Without any reputable studies, it’s hard to say stay away from cosmetics and beauty products when breastfeeding. We do know that artificial fragrances are toxic and should be avoided anyway, but outside of that, it’s sort of a use-your-own-discretion type of thing. Knowing about the aluminum in antiperspirant and having underarm skin so close to breast skin causes many women to avoid that product while nursing. Many mothers also avoid perfumes while their babies are small (breastfeeding or not) since so much skin-to-skin contact happens during that time.
Ultimately, like everything else about motherhood, what you choose to avoid and what you continue to enjoy while nursing your baby is a very personal decision that only a mother can make for herself. By gathering your own information and consulting your trusted medical professional, you’ll have all the knowledge you need to trust your instinct, which will always be right for you and your baby.