Zinc for colds: when is it effective and when is it harmful

Zinc may help shorten the duration of a cold if used within the first 24 hours of symptom appearance, but it does not guarantee prevention. Its effectiveness depends on the timing and method of use, so it is advisable to consult a doctor before taking it to avoid side effects such as stomach upset or copper deficiency, especially when used excessively. Additionally, nasal zinc sprays should be avoided as they can lead to permanent loss of the sense of smell. Supplements should be used cautiously and not exceed the recommended doses to ensure safe and effective benefit.