If there's one thing that's inevitable each season, it's a case of the sniffles. There's no bypassing colds and the flu—both are respiratory illnesses caused by viruses, explains Pritish Tosh, M.D., an infectious disease physician at the Mayo Clinic—but there are ways to bolster your body's immune system.

To effectively ward off this season's sicknesses—without holing up in your house—use these preemptive tips.