Zinc is Effective for Treating the Common Cold
Zinc administered as zinc acetate or zinc gluconate lozenges at a dose of ≥75 mg/day and taken within 24 hours of symptom onset significantly reduces the duration of the common cold. 1
Effectiveness of Zinc for Common Cold
- Zinc lozenges taken at appropriate doses can reduce the duration of common cold symptoms by approximately 3 days compared to placebo 2, 3
- When administered within 24 hours of symptom onset, zinc significantly shortens the overall duration of cold symptoms (4.0-4.5 days vs 7.1-8.1 days with placebo) 2, 4
- Zinc treatment specifically reduces the duration of cough (2.1-3.1 days vs 5.0-6.3 days), nasal discharge (3.0-4.1 days vs 4.5-5.8 days), and nasal congestion (4.0 days vs 6.0 days) 2, 3, 4
Recommended Dosing and Formulation
- For optimal effectiveness, zinc should be administered as zinc acetate or zinc gluconate lozenges at a dose of ≥75 mg/day 1
- Treatment should begin within 24 hours of symptom onset for maximum benefit 1, 2
- Lozenges should be taken every 2-3 hours while awake throughout the duration of cold symptoms 2, 3
- The formulation of the lozenge is important, as additives like citric acid or tartaric acid may reduce efficacy by chelating zinc ions 5
Mechanism of Action
- The beneficial effects of zinc may be related to its antioxidant and anti-inflammatory properties 2
- Zinc treatment has been associated with decreased levels of proinflammatory cytokines, which may contribute to symptom improvement 2, 4
- Zinc may also have direct antiviral effects against rhinoviruses, which are common causes of colds 5
Side Effects and Considerations
- When using zinc lozenges, the benefits must be weighed against potential side effects, notably bad taste and nausea 1, 3
- Common adverse effects include unpleasant taste (reported in up to 80% of users), mouth irritation, and nausea (reported in up to 20% of users) 3, 5
- Despite these side effects, they are generally well-tolerated and self-limiting 1, 5
- Zinc nasal gel formulations have also shown efficacy in reducing cold duration (2.3 days vs 9.0 days with placebo), though these should be used with caution due to different side effect profiles 6
Alternative Formulations
- While zinc gluconate lozenges have been most extensively studied, zinc acetate lozenges may also be effective and potentially have a more favorable side effect profile 5
- Zinc nasal gel has shown promise in reducing cold duration, though it has been less extensively studied than lozenge formulations 6
Clinical Application
- Given the consistent effect of zinc on reducing the duration and severity of colds, its relatively low cost, and acceptable safety profile, zinc supplementation is a reasonable option for common cold treatment 1
- Patients should be advised to start zinc treatment immediately after symptom onset for maximum benefit 2, 3
- The decision to use zinc should consider the potential benefits of reduced symptom duration against the likelihood of experiencing taste disturbances and nausea 1, 3