Chicken soup thins the mucous in the lungs, making the mucous easier to expel.
Hot and spicy foods act as expectorants. When you eat these foods regularly, they help thin mucous secretions of colds, asthma, and allergies. Garlic kills the viruses and bacteria associated with the common cold and flu. Drinking plenty of liquids will hydrate the mucous membranes. Viruses thrive in dry environments.