cold meds & bfing
While cold medications can often be considered "safe" while breastfeeding (ie. may not harm the baby), they may not actually be beneficial to breastfeeding itself. If the med contains pseudoephedrine (Sudafed, Actifed and many other decongestants), studies have shown this drug to reduce milk volume significantly. The reason for this is that the drug's purpose is to "dry up" nasal secretions, and in so doing, tends to dry up other fluids in the body - and in the case of a breastfeeding mother, this could mean a reduced milk supply. A sudden drop in supply could trigger abrupt weaning in a young infant - not likely a situation you'd want to deal with on top of having a nasty cold!
Rani posted a great med chart, but if you are looking for more info, I would recommend "Medications & Mothers' Milk", by Thomas Hale. Any lactation consultant or La Leche League Leader would have a copy.