Can zinc prevent a cold or shorten its duration?
Zinc has no clear role in routine cold prevention. A review suggests it may shorten a cold by about two days on average, but certainty is low and results vary. Nausea and unpleasant taste can occur; avoid intranasal zinc products.
Details
An average is not a guarantee
Trials used different zinc salts, doses and start times. A possible benefit does not mean every tablet is suitable or justify taking high doses throughout winter.
Why avoid prolonged high intake?
Excess zinc can cause copper deficiency and other health problems. It can also interfere with absorption of some antibiotics. Ask a pharmacist whether it is appropriate and how doses should be separated.
Avoid nasal zinc
Intranasal zinc has been associated with loss of smell. Check cold-product ingredients and seek advice for children or pregnancy. Persistent symptoms or breathing difficulty needs assessment of the cause rather than additional supplements.
Related reading: Does vitamin C prevent colds or help after symptoms begin?.