Zinc

Do zinc lozenges help with colds?

Updated 10 Nov 2026

Short answer

They may shorten a cold, but zinc may make little or no difference to the risk of catching one.[1] In a 2024 Cochrane review, colds treated with zinc lasted about 2.4 days less, but the certainty of this result was low.[1] A 2012 review found the effect in adults, not in children.[2]

What the reviews found

A 2024 Cochrane review pooled 34 trials with 8,526 people. Of these, 15 tested zinc to prevent colds and 19 tested it to treat colds.[1] Half of the trials (17 of 34) gave zinc as lozenges, and zinc gluconate lozenges were the most common of these.[1]

  • Treatment: in 8 trials with 972 people, colds lasted on average 2.37 days less with zinc. The certainty was low, and the results differed a lot between trials.[1]
  • Prevention: in 9 trials with 1,449 people, zinc made little or no difference to the risk of getting a cold (risk ratio 0.93).[1]
  • Severity: it is uncertain whether zinc makes the symptoms milder.[1]

A 2012 review of 17 trials with 2,121 people found that zinc shortened colds by 2.63 days in adults. In children it found no clear effect.[2]

Dose and timing in the trials

In the Cochrane review, zinc gluconate lozenges gave 45 to 276 mg of zinc a day for 4.5 to 21 days.[1] An earlier review found that lozenges with more than 75 mg of zinc a day shortened colds, and lower doses did not.[3]

In one trial, 50 adults started zinc acetate lozenges with 13.3 mg of zinc within 24 hours of the first symptoms. They took one lozenge every 2 to 3 waking hours for as long as the symptoms lasted. Their colds were 3 days shorter than with placebo.[3]

Why it may work

Researchers think that zinc may stop rhinoviruses (cold viruses) from binding to the lining of the nose and multiplying there. Zinc may also lower inflammation.[3] Trials use lozenges or syrups because they stay in the mouth and throat for a while and bring zinc into contact with the virus there.[3]

Side effects

People who took zinc to treat a cold had more mild side effects than people on placebo (risk ratio 1.34).[1] The 2012 review found more bad taste and nausea with zinc than with placebo.[2]

The doses in many lozenge trials are above the US upper limit for adults of 40 mg a day. Doses of 50 mg or more taken for weeks can lower copper absorption.[3] Zinc and quinolone or tetracycline antibiotics can block each other's absorption, so ask a pharmacist first if you take one.[3]

What is still unknown

The trials used different forms, doses and schedules, and many reported their methods incompletely.[1] A 2021 review of 28 trials in adults also found it unclear which zinc forms and doses work best.[4]

Sources (4)

  1. Zinc for prevention and treatment of the common cold. Nault D, Machingo TA, Shipper AG, Antiporta DA, Hamel C, Nourouzpour S, et al. Cochrane Database Syst Rev, 2024. PMID 38719213
  2. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. Science M, Johnstone J, Roth DE, Guyatt G, Loeb M CMAJ, 2012. PMID 22566526
  3. Zinc: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  4. Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trials. Hunter J, Arentz S, Goldenberg J, Yang G, Beardsley J, Myers SP, et al. BMJ Open, 2021. PMID 34728441

More about zinc

What is zinc?Which foods contain zinc?What is zinc used for?What are the signs of zinc deficiency?Is zinc safe?Does zinc help children with diarrhea?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.