Many cold medications are safe for breastfeeding. So little of any medication a mama takes gets into her milk. Where did I see a chart of common medicines that were safe while breastfeeding . . . oh! It was the Sears Baby Book. Hold please while I look it up . . . .
The Sears' give the "green light" to antihistamines and decongestants, as well as ordinary OTC pain killers like acetaminaphen and ibuprofen, if you're achy or feverish.
If you don't want to take OTC medications, you can have warm soup or tea, use a neti pot, set up a humidifier in your room, etc. and snuggle in bed with your baby!
Feel better soon!
Catherine, mama to Preschooler Girl 9/08, and Toddler Boy 3/11