Medicines and Breastfeeding
Although almost all medicines pass into your milk in small amounts, most medicines have no effect on the baby and are compatible with continuing to breastfeed. The list of medicines that you should not use while breastfeeding is very short. Discuss any medicines you are using with your doctor and also ask before you start using new medicines, including prescription and over-the-counter drugs, vitamins, and dietary or herbal supplements. For some women with chronic health problems, stopping a medicine can be more dangerous than the effects it will have on the breastfed baby.
American Academy of Pediatrics has more detailed information on this topic in the publication, The Transfer of Drugs and Other Chemicals Into Human Milk. You can also learn more from Medications and Mothers’ Milk, a book by Thomas Hale, found in bookstores and libraries.