Check us out on Men's Journal. ""Tea tree oil couldn't be guaranteed to ward off flus or colds, but it acts similarly to a vapor rub, getting into the airways when you breathe in the scent," says Diana Duncan, certified naturopathic doctor at Bastyr University. "And because it has broad antibacterial-antiviral action, it could potentially kill illness-causing bugs hanging out in your airways." By using a tea tree-based beard oil or balm, you can reinforce your facial hair with some potential cold and flu-fighting powers, not unlike drinking plenty of fluids and eating foods high in vitamin C."