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Moderate evidenceImmunity

Zinc

An essential mineral for immune function. Zinc lozenges started at the very beginning of a cold may shorten its duration.

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What the science says

  • Shorter cold duration Moderate evidence

    Meta-analyses of trials with zinc acetate lozenges (high doses, started within 24h of symptoms) showed the common cold shortened by about 2–3 days. The form and timing of use matter a lot.

  • Immune support in deficiency Strong evidence

    Zinc deficiency clearly impairs immunity; correcting it restores immune function. Deficiency is more common in older adults, strict vegetarians, and people with intestinal disorders.

Dosage & safety

Studied doseMaintenance: 8–11 mg/day (daily requirement). For colds, studies used lozenges totaling 75+ mg/day in divided doses, for a few days.
SafetyProlonged use of high doses (>40 mg/day) can cause copper deficiency. Lozenges may cause nausea and altered taste.

How to take it

TimingFor a cold, a lozenge every 2-3 hours starting within 24 hours of symptoms; for maintenance, timing does not matter.
With food?With food for daily tablets — zinc on an empty stomach very commonly causes nausea. Lozenges are dissolved in the mouth, not swallowed with a meal.
Worth knowingCheck the elemental zinc figure: 220 mg of zinc sulfate is only about 50 mg of zinc, and labels are inconsistent about which number they print.

Interactions

With medications

  • tetracycline and fluoroquinolone antibiotics

    Zinc binds the antibiotic in the gut and cuts its absorption. take the antibiotic at least 2 hours before or 4-6 hours after zinc

  • penicillamine

    Zinc and penicillamine bind each other, reducing the effect of both. separate doses by at least 2 hours

With other supplements

  • copper

    Zinc above 40 mg/day taken for months induces copper deficiency, which can cause anaemia and neuropathy. keep long-term zinc under 40 mg/day, or add 1-2 mg copper if higher doses are necessary

  • iron

    Iron and zinc compete for the same absorption pathway when taken together in supplemental doses. separate by at least 2 hours

  • calcium

    High-dose calcium modestly reduces zinc absorption. take at different times of day if you use both

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Do zinc lozenges work for colds?

The evidence is moderate: trials of zinc acetate lozenges started within 24 hours of symptoms shortened colds by about 2–3 days. The zinc form and timing matter a lot, and the studies used 75+ mg/day for just a few days.

How much zinc per day?

For maintenance, 8–11 mg/day of zinc meets the requirement. Check the elemental zinc figure on the label, since 220 mg of zinc sulfate provides only about 50 mg of zinc.

Can taking too much zinc be harmful?

Yes. Taking more than 40 mg/day of zinc for months can cause copper deficiency, which can lead to anaemia and neuropathy.

Should I take zinc with food?

Take daily zinc tablets with food, because zinc on an empty stomach very commonly causes nausea. Zinc lozenges are dissolved in the mouth instead and can also cause nausea and altered taste.

Scientific references

Where to buy

NOW Foods, Zinc, 50 mg, 250 Tablets

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