Luckily, it turns out that breast feeding is very different than being pregnant. The placenta is basically a big sieve, it filters out a lot of stuff but since it is non-specific it does allow a lot of stuff to cross over. A lot of the ingredients to avoid while pregnant are because of the timing of the exposure, your baby was busy making organs!
When nursing, the body is pretty specific about what goes into breast milk. It isn’t filtering everything into the breast milk, instead things are much more specific. The timing of exposure (and potential side effects) is just very different once the baby is out! Those organs have been made, and the baby is also just a lot bigger. So, the list of skin care ingredients to avoid while nursing is much shorter than the list of ingredients to avoid while pregnant.
Medications and Nursing
One thing you need to be worried about are your medications. Nursing safety is a bit different than pregnancy safety for medications. Everything should be looked up in a lactation safety book (Medications and Mother’s Milk or Drugs in Pregnancy and Lactation) and discussed with your physician. L1-L3 are considered safe, L4 and above is not safe.
Skin Care Ingredients to Avoid While Nursing
• Retin A/Accutane, Retinoids, Vitamin A: Used topically, Retinoids are a category L3, but orally (as with Accutane) they fall to L4. So, topical is ok, systemic is not. I’d check with your doctor if you’re on anything other than just a basic, over the counter topical retinoid, but those found in skin care products should be fine.
• Hydroquinone: While there is no data on Hydroquinone in humans, it is absorbed and quite water soluble, and based on some pharmacodynamics (the pKa, which is too complicated to get into here as it was a many hour discussion when I was in medical school), it may be trapped in the breast milk if it reaches it. So, it is recommended to avoid. I would include Arbutin with hydroquinone.