful substances to be metabolized or for the smell to dissipate before breastfeeding. Therefore, for the sake of the baby’s health, mothers should avoid coloring their hair while breastfeeding and reduce the use of cosmetics.