The common cold is often caused by the rhinovirus. It is one of the most widespread illnesses and is a leading cause of visits to the doctor and absence from school and work. Complications of the common cold include ear infection, sinusitis and exacerbations of reactive airway diseases. There is no proven treatment for the common cold.  Zinc appears to interfere with the replication of rhinoviruses.

Zinc inhibits replication of the virus and has been tested in trials for treatment of the common cold. In 18 randomised controlled trials with 1781 participants of all age groups, zinc was compared with placebo (no zinc). Zinc (lozenges or syrup) reduces the average duration of the common cold in healthy people, when taken within 24 hours of onset of symptoms.