Is hair dye safe while breastfeeding?

What does the evidence say about hair dye while breastfeeding?

1. When hair coloring products are used as directed, only a small amount of dye is absorbed through unbroken, healthy scalp skin, and it's unlikely that large amounts of hair-product chemicals would reach breast milk since only small amounts enter the bloodstream in the first place. 1
2. The technical research behind that guidance includes studies measuring how metals like lead and cadmium, sometimes found in hair dye and hair care products, show up in breast milk, part of the evidence base used to estimate how much a nursing infant might be exposed to as a result. 2
3. Permanent hair dye is built on p-phenylenediamine and related coupling agents that can penetrate skin and be absorbed through the airway during application, and a research review notes that endocrine-disrupting compounds in hair products can move from the bloodstream into breast milk through passive diffusion. 3
4. That same review points to case-control studies that identified maternal hair dye use, in the month before pregnancy, during pregnancy, or during breastfeeding, as a factor associated with certain rare childhood cancers including leukemia and germ cell tumors, though these findings come from studies asking mothers to recall past exposure rather than from tracking exposure in real time. 3
5. A separate nested case-control study of over 6,000 women found that hair dye use before conception was associated with about 70% higher odds of a low-birth-weight infant, though the authors cautioned that the study didn't capture how often or which specific products were used and called the overall evidence base on hair dye and birth weight limited. 4

How hair dye changes by nursing stage

• Early weeks. In the early postpartum weeks, some people wait until postpartum hair shedding settles down or hormones stabilize before coloring, though there's no medical requirement to wait. If you do dye your hair now, keep your newborn out of the room during application and rinse well before close skin-to-skin contact.
• Established nursing. Once breastfeeding is established, hair dye is one of the lower-concern cosmetic exposures. MotherToBaby's guidance is that only a small amount is absorbed through the scalp and it's unlikely to reach milk in meaningful amounts when products are used as directed.
• Weaning. The same precautions, ventilation, gloves, and avoiding a broken or irritated scalp, apply whether you're a few months or over a year into breastfeeding. There's no point at which the guidance changes based on how long you've been nursing.