Supplements for colds & immune support

Catching fewer colds or recovering faster.

Start with the basics

Sleep, handwashing, and vaccinations are the best-proven ways to reduce infections.

Talk to a healthcare professional first

This information is for education only and is not medical advice, diagnosis, or treatment. Supplements can interact with medications and health conditions. Check with your doctor or pharmacist before starting anything, especially if you take medication, are pregnant or breastfeeding, or have a health condition. These statements have not been evaluated by the FDA; supplements are not intended to diagnose, treat, cure, or prevent any disease.

Ranked by strength of evidence

Vitamin D

CLimited evidence

An earlier meta-analysis suggested vitamin D slightly reduced respiratory infections, but the 2025 update (61,000+ participants) found the effect was no longer statistically significant, with no clear benefit by baseline vitamin D level or dosing schedule.

Dose used in studies: 400–2,000 IU/day (daily dosing)
Time to effect: Weeks to months
Most relevant for: Correcting a confirmed deficiency is worthwhile for overall health

Studies (2)

Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data — BMJ, 2017 · Meta-analysis · PMID 28202713
Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data — Lancet Diabetes Endocrinol, 2025 · Meta-analysis · PMID 39993397

Safety, side effects & interactions →Where to buy (affiliate)

Zinc

CLimited evidence

Zinc lozenges started within 24 hours of symptoms may shorten colds by about a day in some trials; a 2024 Cochrane review rated the overall evidence as low certainty.

Dose used in studies: Lozenges providing ~75–100 mg/day zinc, for a few days only
Time to effect: Within days of starting

Studies (2)

Zinc for prevention and treatment of the common cold — Cochrane Database Syst Rev, 2024 · Systematic review · PMID 38719213
Zinc acetate lozenges for treating the common cold: an individual patient data meta-analysis — Br J Clin Pharmacol, 2016 · Meta-analysis · PMID 27378206

Safety, side effects & interactions →Where to buy (affiliate)

Echinacea

CLimited evidence

An older meta-analysis suggested echinacea reduced the odds of catching a cold, but trials vary greatly in product and quality, and later reviews found weak or no benefit.

Dose used in studies: Varies by product
Time to effect: Days

Studies (1)

Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis — Lancet Infect Dis, 2007 · Meta-analysis · PMID 17597571

Safety, side effects & interactions →Where to buy (affiliate)

Vitamin C

CLimited evidence

A Cochrane review found regular vitamin C did not reduce how often most people catch colds but slightly shortened their duration (about 8% in adults). It roughly halved cold risk in people under heavy physical stress (e.g. marathon runners).

Dose used in studies: 200–1,000 mg/day taken regularly
Time to effect: Needs regular use before colds start
Most relevant for: People under heavy physical stress

Studies (1)

Vitamin C for preventing and treating the common cold — Cochrane Database Syst Rev, 2013 · Meta-analysis · PMID 23440782

Safety, side effects & interactions →Where to buy (affiliate)

When to see a doctor

You have a high fever, trouble breathing, or symptoms lasting more than 10 days.