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Zinc for prevention and treatment of the common cold.

2024 Cochrane update (34 RCTs, n=8,526): zinc versus placebo showed low-certainty evidence of little or no prevention benefit on cold incidence (RR 0.93) but suggested lower mean cold duration when used for treatment (MD −2.37 days, low certainty, high heterogeneity), with moderate-certainty increase in non-serious adverse events during treatment.

Design

  • Cochrane systematic review; 34 RCTs (n = 8,526); 15 prevention, 19 treatment
  • Inclusion: zinc-only vs placebo; excluded zinc bundled with other vitamins/minerals/herbs

Prevention (abstract-reported)

  • Pooled RR 0.93 (95% CI 0.85–1.01; I² = 20%; 9 studies, 1449 participants; low-certainty)

Treatment (abstract-reported)

  • Mean cold duration MD −2.37 days (95% CI −4.21 to −0.53; I² = 97%; 8 studies, 972 participants; low-certainty)
  • Non-serious adverse events: RR 1.34 (95% CI 1.15–1.55; moderate-certainty; 16 treatment studies)

Evidence hygiene

  • Many trials at unclear/high risk of bias in ≥1 domain; formulation (lozenge salts, syrups, intranasal) and dose vary—read full review before equating products.

Publication

Nault D, Wieland LS, et al. Cochrane Database Syst Rev. 2024 May 9;5(5):CD014914. PMID 38719213.

Outcomes

  • All-Cause Mortality Risk
    Events: /
  • Treatment: mean cold duration MD −2.37 days (95% CI −4.21 to −0.53; I²=97%; low-certainty) across 8 RCTs vs placebo.
  • All-Cause Mortality Risk
    Events: /
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