This is a tough one. Zinc is a mineral that may have antiviral properties. Some studies suggest that zinc can reduce the length and severity of a cold if you take it within the first 24 hours of a disease. But some people have criticized those studies and others haven’t found an association. The Mayo Clinic does not recommend the use of zinc to treat colds, or any other virus. If you do take zinc, be sure not to take too much, and avoid zinc nasal sprays, which can cause nerve damage and make you permanently lose your sense of smell.