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Immune & early warning

Zinc lozenges

Acetate or gluconate

ModerateReal effect, but below wearable noise
1
sources
34
trials
8,526
participants (largest study)
1
study designs
The verdict

When your wearable flags an illness onset — temperature up, resting heart rate up — zinc lozenges started within 24 hours may shorten the cold by about two days (Cochrane 2024, low certainty). They do little for prevention and nothing for severity.

Why this grade
Emerging
Preliminary or mechanistic
Moderate
Some RCTs, limited replication
Strong
Multiple RCTs or meta-analyses, consistent direction

Moderate: Cochrane pooled estimate of −2.4 days but wide interval and low certainty; heterogeneous lozenge formulations.

How it works

Ionic zinc in the throat inhibits rhinovirus replication and binding.

Who it helps, and who it doesn't

Start at first symptoms/deviation; acetate or gluconate lozenges, ≥75 mg/day total. Never intranasal. Stop when well.

Measured effects (absolute, from the trials)

Every estimate, against a line of no effect

Diamonds are point estimates; the hairline is the 95% confidence interval where the trial reported one.

  • Cold duration
    days · Cochrane 2024
    −2.37
    −4.21 … −0.53
−4−20NO EFFECT

Units are never mixed on one line: each scale gets its own axis. Where a trial reported no confidence interval we leave it blank rather than inventing one.

Studies over time

1 studies across 1 years

2024 — 2024
20242025
Meta-analysis or systematic reviewRandomized or crossover trialObservational or preliminaryHover a marker for detail
Dose
≥75 mg/day total while symptomatic
Timing
Start at first deviation; stop when resolved
Safety flags
  • · Metallic taste, nausea. Never intranasal zinc (anosmia). Long-term high dose depletes copper.
Where to buyRecord what I'm taking

References

  1. 1.
    Zinc for prevention and treatment of the common cold
    Cochrane Database of Systematic Reviews · 2024 · systematic review · 34 trials · n = 8,526

    May shorten colds by ~2 days (MD −2.37, 95% CI −4.21 to −0.53); low-certainty evidence; little effect on prevention or severity.

Umbral is a wellness product, not a medical device. It does not diagnose, treat, cure or prevent any disease. Supplement information is educational; talk to a clinician before starting anything, especially if you are pregnant, under 18, managing a condition or taking medication.