Most of my reading states that most cold and flu medications are safe. That being said, they do say it's better to go with a medicine that has one ingredient and suppresses one symptom than to go with a medication with multiple ingredients. The less ingredients, the better. This medicine here includes doxylamine, which can cause baby to be a little drowsy. Doxylamine can cause supply issues though. It's not uncommon at all for any antihistamine to decrease milk supply in breastfeeding mothers.