If an herbal treatment — even in tea form — has an effect, it should be considered a drug. Just because it comes from a plant or another natural source, does not mean it cannot have negative effects on the user. A drug is a drug whether humans or nature makes it, and no drug is totally free of negative side effects. However, almost all drugs are safe while breastfeeding. The real question is: Which is safer, breastfeeding with a tiny amount of drug in your milk (and it is almost always tiny) or giving your baby formula? Without question, with 99.9 percent of all drugs, breastfeeding is safer. But talk to your health care provider about herbal teas and supplements.