You always hear: Green or yellow mucus means it's a bacterial infection.
The reality: Nasal discharge (otherwise known as snot) is not a reliable way to diagnose the type of infection. Both viruses and bacteria trigger the same immune response: White blood cells shoot to the respiratory tract to fight off the germy invaders. The extra mucus is simply the debris left over from battle. That said, it can provide two valuable clues to the severity of the illness: If nasal discharge gets thicker and your baby becomes sicker, or if discharge begins seeping from her eyes as well, it's time to see the doctor. Babies with the eye-nose combo usually have both a sinus and an ear infection and likely need antibiotics to treat them.
You always hear: Cool-mist humidifiers are better than steam vaporizers.
The reality: Both can ease your baby's symptoms. The one you choose really depends on which you prefer. The newer ultrasonic cold-mist humidifiers produce a very fine mist that can penetrate deeper into clogged breathing passages for a more effective "steam clean." They're also more hygienic than the old drum-style humidifiers, which can become a reservoir for germs when they're not disinfected regularly (and they rarely are; who has the time?).
My preference for winter is a hot-mist vaporizer, which gives you a double-whammy cold remedy. First, vaporizers produce a sterile steam, which means you don't have to worry about possibly spewing more germs into your already-sick baby's room. And because they also provide another heat source, at night you can turn down the central heating, which can dry the air, thickening mucus further. Of course, steam vaporizers can cause burns if they're accidentally tipped over, so always be sure to keep yours well out of the baby's reach.
William Sears, M.D., is a contributing editor.