Zinc supplements for preventing and treating the common cold in people
What it found
Taking zinc made little or no difference to catching a cold, but may have shortened colds by about two days.
It probably raised the chance of minor side effects when used to treat a cold.
What they found
Studies in people
Preventing colds
Taking zinc to prevent colds made little or no difference to the chance of getting one. It also did not clearly reduce the number of colds over five to 18 months.
Treating cold duration
When taken during a cold, zinc may have shortened it by about two days on average. Scientists are uncertain whether it changed overall symptom severity.
Side effects from prevention
It is uncertain whether taking zinc to prevent colds changed the risk of minor side effects. Thirty-one studies reported non-serious side effects across 2422 participants.
Side effects from treatment
Using zinc to treat a cold probably raised the chance of minor side effects. No treatment study gave clear information about serious side effects.
Other findings
Forms of zinc used
Most trials tested zinc lozenges, often as gluconate or acetate forms. Other studies used capsules, tablets, syrups, dissolved powders, or nasal sprays.
What the authors conclude
- They suggest that zinc probably does little to prevent colds but may shorten a cold that has already started, while raising the chance of minor side effects.
- They note wide differences in how zinc was given and what was measured across the studies.
- The authors say these differences and missing details should be kept in mind when judging how well zinc works for colds.
How it was done
Colds cause many missed days of work and school, yet there are no proven ways to prevent them or make them shorter. Zinc supplements are often recommended and taken for this purpose.
They gathered 34 randomised trials involving 8526 children and adults. Fifteen trials looked at preventing colds and 19 looked at treating them. Most studies were done in the USA, and many tested zinc lozenges at doses between 45 and 276 mg per day for up to 21 days.
What it can’t tell you
- We summarised it from the abstract only.
- These trials followed people over time and compared groups, so they can show whether zinc caused changes in cold length or side effects.
- However, the studies varied widely in how zinc was given and what they measured.
- This makes it hard to know exactly which form or dose works best.
Who paid
- Conflicts
- Daryl Nault: declares no conflict of interest. Taryn Machingo: declares no conflict of interest. Andrea G Shipper: declares no conflict of interest. Daniel A Antiporta: declares no conflict of interest. Candyce Hamel: declares no conflict of interest. Sahar Nourouzpour: declares no conflict of interest. Menelaos Konstantinidis: reports being a Statistical Editor for Cochrane Acute Respiratory Infections, but had no role in the editorial process of this review. Erica Phillips: declares no conflict of interest. Elizabeth Lipski: declares no conflict of interest. L Susan Wieland: reports funding for Cochrane Complementary Medicine from the US National Institutes of Health, National Center for Complementary and Alternative Medicine, R24 AT001293; paid to institution.
- Authors work at
- Maryland University of Integrative Health, USA; Oregon Health & Science University, USA; University of Maryland, USA
The paper
- Title
- Zinc for prevention and treatment of the common cold
- Type
- Systematic review
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Nault D, Machingo TA, Shipper AG, et al (2024). Zinc for prevention and treatment of the common cold. The Cochrane database of systematic reviews. doi:10.1002/14651858.CD014914.pub2Free full textPubMed 38719213DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error