The best advice is to treat only the symptoms that you have, don't go for the big daddy of all cold medicines and buy the cover every symptom you could possibly think of medicine. Stick to what you need and only what you need. So if you're suffering with a stuffy nose, get only stuffy nose medicines. When you're buying medication, even over the counter medication, be sure to read the ingredients.
For coughs and colds:
- over the counter cough drops (as recommended)
- expectorants containing guaifenesin
- cough suppressants with dextromethorphan
- combination guaifenesin/dextromethorphan
What to avoid while pregnant:
- alcoholic preparations (in medications and out)
- Pseudoephedrine and phenylephrine (decogestants) in 1st trimester (data is conflicting). Use in the 2nd and 3rd trimesters is generally acceptable for brief durations when done responsibly.
It's also important to note that all of the comfort care measures are good too, like warm soup, taking a warm bath, napping, massage, sinus rinses, etc. Many times pregnant moms talk about how these were way more helpful than medicine foe them, so consider doing both when you have a cold in pregnancy.