Echinacea

Echinacea is said to stimulate the immune system. When taken at the start of a cold, it is said to shorten the duration of cold symptoms. Well-designed studies have not supported this effect. Echinacea is said to stimulate the immune system. When taken at the start of a cold, it is said to shorten the duration of cold symptoms. Well-designed studies have not supported this effect.

Topical preparations are used to promote wound healing.

Studies of echinacea's role in preventing and/or treating the common cold are inconsistent. The largest factor contributing to inconsistency is the variability of plant preparations (including different plant parts and species) and ultimately composition of the supplement. Studies of echinacea's role in preventing and/or treating the common cold are inconsistent. The largest factor contributing to inconsistency is the variability of plant preparations (including different plant parts and species) and ultimately composition of the supplement.

A 2014 Cochrane review of 24 studies (4631 participants) evaluated a variety of different echinacea products to prevent or treat colds (A 2014 Cochrane review of 24 studies (4631 participants) evaluated a variety of different echinacea products to prevent or treat colds (1). No benefit was shown for prevention, although a post hoc pooling of prevention studies implied a 10 to 20% relative risk reduction. The authors concluded some products had weak benefit . A subsequent meta-analysis of randomized trials assessed the impact of echinacea on prevention, duration, and safety for upper respiratory tract infections (). No benefit was shown for prevention, although a post hoc pooling of prevention studies implied a 10 to 20% relative risk reduction. The authors concluded some products had weak benefit . A subsequent meta-analysis of randomized trials assessed the impact of echinacea on prevention, duration, and safety for upper respiratory tract infections (2). There was a significant effect on prevention but no impact on symptom duration and no safety risk. However, a limitation was heterogeneity of included studies.

A randomized trial including 200 healthy children found that echinacea use prevented respiratory infections and reduced antibiotic prescriptions by 76.3% (A randomized trial including 200 healthy children found that echinacea use prevented respiratory infections and reduced antibiotic prescriptions by 76.3% (3).

In vitro studies have evaluated the impact on immune cells of the proteobacteria activity intrinsic in echinacea plants, as well as the soil composition where it is grown (In vitro studies have evaluated the impact on immune cells of the proteobacteria activity intrinsic in echinacea plants, as well as the soil composition where it is grown (4, 5). However, more research is needed to evaluate impact in humans.

Most adverse effects are mild and transitory; they include dizziness, fatigue, headache, and gastrointestinal symptoms. Echinacea should be avoided in patients with autoimmune disorders, multiple sclerosis, advanced HIV infection, tuberculosis, and organ transplants because it may stimulate T cells. Allergic reactions are possible in patients with allergies to ragweed, chrysanthemum, marigold, daisies, or related allergens.Most adverse effects are mild and transitory; they include dizziness, fatigue, headache, and gastrointestinal symptoms. Echinacea should be avoided in patients with autoimmune disorders, multiple sclerosis, advanced HIV infection, tuberculosis, and organ transplants because it may stimulate T cells. Allergic reactions are possible in patients with allergies to ragweed, chrysanthemum, marigold, daisies, or related allergens.

Echinacea inhibits some cytochrome P-450 enzymes and induces some enzymes; it can therefore potentially interact with medications metabolized by the same enzymes (eg, anabolic steroids, azole antifungals, methotrexate, etoposide, and other chemotherapeutic agents). Echinacea inhibits some cytochrome P-450 enzymes and induces some enzymes; it can therefore potentially interact with medications metabolized by the same enzymes (eg, anabolic steroids, azole antifungals, methotrexate, etoposide, and other chemotherapeutic agents).

(See also table Some Possible Dietary Supplement–Medication Interactions.)

1. 1. Karsch-Volk M, Barrett B, Kiefer D, et al. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. (2) CD000530, 2014. doi: 10.1002/14651858.CD000530.pub3

2. 2. David S, Cunningham R: Echinacea for the prevention and treatment of upper respiratory tract infections: a systematic review and meta-analysis. : Echinacea for the prevention and treatment of upper respiratory tract infections: a systematic review and meta-analysis.Complement Ther Med 44:18-26, 2019. doi: 10.1016/j.ctim.2019.03.011

3. 3. Ogal M, Johnston SL, Klein P, Schoop R. Echinacea reduces antibiotic usage in children through respiratory tract infection prevention: a randomized, blinded, controlled clinical trial. . Echinacea reduces antibiotic usage in children through respiratory tract infection prevention: a randomized, blinded, controlled clinical trial.Eur J Med Res. 2021 Apr 8;26(1):33. doi: 10.1186/s40001-021-00499-6

4. 4. Haron MH, Tyler HL, Pugh ND, Moraes RM, Maddox VL, Jackson CR, Pasco DS. Activities and Prevalence of Proteobacteria Members Colonizing Echinacea purpurea Fully Account for Macrophage Activation Exhibited by Extracts of This Botanical. . Activities and Prevalence of Proteobacteria Members Colonizing Echinacea purpurea Fully Account for Macrophage Activation Exhibited by Extracts of This Botanical.Planta Med. 2016 Sep;82(14):1258-65. doi: 10.1055/s-0042-108590.

5. 5. Haron MH, Tyler HL, Chandra S, Moraes RM, Jackson CR, Pugh ND, Pasco DS. Plant microbiome-dependent immune enhancing action of Echinacea purpurea is enhanced by soil organic matter content. . Plant microbiome-dependent immune enhancing action of Echinacea purpurea is enhanced by soil organic matter content.Sci Rep. 2019 Jan 15;9(1):136. doi: 10.1038/s41598-018-36907-x

The following English-language resource may be useful. Please note that The Manual is not responsible for the content of this resource.

1. National Institutes of Health (NIH), National Center for Complementary and Integrative Health: Echinacea