If you are breastfeedingand are considering taking any medications, it is very important to be sure that you take medicine that is compatible with breastfeeding. Some medications can be harmful to your baby's health, while others won't affect him physically but may cause a drop in your milk supply.
Finding Out Which Medications Are Safe
Possibly the best source for information on how medications can influence breast milk is a board certified lactation consultant. Lactation consultants specialize in human milk production, and more than likely will be able to give you specific information regarding various medications. Alternatively, you could also speak with your family doctor or your obstetrician.
Common Medications Known to Affect Breast Milk Supply
The big disclaimer that you need to understand, some women's milk supply may be inhibited by certain medications more so than others. You really can't know for certain how a medication will affect you. If you are experiencing issues with milk supply or if you are even mildly concerned about it, then you may want to be more cautious about which medications you take.
Some fairly common drugs which may cause a drop in supply are birth control pills which contain estrogen and pseudoephedrine, a decongestant used to treat nasal, sinus, and eustachian tube congestion. Pseudoephedrine can be found as a single ingredient or in combination with other drugs like antihistimines, guaifenesin, dextromethorphan, paracetamol (acetaminophen), and/or NSAIDs (e.g., aspirin, ibuprofen, etc.).
"Supply Friendly" Breastfeeding Medications and Alternatives
There are progestin birth control pills which are an option for breastfeeding moms who desire to take oral birth control pill. As far as pseudoephedrine, which has also been shown to cause as much as a 24% drop in milk supply, though other cold medicines (such as antihistimines) have been suspected of causing a drop in breast milk supply, there are no studies which support this. If you are concerned about your supply, speak with your doctor about supply friendly medications or natural remedies for treating colds and congestion.
Table 6: Maternal Medication Usually Compatible With Breast-Feeding, from the AAP Policy Statement The Transfer of Drugs and Other Chemicals Into Human Milk, revised September 2001.
Medications and Mothers' Milk (2004 edition) by Thomas Hale, Ph.D.