Aw, I haven't personally tried collagen while breastfeeding kaya hindi ko masyadong ma-recommend nang may confidence, pero I'd really suggest asking your OB or pedia first bago mag-start ng any supplements, maraming moms sa circle ko na nag-take ng collagen pero gusto nila na alam muna ng doctor kung okay lang talaga habang nagbabayad, especially if sensitive ka or may specific health stuff. Better safe than sorry with breastfeeding kasi everything goes to baby din, no?