What formulation of zinc has been found effective in treating the symptoms common cold?

Zinc acetate lozenges have been found effective in reducing the duration and severity of symptoms of the common cold when taken within 24 hours of the onset of symptoms. The optimal dose appears to be 10-15 mg of zinc acetate taken every 2-3 hours for up to 5 days. It is important to note that zinc lozenges should not be taken for more than 5 days, as this can lead to side effects such as nausea and stomach upset. Additionally, zinc lozenges should not be taken by individuals with certain medical conditions, such as kidney disease or a weakened immune system.