Equinácea

Echinacea

1. Identity and Botanical Classification

Echinacea is a genus of flowering plants in the family Asteraceae (the daisy family). Echinacea species are perennials that are closely related to sunflowers, daisies, and ragweed. There are currently thought to be nine species in the genus Echinacea. Of these nine, only three are used as medicinal plants with wide therapeutic uses: Echinacea purpurea (L.) Moench, Echinacea pallida (Nutt.) Nutt., and Echinacea angustifolia DC. These species' full botanical designations are: Echinacea angustifolia DC, E. pallida (Nutt.), and E. purpurea (L.) Moench.

Though widely cultivated today, Echinacea species are native to areas east of the Rocky Mountains in the United States. The range of Echinacea spans the Atlantic drainage region of the United States and extends into south central Canada. Common names include purple coneflower (for E. purpurea), narrow-leaf coneflower (for E. angustifolia), pale coneflower (for E. pallida), Kansas snakeroot, and toothache root.

Although E. purpurea, E. pallida, and E. angustifolia belong to the same genus, they do not have the same phytochemical composition, and there are potential differences in their effect profiles. Distinguishing among Echinacea species using molecular methods is challenging due to extremely low levels of molecular divergence.

Commercial Forms and Preparations

Over 500 Echinacea-containing products are listed in the NIH Dietary Supplement Label Database. These products include tablets, extracts, and teas made using a variety of plant parts including roots, aerial parts, flowers, or combinations thereof of Echinacea species, and combination products that include other botanicals such as goldenseal and elderberry.

Root and aerial plant parts may be used raw or in formulations, while homeopathic remedies may include the whole plant. Echinacea is available in many forms over the counter, including as a tea, cream, lotion, and dietary supplement such as capsules or tablets. Preparations include expressed fresh-plant juice (succus), hydroalcoholic tinctures, dry powdered extracts, and topical creams or gels. There are problems concerning the botanical identity of Echinacea species used in commercial preparations, and this lack of standardization may contribute to the lack of rigorous clinical evidence supporting the diverse claims implied for these products.

2. Traditional and Historical Use

North American Indigenous Peoples

The purple coneflower, Echinacea angustifolia, was the most widely used medicinal plant of the Plains Indians. It was used for a variety of ailments, including toothache, coughs, colds, sore throats, snakebite, and as a painkiller. A total of 19 tribes have been documented using Echinacea species, with Echinacea angustifolia being the best documented, primarily because little ethnobotany was reported from eastern and southern tribes in the USA.

Archaeological evidence of indigenous use dates back to the 18th century. Traditional use included external application for insect bites, burns, and wounds; chewing of roots for throat and tooth infections; and internal use for cough, pain, snake bites, and stomach cramps. Some Plains tribes used Echinacea for cold symptoms: the Kiowa used it for coughs and sore throats, the Cheyenne for sore throats, the Pawnee for headaches, and many tribes including the Lakota used it as a pain medication.

Ethnobotanical studies made by the WHO refer, among the documented empirical uses of Echinacea, to its use against snakebites, to heal wounds, and as a primitive antibiotic. Purple coneflower (Echinacea angustifolia) and other Echinacea species have been described as the most widely utilized and important medicinal plants used by Indigenous people of the Great Plains. The plant is still being harvested and used traditionally today in many tribal communities.

Lewis and Clark learned about Echinacea during their expedition and in 1805 shipped the roots and seeds back to President Jefferson as one of their more important finds.

Entry into Western Medicine and European Use

Echinacea was one of the basic antimicrobial herbs of eclectic medicine from the mid-19th century through the early 20th century, and its use was documented for snakebite, anthrax, and for relief of pain. The first Echinacea preparation, known as Meyers Blood Purifier, arrived on the market around 1880, as an elixir for rheumatism, neuralgia, and rattlesnake bites. H. C. F. Meyer used it as a patent medicine in the 1870s and introduced it to the medical profession.

From 1887, the plant was incorporated into a variety of patent medicines, and by the 1920s Echinacea was the largest selling patent medicine in North America. Echinacea was included in the National Formulary of the United States from 1916 to 1950; however, after years of debate over its effectiveness, use declined in the 1930s. As interest in Echinacea waned in North America it increased in Europe.

In the past, Echinacea was also employed in eclectic medicine to treat septic conditions. In the mid-1800s the American Eclectic physicians began to use Echinacea and its use spread to Europe, where it gained even more popularity. By the beginning of the 20th century, it was one of the most frequently used herbal medicines in the United States.

Regulatory Recognition

In March 1989, the Commission E of the German Federal Health Agency (BGA) published a labeling standard monograph for authorized medicines containing preparations of the fresh pressed juice (liquid or dried juice) of the flowering aerial parts of E. purpurea. The German Commission E approved the aerial parts of the Echinacea purpurea plant, manufactured as a fresh-pressed juice in 22% ethanol by volume (e.g., Echinacin and Echinaguard), and the roots of the E. pallida plant, manufactured as a water-alcohol extract, for clinical use. The root of E. purpurea and the root of E. angustifolia were not approved, due to a lack of clinical trials.

In 2014, the HMPC (European Medicines Agency) issued a recommendation for pressed juice from the fresh herb of the E. purpurea plant for the short-term prophylaxis and treatment of acute upper respiratory tract infections in adolescents and adults.

Although Echinacea root (rhizome and root of E. angustifolia and/or E. pallida) was an official drug monographed in the National Formulary of the United States from the fourth edition (NF IV, 1916) until its omission from the ninth edition (NF IX, 1950), the official compendial history of E. purpurea did not begin until the late 20th century.

3. Key Constituents and Active Compounds

The biologically active constituents of Echinacea are believed to be polyacetylenes, polysaccharides, alkamides, and phenolics (e.g., caftaric acid, chlorogenic acid, caffeic acid, cynarin, echinacoside, and chicoric acid), the composition of which may vary depending on the species, the plant part used in preparations, and other environmental conditions.

Other compounds isolated from Echinacea species include resins, glycoproteins, sterols, minerals, and the alkaloids tussilagine and isotussilagine.

The principal compound classes and their characteristics include:

• Alkamides (Alkylamides): Alkamides are the major lipophilic constituents of Echinacea preparations. In earlier investigations they have been shown to possess stimulatory effects on phagocytosis. Isobutylamides, held responsible for Echinacea's local anesthetic effect, are major constituents of the roots of E. angustifolia and E. purpurea. The amides of E. purpurea root have mainly a 2,4-dienoic unit such as dodeca-2E,4E,8Z,10E-tetraenoic acid isobutylamide, whereas those of E. angustifolia root favor a monoenoic structure.
• Caffeic Acid Derivatives (Phenolics): The principal caffeic acid derivatives in E. purpurea are chicoric acid, chlorogenic acid, echinacoside, caftaric acid, and cynarin. Echinacoside is particularly concentrated in roots of E. pallida and E. angustifolia, while chicoric acid predominates in E. purpurea.
• Polysaccharides: Echinacea's anti-inflammatory properties are largely attributed to its polysaccharides.
• Glycoproteins: Phytochemical constituents include the caffeic acid derivatives (also called phenolics), alkamides, glycoproteins, and polysaccharides.
• Polyacetylenes: A number of polyacetylenes have been identified from the roots of all three commercial species. Echinolone, isolated from E. angustifolia, has shown insecticidal activity. At least 13 other polyacetylenes have been isolated.

Recent NCCIH-sponsored research suggests that the activity of Echinacea extracts is influenced by soil conditions that affect the plant's bacterial community.

4. Mechanisms of Action

Immunomodulation

Three pathways are responsible for the immunostimulant action of Echinacea species or preparations: phagocytosis activation, fibroblast stimulation, and increased respiratory activity — all of which contribute to increased leukocyte motility. Several in vivo investigations suggest that administration of the plant boosts innate immunity and bolsters the immune system's ability to fight pathogenic infections by activating neutrophils, macrophages, polymorphonuclear leukocytes (PMN), and natural killer (NK) cells.

Cannabinoid Receptor Binding of Alkamides

Recent experiments have demonstrated that alkamides are detectable in human blood in relevant concentrations after oral administration of Echinacea preparations. Alkamides show structural similarity with anandamide, an endogenous ligand of cannabinoid receptors. Consequently, it was found that alkamides bind significantly to CB2 receptors, which is now considered a possible molecular mode of action of Echinacea alkamides as immunomodulatory agents.

At low concentrations (around 50 nM), alkamides can increase the production of interleukin-6 (IL-6) in human whole blood. Conversely, they can suppress the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and interleukin-12p70 (IL-12p70) in lipopolysaccharide-stimulated immune cells. This dual action allows Echinacea to fine-tune the immune response, potentially enhancing it when needed while also preventing excessive inflammation.

The binding of alkamides to CB2 receptors also activates multiple signal transduction pathways. These include increased cAMP levels, activation of p38/MAPK and JNK signaling, and activation of transcription factors like NF-κB and ATF-2/CREB-1. These pathways collectively contribute to the overall immunomodulatory effects of Echinacea alkamides, influencing various aspects of immune cell function and proliferation.

Antiviral Mechanisms

Recent studies have revealed that preparations derived from certain species and plant parts, but not all, possess potent antiviral activities at non-cytotoxic concentrations, particularly against membrane-containing viruses. All strains of human and avian influenza viruses tested (including a Tamiflu-resistant strain), as well as herpes simplex virus, respiratory syncytial virus, and rhinoviruses, were very sensitive to a standardized Echinacea purpurea preparation. In mechanistic studies, the influenza virus-specific hemagglutinin and neuraminidase were inhibited.

Antibacterial Activity

The antibacterial activity of Echinacea against respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Legionella pneumophila) and skin pathogens (Staphylococcus aureus, Propionibacterium acnes) has been reviewed in preclinical studies. These findings are predominantly from in vitro and preclinical investigations, and their direct clinical relevance in humans remains to be established.

5. Scientific Evidence by Area of Use

5.1 Upper Respiratory Tract Infections and the Common Cold

The most extensively studied application of Echinacea is the prevention and treatment of upper respiratory tract infections (URTIs), particularly the common cold. The body of evidence is substantial but produces mixed conclusions, partly attributable to the wide heterogeneity of preparations studied.

The landmark systematic review is the Cochrane Review by Karsch-Völk et al. (2014), the most comprehensive meta-analysis available: Twenty-four double-blind trials with 4,631 participants including a total of 33 comparisons of Echinacea preparations and placebo met the inclusion criteria. A variety of different Echinacea preparations based on different species and parts of plant were used. The majority of trials investigated whether taking Echinacea preparations after the onset of cold symptoms shortens the duration compared with placebo. Although it seems possible that some Echinacea products are more effective than a placebo for treating colds, the overall evidence for clinically relevant treatment effects is weak. In general, trials investigating Echinacea for preventing colds did not show statistically significant reductions in illness occurrence; however, nearly all prevention trials pointed in the direction of small preventive effects.

Ten trials were considered to have a low risk of bias, six to have an unclear risk of bias, and eight to have a high risk of bias. Ten trials with 13 comparisons investigated prevention and 15 trials with 20 comparisons investigated treatment of colds (one trial addressed both). Due to the strong clinical heterogeneity of the studies, the reviewers refrained from pooling for the main analysis.

An earlier systematic review published in The Lancet Infectious Diseases (Linde et al., Cochrane, 2006), also found mixed results, with two trials investigating 8–12 weeks of prevention showing no clear effect: The majority of trials investigated whether taking Echinacea preparations after onset of cold symptoms shortens duration or decreases severity of symptoms, compared with a non-active placebo. Two trials investigating whether taking Echinacea preparations for 8 to 12 weeks prevented colds found no clear effect compared with placebo.

A meta-analysis conducted by researchers at the University of Connecticut School of Pharmacy provided more optimistic results: Clinical trials were included if they were randomized and placebo-controlled, evaluated Echinacea-containing products in the prevention or treatment of colds, and adequately reported data on either cold incidence or cold duration. All studies were reviewed independently by three of the authors. The authors identified 14 studies that met the criteria for inclusion. These studies reported on 1,356 subjects for the incidence of colds and 1,630 subjects for the duration of colds.

A 2019 systematic review and meta-analysis published in Complementary Therapies in Medicine found that: Evidence suggests Echinacea might have a preventative effect on the incidence of upper respiratory tract infections, but whether this effect is clinically meaningful is debatable. The reviewers did not find any evidence for an effect on the duration of upper respiratory tract infections. Based on the results of this review, users of Echinacea can be assured that Echinacea preparations are safe to consume in the short term; however, they should not be confident that commercially available remedies are likely to shorten the duration or effectively prevent URTIs.

Earlier narrative reviews of individual trials reported more favorable findings: Nine treatment trials and 4 prevention trials were found. Eight of the treatment trials reported generally positive results, and 3 of the prevention trials reported marginal benefit. Methodologic quality of the majority of the trials was modest. Evidence from published trials suggests that Echinacea may be beneficial for the early treatment of acute URIs. The influence of publication bias on those results is unknown. Echinacea preparations vary widely in composition, and are often found in combination with other potentially active constituents, making specific dose recommendations problematic.

A study in Germany in 1993 (published in English 1997) illustrated species-specific results: A randomized, placebo-controlled, double-blind trial studied 115 viral URI patients with flu-like symptoms. The treatment for 70 subjects was a liquid E. pallida root hydroalcoholic extract (dose = 900 mg root). It reduced viral infections to 9.1 days, compared to 13 days for the 45 patients given placebo (P < 0.0001). The reduction of overall symptom score for cold, weakness, extremity pain, and headache by the extract was likewise statistically significant (P < 0.0004).

A German double-blind study also showed dose-dependent effects: A 1992 placebo-controlled, double-blind study showed that a 1:5 strength tincture of E. purpurea root extracted with 55% ethanol was effective at a daily dose of 180 drops (900 mg root), but not at half this amount. It significantly reduced duration and severity of flu-like symptoms compared to placebo.

A 2023 randomized blinded controlled trial in adults with RTIs explored higher dosing: Healthy adults (n = 409) were randomized between November 2018 and January 2019 to one of four Echinacea formulations taken in case of an RTI for up to 10 days. New formulations A (lozenges) and B (spray) delivered an increased dose of 16,800 mg/day Echinacea extract during days 1–3 and 2,240–3,360 mg/day afterward; as controls, conventional formulations C (tablets) and D (drops) delivered a lower daily dose of 2,400 mg, usually taken for prevention. In a previous clinical study on the treatment of the common cold, a preparation with a seven times higher content of Echinacea (16,800 mg EF daily) performed better than placebo and than dosages that are typically administered for the long-term prevention of RTIs (2,400 mg EF extract daily).

Overall evidence strength for common cold: Weak to moderate, highly heterogeneous. The Cochrane review's finding that evidence is insufficient to recommend a specific preparation, combined with methodological variability across trials, means firm conclusions cannot be drawn. Some specific preparations — particularly those using expressed juice of E. purpurea aerial parts — appear more consistently positive in individual trials.

5.2 Prevention of Respiratory Infections

In 2014, the European Medicines Agency's HMPC issued a recommendation for pressed juice from the fresh herb of the E. purpurea plant for the short-term prophylaxis and treatment of acute upper respiratory tract infections in adolescents and adults.

Five months of Echinacea fresh plant extract (EF) prevention during the COVID-19 pandemic (2020–2021) reportedly reduced enveloped virus infections by 43.2%, coronavirus infections by 48.3%, and SARS-CoV-2 by 63.1% (p < 0.05). These figures come from a single published clinical study and require independent replication before definitive conclusions can be drawn.

5.3 Other Investigated Areas

Ongoing research continues to investigate Echinacea's pharmacological properties and potential therapeutic applications, including anti-inflammatory, analgesic, anxiolytic, and antimicrobial effects.

No rigorous scientific studies support claims that Echinacea helps prevent cancer or improves immunity, blood sugar, anxiety, and inflammation, or promotes wound healing — at least not to the degree that definitive clinical recommendations can be made from the available human trial data.

In pharmacological studies validated experimentally and published in specialized literature, there are reports of antiviral, anticancer activity, and immunomodulatory effects, but the bulk of this evidence is in vitro or animal-based and has not been confirmed in human clinical trials for most of these applications.

6. Body Systems and Health Areas

• Immune System: These species and their extracts are most often used for the prevention and treatment of upper respiratory tract infections, such as colds and flu, and as an immune stimulant.
• Respiratory System: Echinacea is a common botanical used in dietary supplements, primarily to treat upper respiratory tract infections and to support immune function.
• Antimicrobial / Antiviral: Preparations derived from certain species and plant parts possess potent antiviral activities, particularly against membrane-containing viruses, including all strains of human and avian influenza viruses tested, herpes simplex virus, respiratory syncytial virus, and rhinoviruses. These findings are principally from in vitro and preclinical studies.
• Anti-inflammatory: Bioactive constituents such as polysaccharides, alkamides, flavonoids, and phenolic acid derivatives have been shown to enhance immune function and exhibit anti-inflammatory, antioxidant, antiviral, and antibacterial properties in laboratory studies.
• Skin / Topical: Some people apply Echinacea as a cream or ointment to treat skin disorders and promote healing of wounds. Evidence from in vitro and preclinical studies confirms that pharmacologically active constituents of Echinacea purpurea, E. angustifolia, and E. pallida exert a multifaceted impact on skin health, mediated by a synergy of antioxidant, anti-inflammatory, immunomodulatory, and regenerative mechanisms.
• Anxiolytic: Alkamides' binding to CB2 receptors has led researchers to investigate potential anxiolytic effects, but robust human clinical trial data in this area remain limited.

7. Dosage Forms and Dosages Reported in Studies

Dosing varies considerably by preparation type, plant species, and intended use. Echinacea preparations vary widely in composition, and are often found in combination with other potentially active constituents, making specific dose recommendations problematic.

The following dosages have been cited in published clinical studies and regulatory documents:

• E. pallida root hydroalcoholic extract: In a 1993/1997 German trial, the dose was 900 mg root equivalent per day in liquid extract form, taken for the treatment of viral URIs.
• E. purpurea root tincture (1:5 in 55% ethanol): A daily dose of 180 drops (equivalent to 900 mg root) was effective in a 1992 German double-blind study; half this dose was not effective.
• E. angustifolia dried herb capsules: One North American trial treated 190 undergraduate students with a 250-mg capsule preparation of dried E. angustifolia three times per day.
• Echinacea fresh plant extract (EF), high-dose acute treatment: New formulations (lozenges and spray) delivered an increased dose of 16,800 mg/day extract during the first 1–3 days of an RTI and 2,240–3,360 mg/day afterward.
• Echinacea fresh plant extract (EF), conventional prevention dose: Conventional tablet and drop formulations delivered a lower daily dose of 2,400 mg, typically used for prevention.
• E. purpurea root extract (HIV drug interaction study): Echinacea purpurea root extract capsules were administered at 500 mg every 6 hours from days 1 to 14.

Approximately 70% of published studies used very different preparations that differed in terms of plant species, plant part, or preparation, which is a major source of heterogeneity in the evidence base and makes cross-study comparisons and uniform dosing recommendations unreliable.

8. Safety Considerations and Drug Interactions

General Safety Profile

It is likely safe for most adults to consume products with extracts of E. purpurea, and some mixtures of E. purpurea and E. angustifolia, for short periods of time. Echinacea is generally considered safe, with severe side effects being rare. Most users experience few adverse effects, with mild reactions such as gastrointestinal discomfort or skin irritation occurring infrequently.

Most adverse effects are mild and transitory; they include dizziness, fatigue, headache, and gastrointestinal symptoms. The number of patients dropping out or reporting adverse effects did not differ significantly between treatment and control groups in prevention and treatment trials in the Cochrane analysis.

Allergic Reactions

Some people have allergic reactions to Echinacea, which may be severe. There is a potential for allergic reactions, particularly in individuals allergic to members of the Asteraceae family, which includes ragweed, chrysanthemums, marigolds, and daisies. Rare adverse events include dermatitis and anaphylaxis.

Use in Children

It is possibly safe for children to consume E. purpurea extract for short periods of time. However, some children participating in a clinical trial of Echinacea developed rashes, which may have been caused by an allergic reaction. There is concern that allergic reactions could be severe in some children.

Populations Requiring Caution

Echinacea should be avoided in patients with autoimmune disorders, multiple sclerosis, advanced HIV infection, tuberculosis, and organ transplants because it may stimulate T cells.

Drug Interactions

There is conflicting evidence about whether Echinacea interacts with some drugs metabolized by the liver, and there are theoretical reasons to suspect that Echinacea might interact with immunosuppressants or caffeine.

Echinacea may negate the beneficial effects of immunosuppressants, which are used, for example, to prevent rejection of organ transplants. Echinacea may antagonize the effects of immunosuppressants; however, clinical relevance is not known.

Echinacea may increase blood levels of caffeine by as much as 30%.

Echinacea inhibits some cytochrome P-450 enzymes and induces some enzymes; it can therefore potentially interact with medications metabolized by these pathways. Echinacea taken for longer than 8 weeks may interact with medications that can cause liver damage, thereby increasing the risk of liver damage.

A clinical pharmacokinetic study in HIV-infected patients provides one specific data point: An open-label, fixed-sequence study in 15 HIV-infected patients receiving darunavir/ritonavir (600/100 mg twice daily) for at least 4 weeks added Echinacea purpurea root extract capsules (500 mg every 6 hours) from days 1 to 14. Co-administration with Echinacea purpurea resulted in little change in darunavir pharmacokinetic parameters, suggesting no clinically significant interaction in this specific context.

In vitro, Echinacea reduced the formation of the active drug oseltamivir and may therefore reduce efficacy, but clinical significance is as yet undetermined.

Over 400 drug interactions have been reported with Echinacea, but most are not considered serious. Echinacea can affect blood levels of certain drugs, which may lead to side effects. Current evidence indicates that the risk of drug interactions between Echinacea supplements and most medications is low, according to NCCIH.

Rare Adverse Events (Case Reports)

Case reports have documented profound thrombocytopenia in a 61-year-old man with non-small cell lung cancer who was concurrently taking Echinacea while receiving chemoradiation with cisplatin and etoposide, as well as hypereosinophilia in a 58-year-old man following Echinacea consumption, with symptoms improving after discontinuing Echinacea. These represent isolated case reports and causal relationships cannot be firmly established from such reports alone.

Long-Term Use

The safety of long-term Echinacea use has not been well established in clinical trials. Long-term use and high doses may cause overstimulation, allergic reactions, or drug interactions. Despite equivocal clinical effects, the safety data on Echinacea are relatively strong compared with many other herbal medicines, at least in the short term.

9. Standardization and Quality Control Challenges

Although alkamides, polysaccharides, glycoproteins, and phenolics have all been hypothesized as potential active ingredients of Echinacea, most of the published methods for ensuring identity and potency were developed to quantify the phenolic marker compounds, cichoric acid, echinacoside, and/or total phenolics.

The products on the market are manufactured in a variety of ways, include numerous species harvested from many sources, and use different plant parts. In addition, there are problems concerning the botanical identity of Echinacea species used in commercial preparations. This variability is a major obstacle to drawing firm clinical conclusions from the aggregate evidence.

Testing preparations that have been standardized to specific components seems like a desirable way to move forward, as noted by Cochrane reviewers. The limitations of this area of research include the clinical heterogeneity — for example many different preparations were tested, the risk of selective reporting, deviations from study protocols, and lack of contact with study authors.

References

• National Center for Complementary and Integrative Health (NCCIH), NIH — Echinacea: Usefulness and Safety
• Karsch-Völk M et al. — Echinacea for preventing and treating the common cold (Cochrane Review, 2014)
• Karsch-Völk M et al. — Echinacea for preventing and treating the common cold — PubMed (2014)
• Tozzi F et al. — Echinacea purpurea (L.) Moench: Biological and Pharmacological Properties. A Review — PMC (2022)
• Ahmadi F et al. — Phytochemistry, Mechanisms, and Preclinical Studies of Echinacea Extracts in Modulating Immune Responses — PMC (2024)
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• Signer J et al. — Echinacea—A Source of Potent Antivirals for Respiratory Virus Infections — PMC (2014)
• Molto J et al. — Herb-drug interaction between Echinacea purpurea and darunavir/ritonavir in HIV-infected patients — PMC (2011)
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• Merck Manual Professional Edition — Echinacea
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• HerbalGram — Echinacea purpurea Herb Profile (American Botanical Council)
• Aucoin M et al. — Can Echinacea be a potential candidate to target immunity, inflammation, and infection — PMC (2021)
• National Toxicology Program (NTP/NIEHS) — Summary of Data for Chemical Selection: Echinacea
• Critical analysis of Echinacea preparations marketed in Germany — PMC (2025)
• Echinacea-derived alkylamides as complementary immunomodulators — ScienceDirect (2026)