Zinc supplements are commonly used to boost the immune system to shorten the duration of the common cold. They are most effective when used at the onset of symptoms. Some popular brands of zinc supplements are Zicam and Cold-Eeze.
Zinc supplements come in a variety of forms. Cold-Eeze® comes in lozenges and tablets, as well as lollipops and gumballs geared towards children. Zicam® can be found in nasal swabs and gels, an oral spray, and chewable and rapid melt tablets. Zinc must be delivered to the mucosal surface in order to fight a cold, so conventional pills would not be effective.
The active ingredient in zinc supplements used to treat the common cold is zinc gluconate, which has been shown in clinical trials to shorten the duration of cold symptoms. Many users of zinc supplements also experience a reduction in the severity of cold symptoms. Finally, clinical trials have shown zinc supplements to reduce the annual frequency of colds when taken on a regular basis. Cold-Eeze uses a proprietary formula called zinc gluconate glycine, which combines the amino acid glycine with zinc gluconate to make the latter more palatable and stable.
Zinc supplements are not always effective. Generally, they must be used at the onset of a cold and may not be any help once symptoms have already become "full-blown." Zinc gluconate is the only form of zinc shown to be effective in aiding the immune system in clinical trials; though other types of zinc are occasionally used in cold supplements, they have not been clinically proven to provide any relief.
Zinc supplements work against the rhinovirus, which is responsible for 80% of colds. They are not effective against other types of cold or against flu or allergy symptoms. Since zinc gluconate has a positive molecular charge and the rhinovirus has a negative molecular charge, the zinc ions in cold supplements are attracted to the rhinovirus and become attached to it, preventing the virus from being able to reproduce properly.
Do not consume citrus fruits or juices for half an hour before or after taking zinc, as they will interfere with the supplements. Zinc supplements may cause minor discomfort if taken on an empty stomach. Make sure to continue taking zinc until all of your cold symptoms are gone to make sure that the rhinovirus does not return to full strength. Consult a doctor before taking zinc supplements if you are currently on antibiotics, as zinc may reduce their effectiveness.