According to a pharmacist I know on another site you can take Sudafed with pseudoephedrine, but you have to use it very sparingly because it can affect your milk supply. I have used it with no bad effects but my dd was over 1yr.
This is from Kellymom
"Mom's use of many forms of Sudafed, Dimetapp and Actifed are considered to be safe for the breastfed baby, but always check the active ingredients, as there are many versions of these medications.
Sudafed (pseudoephedrine, a decongestant) and Actifed (pseudoephedrine plus triprolidine, an antihistamine) are reported safe for baby, and both pseudoephedrine and triprolidine are approved by the AAP for use in nursing moms and pass into breastmilk in minimal amounts.
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:"