Voiceover actors need healthy voices, but they, ike everyone else, occasionally get sick. Here are some home remedies for kicking a cold. References:
http://www.realage.com/cold-and-flu/10-cold-and-flu-remedies#fbIndex1
http://health.howstuffworks.com/wellness/natural-medicine/home-remedies/home-remedies-for-sore-throat.htm
