Can antibiotics relieve colds?

According to an old wives’ tale, if the mucus from your sinuses becomes green, it’s a sign of a bacterial infection. But in fact the infection could be caused by a virus. The color comes from waste products discharged through the nose, such as dead white blood cells. While most sinus infections clear up on their own, if an infection lasts for more than 10 days, then it’s time to make a doctor’s appointment. But remember: Antibiotics don’t have an effect on viruses!