Adverse effects of lozenges include bad taste and nausea. The human rhinovirus – the most common viral pathogen in humans – is the predominant cause of the common cold. The hypothesized mechanism of action by which zinc reduces the severity and/or duration of cold symptoms is the suppression of nasal inflammation and the direct inhibition of rhinoviral receptor binding and rhinoviral replication in the nasal mucosa. Zinc has been known for many years to have an effect on cold viruses in the laboratory. Some lozenge formulations do not contain enough zinc to effectively reduce the lengths of colds; some of them contain ingredients that bind zinc, like citric acid, which prevent the zinc from working.