- Coneflower; purple coneflower
- Black Sampson; Sampson root
For Patients & Caregivers
How It Works
Echinacea does not appear to prevent the common cold, but it may shorten the duration of colds or be of benefit in the early treatment of influenza when taken within 24–48 hours of the first symptoms.
Echinacea extract appears to stimulate immune cells in laboratory and animal studies. Some compounds found in echinacea appear to reduce inflammation, relieve pain, and kill bacteria and viruses directly. Human studies have found that echinacea is not effective for preventing the common cold or to treat respiratory infections, but it may shorten the duration of colds. One large clinical trial suggested a specific echinacea formulation was as effective as a prescription drug to treat influenza, with fewer side effects.
Few studies have been conducted on echinacea with respect to cancer or cancer treatment. Some studies suggest that echinacea could alter the effectiveness of some anticancer drugs or cause adverse effects.
Echinacea supplements available in stores contain varying amounts and different species of echinacea. Therefore, the beneficial results seen with echinacea in clinical trials may not apply to a product that contains a different species or quality of this herb. One study found that about half of the echinacea brands tested did not contain the type or quality of echinacea that they claimed on the label.
- To treat the common cold Most studies do not support this use. One clinical trial supports the use of echinacea for reducing the length of colds, but not the severity of symptoms. One large trial suggests a specific echinacea formulation could be as effective as a prescription drug to treat influenza, with fewer side effects.
- To stimulate the immune system Laboratory and animal studies suggest that echinacea extracts stimulate different parts of the immune system. Human studies suggest immune-changing effects.
- To treat viral infections Laboratory studies suggest that echinacea has antiviral properties and a human study suggests a specific echinacea formulation could be as effective as a prescription drug to treat the influenza virus.
- For faster wound healing Animal models suggest wound-healing properties, but studies have not been conducted in humans.
Do Not Take If
- You are taking drugs that are substrates of cytochrome P450: Echinacea may increase the risk of side effects of these drugs. Clinical relevance is not known.
- You are taking tamoxifen: Lab studies suggest echinacea may weaken the effects of tamoxifen. Clinical relevance is not known.
- You are taking etoposide: Echinacea caused low blood platelets in a patient receiving etoposide.
- You are taking P-glycoprotein (P-gp) substrate drugs: Lab studies suggest echinacea could alter effectiveness of some of these drugs. Clinical relevance is not known.
- You are taking oseltamivir: Lab studies showed that echinacea reduced the active formation of this drug, and may therefore reduce effectiveness. Clinical relevance is not known.
- You are taking immunosuppressants (eg, tacrolimus, cyclosporine): Echinacea may lessen their effect. Clinical relevance is not known.
Common: Headache, dizziness, nausea, constipation, mild stomach pain, skin rash, irritation
Rare: Serious allergic reactions
Case Reports – Oral
Worsening of a chronic blistering skin disease: In a 55-year-old man with a history of pemphigus vulgaris, which was controlled with immunosuppressants. Only partial remission was reported after he was treated again with immunosuppressants.
Reduced white blood cell count: In a 51-year-old woman following chronic use of echinacea. Her white blood cell count returned to normal levels 7 months after discontinuing echinacea supplements.
Severe hepatitis: In a 45-year-old man who complained of fatigue and jaundice lasting one week, linked to daily high doses of echinacea used to strengthen his immune system after catching the cold.
Increased eosinophil count in the bloodstream: In a 58-year-old man, there was an increase in this type of white blood cell following use of echinacea. His symptoms improved after discontinuing echinacea.
Low platelet and blood-coagulation disorders: Two case reports involve a 61-year-old cancer patient whose use of echinacea likely interacted with etoposide, and a 32-year-old man who used echinacea to alleviate respiratory symptoms.
Severe acute liver failure: In a 2-year-old girl, likely cause by echinacea toxicity.
Case Report – Topical
Eye irritation and conjunctivitis: 7 reports following use of topical echinacea were received by The National Registry of Drug-Induced Ocular Side Effects. Symptoms resolved after discontinuing echinacea.
For Healthcare Professionals
The genus Echinacea belongs to the family Compositae, commonly referred to as the sunflower family. Of the known species, E. purpurea, E. angustifolia, and E. pallida are commonly used in herbal medicine. Extracts derived from the root and aerial parts are widely used in Europe and the United States as nonspecific immunostimulants and to prevent or treat the common cold and influenza. However, natural products differ greatly in composition (26), mainly due to the use of different species, variable plant materials or extraction methods, and the addition of other components. Preclinical studies suggest immunostimulatory and anti-inflammatory effects (27). A standardized echinacea preparation inactivated influenza viruses (28) and may improve respiratory activity (2) (3). In animal models, echinacea stimulated erythropoiesis, increased blood-oxygen transport (29) (30), produced anxiolytic effects (31), and exhibited wound-healing properties (32) (33) (34).
Clinical data indicate that echinacea is ineffective in preventing the common cold caused by rhinoviruses (4) or in treating upper respiratory infections (5) (6) (16). Studies of its ability to reduce incidence and duration of the common cold yielded mixed results (7) (8) (9) (10) (22) (35) (36). Other analyses do not indicate any benefits for treating colds, and weak evidence for a prophylactic benefit (26) (37), but a large randomized trial found an echinacea formulation to be as effective as oseltamivir for influenza, and with fewer adverse events in the echinacea group (38). Small studies have shown that a standardized echinacea root extract has immunomodulating activity (39); an echinacea/sage spray was useful in treating acute sore throats (17); and a formula containing dry root extracts of Echinacea purpurea and Echinacea angustifolia may be useful as an adjuvant therapy for decreasing relapse incidence in patients treated for genital condylomatosis (67). Preliminary data on improving or enhancing athletic performance are mixed (40) (41). But a topical echinacea extract was reported effective in alleviating symptoms associated with atopic eczema (63). Echinacea may also have anticancer potential evidenced by the cytotoxic effects exerted by an extract and a major compound, cichoric acid, in human colon cancer cells (42).
Some studies suggest that echinacea could decrease plasma levels, affect therapeutic efficacy, or cause adverse effects with some anticancer drugs (25) (43). In HIV-infected patients, co-administration with etravirine was found to be safe and well tolerated (44). In a large population-based study, use of echinacea was associated with a slight increase in diastolic blood pressure (45). There is insufficient evidence regarding the efficacy and safety of echinacea during pregnancy (46).
Mechanism of Action
Echinacea’s active constituents include cichoric and caftaric acids, polysaccharides, and alkylamides (47). Immune-modulating effects of a standardized echinacea root extract include upregulation of interleukin (IL)-2 and IL-8 and downregulation of pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha and IL-6 (39). Immunemodulation by alkylamides occurs through binding to human cannabinoid receptors 1 and 2, and by inhibiting TNF-alpha (48). Alkylamides may also be responsible for anti-inflammatory effects (27). Although echinacea does not appear to have significant ergogenic or anabolizing effects, it appears to enhance the immune system and decrease oxidative damage (49).
In vitro and in vivo, echinacea extracts were shown to stimulate phagocytosis, enhance mobility of leukocytes, stimulate TNF and IL-1 secretion from macrophages and lymphocytes, and improve respiratory activity (2) (3). However, their effects on innate immunity such as phagocytosis could not be confirmed, and showed only minimal effects on tumor progression, although echinacea did stimulate natural killer cell activity (50). Other studies suggest that bacterial components of echinacea are responsible for immune benefits, as total bacterial load differences and content of bacterial lipopolysaccharides within echinacea samples have correlated with NF-kappaB activation in THP-1 cells (51).
In human colon cancer cells, cichoric acid decreased telomerase activity and induced apoptosis via DNA fragmentation, caspase-9 activation, poly-ADP-ribose polymerase (PARP) cleavage and beta-catenin downregulation (42). Differential effects of echinacea on intestinal and hepatic CYP3A activities may be due to systemic unavailability of locally-acting constituents that inhibit CYP3A, or rapid absorption of these constituents that limits intestinal exposure and CYP3A induction, or a systemically-formed constituent metabolite that is capable of inducing hepatic but not intestinal CYP3A (52).
- Patients undergoing chemotherapy should use caution with echinacea, as it may reduce the efficacy of some anticancer medications or cause adverse effects (25) (43) (53).
- Patients with allergies or asthma should exercise caution with echinacea, as allergic reactions have been reported (54).
- Patients undergoing blepharoplasty (eyelid surgery), should avoid echinacea because of added increased risk of dry eye syndrome (55).
Case Reports – Oral
Profound thrombocytopenia: In a 61-year-old man with nonsmall cell lung cancer who was concurrently taking echinacea while receiving chemoradiation with cisplatin and etoposide (25).
Severe thrombotic thrombocytopenic purpura (TTP): In a 32-year-old man following ingestion of echinacea to alleviate upper respiratory tract infection symptoms. TTP resolved after treatment for a month (18).
Pemphigus vulgaris exacerbation: In a 55-year-old man with a history of the condition which was controlled with immunosuppressants. Exacerbation was linked to consumption of echinacea, and only partial remission was regained after he was treated again with immunosuppressants (19).
Asymptomatic leukopenia: In a 51-year-old woman following chronic use of echinacea. Her white blood cell count returned to normal levels 7 months after discontinuing echinacea supplements (20).
Severe acute hepatitis: In a 45-year-old man who complained of fatigue and jaundice lasting one week, linked to the ingestion of daily high doses of echinacea used to strengthen his immune system after catching the cold (23).
Severe acute liver failure: In a 2-year-old girl, likely secondary to echinacea toxicity (56).
Hypereosinophilia: In a 58-year-old man following echinacea consumption, with symptoms improving after discontinuing echinacea (24).
Bilateral central facial palsy and severe quadriparesis: In a 25 year-old male after taking herbal drugs (containing echinacea and many other herbal ingredients) for two weeks. Symptoms improved after conventional treatment (64).
Acute cholestatic hepatitis: In a 41-year-old man following consumption of echinacea to strengthen immune system. His condition improved after discontinuing its use (65).
Case Reports – Topical
Eye irritation and conjunctivitis: 7 reports following use of topical echinacea were received by The National Registry of Drug-Induced Ocular Side Effects. Symptoms resolved after discontinuing echinacea (21).
Cytochrome P3A or CYP1A2 substrate drugs: Caution should be used when echinacea is coadministered with drugs dependent on CYP3A or CYP1A2 for their elimination (57). Clinical relevance is not known.
Tamoxifen: In vitro studies suggest concurrent echinacea use may result in subtherapeutic systemic exposure of prodrugs such as tamoxifen, reducing their efficacy (43). Clinical relevance is not known.
Etoposide: Echinacea caused profound thrombocytopenia in a patient receiving etoposide, likely due to the inhibition of CYP3A4 (25).
P-glycoprotein (P-gp) substrate drugs: In vitro, echinacea has been shown to inhibit P-gp activity (60), but the clinical significance of this is uncertain as echinacea supplementation in humans did not affect digoxin pharmacokinetics (61).
Oseltamivir: In vitro, echinacea reduced the formation of the active drug and may therefore reduce efficacy, but clinical significance is as yet undetermined (62).
Immunosuppressants: Echinacea may antagonize the effects of immunosuppressants (19). Clinical relevance is not known.