Milk supply: Pseudoephedrine (Sudafed) may reduce milk supply. Thomas Hale Ph. D., a renowned breastfeeding pharmacologist (Breastfeeding Pharmacology), has recently said that he recommends using caution with Sudafed or any product containing pseudoephedrine:
"Preliminary studies from our laboratories suggest that in some mothers, a significant reduction in milk volume and prolactin levels may result following exposure to pseudoephedrine. While the amount of pseudoephedrine in milk is not clinically relevant, the reduction in milk supply is concerning." (Medications' and Mothers' Milk by Thomas Hale, PhD, 2002 edition, p. 605.)
Dr. Hale was speaking of this study, which is now complete: Aljazaf K, et. al. Pseudoephedrine: effects on milk production in women and estimation of infant exposure via breastmilk. Br J Clin Pharmacol. 2003 Jul;56(1):18-24.
If you do take pseudoephedrine and notice a drop in milk supply (many moms do not, but recent research shows that it can decrease milk supply by as much as 30%), simply stop the medication and take measures to increase milk supply - the problem should resolve fairly quickly.
Be very cautious about taking pseudoephedrine on a regular basis, as it has the potential to permanently decrease your milk supply. Regular use of pseudoephedrine (120 mg/day) has been used to decrease milk production in moms with overproduction, where the usual methods to regulate milk production were not working.