It was George Eby who first reported that zinc acetate (not other forms of zinc) in a lozenge helps to shorten the duration of the common cold. [Medical Hypotheses 2010] Now, a vitamin C skeptic has declared zinc lozenges to be effective, shortening a cold by nearly 3 days. Most bouts last 7-10 days. [British Journal Pharmacology July 5, 2016] Forget Theraflu. Forget Nyquil. Effective dose of zinc acetate is ~100 mg. Other forms of zinc not so good.