Normally, you can't tell when one nostril is taking a rest. While mucus is clear, you've just got a cold or allergies. When mucus turns yellow or green, you have a bacterial infection. If it doesn't begin to resolve itself after about five days, it's time to see a doctor. In addition to drinking lots of fluids, a hot shower and vaporizer can help keep membranes moist.
Hot soups increase blood flow to the throat, which helps fight off a sore throat.