Herbs for "Immune Support": Claims Checked
Do echinacea, elderberry, garlic, andrographis and other herbs "boost" the immune system? What reviews of colds and flu found, what they did not measure, and safety points.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Raw or unripe elderberries and other parts of the elder tree (leaves, stem) contain poisonous cyanide-producing substances. NCCIH says they can cause nausea, vomiting and severe diarrhea, and large amounts may cause serious illness. [1] This page does not give preparation steps. For poisoning call Poison Help at 1-800-222-1222 (US), and see Poisoning: What to Do First.
The claim as marketed
"Immune-boosting" herbs are sold for colds, flu and general resilience. The studies behind them mostly ask a narrower question: do people get fewer colds, or do symptoms pass faster? The studies we read measured colds and symptoms, not immune function. For goal-level advice see Immune Wellness and Immune Wellness Research and Evidence.What the evidence is
Traditional use is separate. Echinacea (Echinacea purpurea (L.) Moench [2]) was used by Native Americans for respiratory tract infections, tooth pain and snakebite. [3] Elderberry (Sambucus nigra L. [4]) has been used in folk medicine for colds and flu. [1] The table covers research.| Herb (part, form) | What the source found | Strength of evidence |
|---|---|---|
| Echinacea, colds | A Cochrane review of 24 double-blind trials (4,631 people) found that echinacea products have not been shown to help treat colds, though a weak benefit is possible. A post hoc pooling suggested a 10% to 20% relative risk reduction. [5] NCCIH says it may slightly reduce your chance of catching a cold, but it is unclear whether it shortens one. [3] | Mixed |
| Elderberry, colds and flu | NCCIH calls the research preliminary. [1] A 2019 meta-analysis of 180 participants reported reduced upper respiratory symptoms. [6] | Promising but limited |
| Elderberry, COVID-19 | NCCIH says there is no good evidence to support its use. [1] | No good evidence of benefit |
| Garlic, colds | Cochrane found only one eligible trial and insufficient evidence; claims rely largely on poor-quality evidence. [7] | Insufficient evidence |
| Andrographis (Andrographis paniculata (Burm.fil.) Nees [8]), respiratory infections | A review of 33 trials (7,175 people) found improved symptoms, but trial quality was overall poor. [9] | Promising but limited |
| Pelargonium sidoides extract | Cochrane: may relieve symptoms in adults with rhinosinusitis and colds, but doubt exists; evidence was low or very low quality. [10] | Promising but limited |
| Asian ginseng, flu | Very preliminary research suggests extract may reduce the risk of flu but not severity or duration. [11] | Insufficient evidence |
| Any herb that "boosts" immune function in healthy people | Proper evidence not found. We looked at NCCIH pages and PubMed reviews for these herbs; they report cold or flu symptoms, not immune function measures. | Marketing claim |
Cochrane's echinacea review also warned that products sold as echinacea differ appreciably in composition. [5] Results for one species, part or extract do not transfer to another.
Frequently asked questions
Does echinacea prevent colds?
A Cochrane review found no significant benefit in individual prevention trials, though pooling suggested a 10% to 20% reduction. [5]
Does elderberry work for the flu?
NCCIH describes preliminary research suggesting elderberry may relieve symptoms, and not enough information for other uses. [1]
Does garlic help colds?
Cochrane found insufficient evidence from a single trial. [7]
Can herbs boost my immune system?
We found no source showing that a herb boosts immune function in healthy people. Studies measure cold or flu symptoms instead.
Are immune-support herbs safe for everyone?
No. Echinacea can cause allergic reactions, and some herbs may interact with immune-suppressing medicines. [3]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
What regulators and agencies say
Safety
- Allergy. Echinacea is closely related to sunflowers, daisies and ragweed, and some people have allergic reactions that may be severe. [3] Some children in an echinacea trial developed rashes that may have been allergic. [3]
- Immune medicines and conditions. Theoretical reasons suggest echinacea might interact with immunosuppressants. [3] Asian ginseng may worsen autoimmune disorders. [11] See Herbs, Immunosuppressants and Organ Transplants.
- Pregnancy and breastfeeding. Little is known about elderberry in pregnancy or breastfeeding. [1] See pregnancy and breastfeeding.
- Honey for babies. The NHS says not to give honey to children under 12 months. [12]
- Who should ask first: children, pregnant people, anyone on transplant, cancer or autoimmune treatment. Ask a pharmacist (medicine interactions).
- Frequent or severe infections need a clinician: Immune Wellness Safety.
References
- NCCIH, Elderberry. Read 2026-10-23.
- GBIF Backbone Taxonomy, Echinacea purpurea (L.) Moench. Read 2026-10-23.
- NCCIH, Echinacea: Usefulness and Safety. Read 2026-10-23.
- GBIF Backbone Taxonomy, Sambucus nigra L.. Read 2026-10-23.
- Karsch-Volk M et al., Echinacea for preventing and treating the common cold, Cochrane Database Syst Rev 2014. Read 2026-10-23.
- Black elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: a meta-analysis of randomized, controlled clinical trials, Complement Ther Med 2019. Read 2026-10-23.
- Garlic for the common cold, Cochrane Database Syst Rev 2014. Read 2026-10-23.
- GBIF Backbone Taxonomy, Andrographis paniculata (Burm.fil.) Nees. Read 2026-10-23.
- Andrographis paniculata for symptomatic relief of acute respiratory tract infections in adults and children: a systematic review and meta-analysis, PLoS One 2017. Read 2026-10-23.
- Timmer A et al., Pelargonium sidoides extract for treating acute respiratory tract infections, Cochrane Database Syst Rev 2013. Read 2026-10-23.
- NCCIH, Asian Ginseng. Read 2026-10-23.
- NHS, Common cold. Read 2026-10-23.