Zinc Supplementation During Cold and Flu Season
Zinc should not be taken daily during cold and flu season as a preventive measure; instead, take 75 mg/day of zinc acetate or zinc gluconate lozenges only when cold symptoms begin, starting within 24 hours of symptom onset. 1
When to Start Zinc Supplementation
The evidence clearly distinguishes between prevention and treatment:
- For prevention during cold season: There is insufficient evidence to recommend daily zinc supplementation in healthy adults simply because it's cold and flu season 1
- For active cold treatment: Begin zinc lozenges at ≥75 mg/day immediately when cold symptoms start, ideally within 24 hours of symptom onset 2, 1
Recommended Dosing and Formulation
When you do develop cold symptoms, the specific protocol matters:
- Dose: ≥75 mg/day of elemental zinc 2, 1
- Formulation: Zinc acetate or zinc gluconate lozenges specifically (not other zinc formulations) 1
- Timing: One lozenge every 2 hours while awake 3
- Duration: Continue throughout the symptomatic period 4
Expected Benefits
When used correctly at symptom onset, zinc provides measurable benefits:
- Reduces cold duration by approximately 2-3 days (median 4.4 days vs 7.6 days with placebo) 3, 5
- Decreases severity of symptoms including cough, nasal congestion, nasal drainage, and sore throat 4, 3
- Reduces the proportion of patients still symptomatic after 7 days of treatment 4
Side Effects to Counsel Patients About
The benefits must be weighed against common adverse effects:
- Bad taste: Occurs in approximately 80% of patients (vs 30% with placebo) 3
- Nausea: Affects about 20% of patients (vs 4% with placebo) 3
- Overall adverse events are higher in the zinc group, though generally self-limiting 1, 4
Common Pitfalls to Avoid
- Don't recommend daily zinc throughout cold season: The evidence supports treatment, not prevention in healthy adults 1
- Don't delay initiation: Zinc must be started within 24 hours of symptom onset for maximum benefit 1
- Don't use inadequate doses: Doses below 75 mg/day have not shown consistent benefit 2, 1
- Don't confuse formulations: The evidence specifically supports zinc acetate or zinc gluconate lozenges, not other zinc preparations 1
Special Population Considerations
- Young children: There is no evidence of effectiveness for zinc lozenges in young children for common cold treatment 6
- Athletes or high-risk individuals: May benefit from ensuring adequate baseline zinc intake through diet or multivitamin supplementation during high-risk periods (autumn/winter), but not high-dose therapeutic zinc 2