Echinacea

Echinacea species are native to North America, where Native peoples used them for a variety of ailments, including mouth sores, colds and snakebite ^{18Reference 18Huntley AL et al. · 2005Systematic reviewThe safety of herbal medicinal products derived from Echinacea species — systematic reviewView study →}. The root was also applied to wounds and taken for infections.

Echinacea was taken up by the Eclectic physicians of the nineteenth century and became one of the signature herbs of Western herbal medicine.

It has been used to heal wounds, to support the immune system and for respiratory infections ^{24Reference 24Sharifi-Rad M et al. · 2018ReviewEchinacea plants as antioxidant and antibacterial agents — reviewView study →}. In modern practice it is the herb taken at the first sign of a cold or flu, in concentrated doses for a few days.

Prevention is echinacea’s best-supported use, and the effect is moderate. A 2007 Lancet Infectious Diseases meta-analysis of 14 studies reported a 58% reduction in the odds of developing a cold (OR 0.42, 95% CI 0.25–0.71) and a cold 1.4 days shorter ^{2Reference 2Shah SA et al. · 2007Meta-analysisEvaluation of echinacea for the prevention and treatment of the common cold — meta-analysisView study →}. A 2006 meta-analysis of three experimental rhinovirus-inoculation studies found colds 55% more likely on placebo than on standardized extract (OR 1.55, 95% CI 1.02–2.36) ^{4Reference 4Schoop R et al. · 2006Meta-analysisEchinacea in the prevention of induced rhinovirus colds — meta-analysisView study →}.

A 2019 systematic review found a preventive risk ratio of 0.78 (95% CI 0.68–0.88), and judged its clinical relevance debatable ^{3Reference 3David S · 2019Meta-analysisEchinacea for the prevention and treatment of upper respiratory tract infections — systematic review and meta-analysisView study →}.

The Cochrane review (24 double-blind trials, 4,631 people) did not pool its main analysis because the trials differed so much. None of the 12 prevention comparisons reached significance on its own, though a post hoc pooling suggested a 10–20% relative risk reduction ^{1Reference 1Karsch-Völk M et al. · 2014Systematic reviewEchinacea for preventing and treating the common cold — systematic review (Cochrane)View study →}.

In children aged 4–12, an E. purpurea fresh-plant alcoholic extract (Echinaforce Junior, 400 mg three times daily) prevented 32.5% of respiratory infection episodes and cut antibiotic courses by 76% compared with vitamin C ^{7Reference 7Ogal M et al. · 2021RCTEchinacea reduces antibiotic usage in children through respiratory tract infection prevention — randomized controlled trialView study →}. A 2025 meta-analysis of 9 pediatric RCTs (3,169 children) found lower URTI incidence (RR 0.81) and much lower antibiotic use (RR 0.18) ^{8Reference 8Pham TP et al. · 2025Meta-analysisEfficacy and safety of Echinacea purpurea in treating upper respiratory infections and otitis media in children — systematic review and meta-analysisView study →}.

Individual trials remain inconsistent. In an experimental rhinovirus trial (Sperber 2004, n=48), E. purpurea did not reduce infection, and colds developed in 58% on echinacea against 82% on placebo, a difference that was not significant ^{9Reference 9Sperber SJ et al. · 2004RCTEchinacea purpurea for prevention of experimental rhinovirus colds — randomized controlled trialView study →}. In a prevention trial in hospital staff (O’Neil 2008, 58 analysed, 8 weeks), E. purpurea capsules did not significantly change the frequency of respiratory symptoms ^{10Reference 10O’Neil J et al. · 2008RCTEffects of echinacea on the frequency of upper respiratory tract symptoms — randomized, double-blind, placebo-controlled trialView study →}.

The trials used many different preparations, based on different species and plant parts ^{1Reference 1Karsch-Völk M et al. · 2014Systematic reviewEchinacea for preventing and treating the common cold — systematic review (Cochrane)View study →}.

Gap: the preventive effect is small, inconsistent across products, and of debatable clinical relevance; no single preparation has been confirmed across independent groups at low risk of bias.

Immune activation is echinacea’s proposed mechanism for the respiratory-infection findings, and it is well demonstrated in cells and animals. In macrophages, an ethanolic extract and isolated cichoric acid lowered LPS-stimulated NF-κB and TNF-α, and only the alkylamide fraction lowered nitric oxide ^{16Reference 16Stevenson LM et al. · 2005In vitroModulation of macrophage immune responses by Echinacea — in vitroView study →}. The same study noted that cichoric acid is unlikely to act in the body, because it has not been shown to be absorbed from the gut ^{16Reference 16Stevenson LM et al. · 2005In vitroModulation of macrophage immune responses by Echinacea — in vitroView study →}.

Polysaccharide-enriched E. purpurea extracts had the opposite effect on resting mouse macrophages, raising IL-6, TNF, IL-12 and nitric oxide through MAPK and NF-κB signaling. Given by mouth, the extract lowered the bacterial load in mice infected with Listeria ^{17Reference 17Sullivan AM et al. · 2008In vitroEchinacea-induced macrophage activation — in vitro and in vivo (mouse)View study →}.

A 2024 review catalogues enhanced macrophage and natural-killer-cell activity, phagocytosis and cytokine production across the alkylamide, caffeic-acid-derivative and polysaccharide fractions ^{22Reference 22Ahmadi F et al. · 2024ReviewPhytochemistry, mechanisms, and preclinical studies of Echinacea extracts in modulating immune responses to bacterial and viral infections — reviewView study →}.

Echinacea extracts damped signaling in activated cells and stimulated it in resting ones, so their effect is better described as immunomodulatory than as simple immune stimulation ^{16,17,22Reference 16Stevenson LM et al. · 2005In vitroModulation of macrophage immune responses by Echinacea — in vitroView study →Reference 17Sullivan AM et al. · 2008In vitroEchinacea-induced macrophage activation — in vitro and in vivo (mouse)View study →Reference 22Ahmadi F et al. · 2024ReviewPhytochemistry, mechanisms, and preclinical studies of Echinacea extracts in modulating immune responses to bacterial and viral infections — reviewView study →}.

These are cell-culture and rodent endpoints. No human trial links a measured immune change to a clinical infection outcome, and effects differ by fraction and preparation.

The root alkylamides resemble anandamide, one of the body’s own cannabinoids, and they bind to the cannabinoid CB2 receptor ^{26Reference 26Woelkart K · 2007ReviewThe role of alkamides as an active principle of Echinacea — reviewView study →}. This gives echinacea a defined molecular anti-inflammatory pathway, distinct from its immune-stimulant reputation.

In a 2017 study combining cell work with randomized clinical trials, an alkylamide-rich E. purpurea extract cut poly(I:C)-induced IL-6 and IL-8 in keratinocytes. As a topical cream, it significantly reduced atopic-eczema severity (SCORAD) against a comparator cream and raised epidermal ceramide and lipid-barrier content ^{14Reference 14Oláh A et al. · 2017RCTEchinacea purpurea-derived alkylamides exhibit potent anti-inflammatory effects and alleviate clinical symptoms of atopic eczema — randomized clinical trialsView study →}.

Caffeic-acid derivatives contribute a separate NF-κB-suppressing action in macrophages ^{16Reference 16Stevenson LM et al. · 2005In vitroModulation of macrophage immune responses by Echinacea — in vitroView study →}.

Gap: the strong human evidence is topical and dermatological; systemic anti-inflammatory benefit from oral echinacea has not been demonstrated in a clinical endpoint.

Treatment — taking echinacea once symptoms start — draws on the same large trial base as prevention, but the results are largely null. In the Cochrane review, only one of seven treatment trials reporting cold duration beat placebo, and echinacea was not shown to help treat colds ^{1Reference 1Karsch-Völk M et al. · 2014Systematic reviewEchinacea for preventing and treating the common cold — systematic review (Cochrane)View study →}.

The largest single treatment trial (Barrett 2010) enrolled 719 people aged 12–80. Tablets equivalent to 10.2 g of dried echinacea root on the first day and 5.1 g on each of the next four produced a non-significant 0.53-day shorter illness and a 28-point trend in severity. The authors concluded that the results did not support a substantive effect on the course of a cold ^{5Reference 5Barrett B et al. · 2010RCTEchinacea for treating the common cold — randomized controlled trialView study →}.

In 407 children aged 2–11 (Taylor 2003, JAMA), E. purpurea did not reduce the duration or severity of 707 respiratory infections, and rash was more common (7.1% vs 2.7% of infections, P=0.008) ^{6Reference 6Taylor JA et al. · 2003RCTEfficacy and safety of echinacea in treating upper respiratory tract infections in children — randomized controlled trialView study →}.

The 2019 meta-analysis likewise found no effect on duration (mean difference −0.45 days, CI crossing zero) ^{3Reference 3David S · 2019Meta-analysisEchinacea for the prevention and treatment of upper respiratory tract infections — systematic review and meta-analysisView study →}. A 2025 pediatric meta-analysis did find a small duration benefit (SMD −0.19), alongside a modest rise in mild adverse events ^{8Reference 8Pham TP et al. · 2025Meta-analysisEfficacy and safety of Echinacea purpurea in treating upper respiratory infections and otitis media in children — systematic review and meta-analysisView study →}.

Gap: the best-powered treatment trials are null, and any duration benefit is a fraction of a day and depends on the preparation.

Echinacea’s caffeic-acid derivatives — cichoric acid, echinacoside, caftaric acid and chlorogenic acid — are radical scavengers in vitro. A purified E. purpurea polysaccharide reduced oxidative stress and protected liver tissue in a rodent CCl₄ model, acting through the Nrf2 pathway ^{23Reference 23Hou R et al. · 2020In vitroPolysaccharide from Echinacea purpurea reduces oxidant stress in vitro and in vivo — in vitro and rodent studyView study →}.

Reviews group echinacea among antioxidant and antibacterial botanicals on the strength of this phenolic content ^{24Reference 24Sharifi-Rad M et al. · 2018ReviewEchinacea plants as antioxidant and antibacterial agents — reviewView study →}.

The activity is shared with many caffeic-acid-rich plants, and it has not been tied to any clinical antioxidant outcome in people. It is constituent- and rodent-level only, and marker content varies widely by species and plant part.

A standardized E. angustifolia root extract (40 mg twice daily for 7 days) lowered State-Trait Anxiety Inventory state-anxiety scores by about 11 points, against about 3 on placebo (P<0.01), and the effect lasted through a 3-week washout ^{11Reference 11Haller J et al. · 2020RCTDouble-blind placebo-controlled trial of the anxiolytic effects of a standardized Echinacea extractView study →}.

A 6-week trial of the EP107 extract in 108 adults (20 or 40 mg twice daily) found anxiety reductions that did not separate from placebo on the primary outcome, though secondary mood and wellbeing measures improved ^{12Reference 12Lopresti AL · 2021RCTAnxiety-relieving and mood-enhancing effects of Echinacea angustifolia (EP107) — randomised, double-blind, placebo-controlled studyView study →}.

In rodents, three of five echinacea preparations reduced anxiety-like behaviour in the elevated plus-maze and social-interaction tests. One did so across a wide dose range (3–8 mg/kg) without suppressing movement, whereas chlordiazepoxide suppressed movement at higher doses ^{13Reference 13Haller J et al. · 2010The effect of Echinacea preparations in three laboratory tests of anxiety: comparison with chlordiazepoxide — animal studyView study →}.

Both human trials used a standardized E. angustifolia root extract, and the larger one was null on its primary outcome ^{11,12Reference 11Haller J et al. · 2020RCTDouble-blind placebo-controlled trial of the anxiolytic effects of a standardized Echinacea extractView study →Reference 12Lopresti AL · 2021RCTAnxiety-relieving and mood-enhancing effects of Echinacea angustifolia (EP107) — randomised, double-blind, placebo-controlled studyView study →}.

Separate from immune modulation, echinacea extracts show direct virucidal activity against enveloped viruses. The E. purpurea preparation Echinaforce irreversibly inactivated human coronavirus 229E on contact (IC50 3.2 μg/mL), inactivated MERS-CoV and SARS-CoV-1 at similar concentrations and SARS-CoV-2 at 50 μg/mL, and protected cultured respiratory tissue exposed to 229E droplets. Pre-treating cells did not prevent infection ^{15Reference 15Signer J et al. · 2020In vitroIn vitro virucidal activity of Echinaforce against coronaviruses, including 229E and SARS-CoV-2 — in vitroView study →}.

Reviews also describe activity against herpes simplex, influenza and rhinovirus ^{22Reference 22Ahmadi F et al. · 2024ReviewPhytochemistry, mechanisms, and preclinical studies of Echinacea extracts in modulating immune responses to bacterial and viral infections — reviewView study →}. In the pediatric prevention trial, children on echinacea had fewer influenza and enveloped-virus detections than those on vitamin C ^{7Reference 7Ogal M et al. · 2021RCTEchinacea reduces antibiotic usage in children through respiratory tract infection prevention — randomized controlled trialView study →}.

No placebo-controlled human trial has shown that echinacea prevents or shortens a laboratory-confirmed viral infection through a direct antiviral mechanism, as opposed to a symptomatic or immune one. Virucidal concentrations in a dish do not establish antiviral effects at the levels reached in tissue.

Echinacea extracts show modest in vitro activity against respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Legionella pneumophila) and skin pathogens (Staphylococcus aureus, Propionibacterium acnes) ^{22Reference 22Ahmadi F et al. · 2024ReviewPhytochemistry, mechanisms, and preclinical studies of Echinacea extracts in modulating immune responses to bacterial and viral infections — reviewView study →}, and appear in antioxidant and antibacterial screening reviews ^{24Reference 24Sharifi-Rad M et al. · 2018ReviewEchinacea plants as antioxidant and antibacterial agents — reviewView study →}.

The clinical findings in respiratory infection, including reduced antibiotic use in children ^{7,8Reference 7Ogal M et al. · 2021RCTEchinacea reduces antibiotic usage in children through respiratory tract infection prevention — randomized controlled trialView study →Reference 8Pham TP et al. · 2025Meta-analysisEfficacy and safety of Echinacea purpurea in treating upper respiratory infections and otitis media in children — systematic review and meta-analysisView study →}, are attributed to immune modulation and fewer secondary complications rather than to a direct antibiotic effect. In vitro potency is modest and depends on the preparation, and there is no evidence of a clinically meaningful antibacterial effect in the body.

Tolerability. Short-term use of echinacea has a relatively good safety record. Adverse events are not commonly reported, and stomach upset and rash are the most frequent ^{18Reference 18Huntley AL et al. · 2005Systematic reviewThe safety of herbal medicinal products derived from Echinacea species — systematic reviewView study →}. A 2019 meta-analysis found no clear excess of adverse events over placebo in the short term ^{3Reference 3David S · 2019Meta-analysisEchinacea for the prevention and treatment of upper respiratory tract infections — systematic review and meta-analysisView study →}.

Allergy. Echinacea belongs to the daisy family (Asteraceae). It can occasionally cause allergic reactions, which may be severe, and people with allergies or asthma should consider its use carefully ^{18Reference 18Huntley AL et al. · 2005Systematic reviewThe safety of herbal medicinal products derived from Echinacea species — systematic reviewView study →}.

Children. In one pediatric cold trial, rash occurred in 7.1% of infections treated with echinacea against 2.7% with placebo ^{6Reference 6Taylor JA et al. · 2003RCTEfficacy and safety of echinacea in treating upper respiratory tract infections in children — randomized controlled trialView study →}. A 2025 pediatric meta-analysis found a modest increase in mild adverse events ^{8Reference 8Pham TP et al. · 2025Meta-analysisEfficacy and safety of Echinacea purpurea in treating upper respiratory infections and otitis media in children — systematic review and meta-analysisView study →}.

Autoimmune disease. Because echinacea stimulates innate immunity, caution is traditionally advised in progressive systemic and autoimmune disease. Reviews list its use in autoimmune disease among its open safety questions ^{27Reference 27Barnes J et al. · 2005ReviewEchinacea species: a review of their chemistry, pharmacology and clinical properties — reviewView study →}.

Drug interactions. In 13 healthy volunteers, four weeks of E. purpurea lowered blood levels of midazolam, a CYP3A test drug, by about a quarter, but did not change fexofenadine or the HIV drugs lopinavir and ritonavir ^{31Reference 31Penzak SR et al. · 2010Echinacea purpurea significantly induces cytochrome P450 3A activity but does not alter lopinavir-ritonavir exposure in healthy subjects — clinical pharmacokinetic studyView study →}. In 12 healthy volunteers, eight days of E. purpurea root raised the systemic clearance of midazolam by about a third and slowed the clearance of caffeine, a CYP1A2 effect; tolbutamide and dextromethorphan were barely affected ^{32Reference 32Gorski JC et al. · 2004AnimalThe effect of echinacea (Echinacea purpurea root) on cytochrome P450 activity in vivo — clinical pharmacokinetic studyView study →}.

A 2019 meta-analysis likewise found that E. purpurea significantly increased the clearance of midazolam ^{21Reference 21Awortwe C et al. · 2019Meta-analysisInteraction of herbal products with prescribed medications — systematic review and meta-analysisView study →}. An earlier 28-day study, which measured enzyme activity from single blood and urine samples, found no significant effect on CYP1A2, CYP2D6, CYP2E1 or CYP3A4 ^{19Reference 19Gurley BJ et al. · 2004RCTIn vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, saw palmetto — randomized crossover trialView study →}.

Echinacea increased the clearance of S-warfarin without changing its effect on clotting (INR) in 12 healthy men ^{20Reference 20Abdul MIM et al. · 2010RCTPharmacokinetic and pharmacodynamic interactions of echinacea and policosanol with warfarin in healthy subjects — randomized crossover trialView study →}.

Long-term use. The safety record covers short-term use ^{18Reference 18Huntley AL et al. · 2005Systematic reviewThe safety of herbal medicinal products derived from Echinacea species — systematic reviewView study →}. Traditionally echinacea is taken in short courses rather than continuously.