Awaiting clinical review. This page is built from sourced entries but has not yet been signed off by a pharmacist or clinician.
Natural remedies for immunity
Direct answer
No supplement here has been shown to prevent infections or boost a healthy immune system. Echinacea and elderberry are both rated Limited (2) for preventing colds, and quercetin is only Traditional (1) for immune protection in athletes. The caution that matters most is echinacea's risk of allergic reaction, which can be severe in people with daisy-family allergies, hay fever, asthma or eczema.
Compare the options
Click a column heading to sort.
| Rated for | Typical form & use | Main caution | |||
|---|---|---|---|---|---|
| Echinacea Echinacea purpurea/angustifolia | Limited | Preventing colds | E. purpurea juice, 6–9 ml a day | Allergy risk, esp. with daisy-family allergy | About a week |
| Elderberry Sambucus nigra (ripe fruit, cooked) | Limited | Preventing colds | Capsule extract, 300 mg 2–3 times a day | Raw or unripe berries, leaves and stems are toxic | 2–3 days |
| Quercetin Plant flavonoid (isolated compound) | Traditional | Immune protection in athletes | Capsule, about 1,000 mg daily | Can change how some medicines are absorbed | 4+ weeks |
- Rated for
- Preventing colds
- Form
- E. purpurea juice, 6–9 ml a day
- Onset
- About a week
- Rated for
- Preventing colds
- Form
- Capsule extract, 300 mg 2–3 times a day
- Onset
- 2–3 days
- Rated for
- Immune protection in athletes
- Form
- Capsule, about 1,000 mg daily
- Onset
- 4+ weeks
Quick picks
Rated Limited (2) for preventing colds: the 2014 Cochrane review found no significant effect in any of its 12 prevention comparisons, though pooling them after the fact hinted at a 10% to 20% fewer colds. Two later meta-analyses report bigger effects for recurrent infections, but some authors of the 2024 one declare payments from an echinacea maker.
Gentlest optionElderberryRated Limited (2) for preventing colds: in the one air-travel trial 12 of 154 people on elderberry and 17 of 158 on placebo caught a cold (relative risk 0.69, 95% CI 0.34 to 1.39), which could easily be chance. Cooked or standardised products are the only ones to consider, as raw berries, leaves and stems are toxic.
Talk to a doctor first if…
Who should avoid
Avoid echinacea if you are allergic to daisy-family plants, and ask first if you have hay fever, asthma or eczema; the EU regulator does not recommend it for autoimmune disease, weakened immunity or children under 12. Never eat raw or unripe elderberries, leaves or stems. Quercetin is best avoided in kidney disease and hormone-sensitive cancer (animal data), and in pregnancy, where there are no safety data.
Known interactions
Echinacea and immunosuppressants (severity 2): NCCIH and the EU regulator advise against combining them for theoretical reasons, though no clinical harm is documented in the sources we read. Quercetin is reported to change how some medicines are absorbed, without the drugs being named, so ask a pharmacist if you take regular medication. No source we opened names an interaction for elderberry.
Before you reach for an ingredient
Better-tested measures than any supplement here are washing your hands and getting enough sleep. Both are about lowering the chance of catching an infection, which is what most "immune boosting" claims are really after.
- Hand hygiene modestly lowers the risk of respiratory illness: a Cochrane review of 19 trials found about 11% fewer respiratory illnesses (low-certainty evidence), and 14% fewer acute respiratory infections in nine trials (moderate certainty). It made little or no clear difference to laboratory-confirmed influenza.5
- Short sleep was linked to catching colds: in 164 healthy adults exposed to a cold virus, those who slept under 5 hours or 5 to 6 hours a night were around four times as likely to develop a cold as those sleeping more than 7 hours. It is a single study with a modest sample, so treat it as a reason to protect your sleep rather than a guarantee.6
- The NHS advice for avoiding colds is washing hands with warm water and soap, not sharing towels or cups with someone who has one, not touching your eyes or nose, and staying fit and healthy. It says there is little evidence that vitamin C, echinacea or garlic prevent colds.7
Questions people ask
Can any supplement boost your immune system?
Not in a way the evidence supports. For the options on this page, the best result is a small, uncertain reduction in colds from echinacea, and the Cochrane review could not confirm it. A healthy immune system is not something the trials here show can be made stronger with a supplement.
Does echinacea prevent colds?
Not reliably. The 2014 Cochrane review found no statistically significant effect in any prevention comparison, and the authors called the hint of a 10% to 20% reduction of questionable clinical relevance. Results depend on the species, plant part and preparation, so one product's trial does not vouch for another.
Does elderberry stop you catching colds or flu?
There is no good evidence that it does. The systematic review concluded elderberry may not reduce the risk of developing a cold, and the small trials that suggest it shortens illness were mostly funded by the makers of the product tested. It is not shown to prevent illness.
Is quercetin good for immunity?
We found no systematic review showing quercetin prevents infections. A review of flavonoids and exercise found only two studies with immune benefits, and both used anthocyanin supplements, not quercetin.
Sources
- Cochrane review Karsch-Völk M, Barrett B, Kiefer D, Bauer R, Ardjomand-Woelkart K, Linde K. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. 2014.
- Regulator/health agency NCCIH. Echinacea: Usefulness and Safety. National Center for Complementary and Integrative Health.
- Systematic review Wieland LS, Piechotta V, Feinberg T, et al. Elderberry for prevention and treatment of viral respiratory illnesses: a systematic review. BMC Complement Med Ther. 2021.
- Systematic review Ruiz-Iglesias P, Gorgori-González A, Massot-Cladera M, Castell M, Pérez-Cano FJ. Does Flavonoid Consumption Improve Exercise Performance? Is It Related to Changes in the Immune System and Inflammatory Biomarkers? A Systematic Review of Clinical Studies since 2005. Nutrients. 2021.
- Cochrane review Jefferson T, Dooley L, Ferroni E, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database Syst Rev. 2023.
- Experimental study Prather AA, Janicki-Deverts D, Hall MH, Cohen S. Behaviorally Assessed Sleep and Susceptibility to the Common Cold. Sleep. 2015.
- Health service guidance NHS. Common cold. National Health Service (page last reviewed 22 March 2024).
Draft, awaiting clinical review