Echinacea

Echinacea. Source: Wikimedia Commons (Jacob Rus)

Echinacea species are perennials that belong to the Aster family. Echinacea purpurea is commonly used medicinally, and probably has the most potent extracts. Echinacea contains nine known species, all of which are native to the United States and southern Canada.

Other Names

Common Names

• echinacea
• purple coneflower
• coneflower
• American coneflower

Latin Names

• Echinacea purpurea
• Echinacea angustifolia
• Echinacea pallida

Sources

The aboveground parts of the plant and roots of echinacea are used fresh or dried to make teas, squeezed (expressed) juice, extracts, or preparations for external use.

Uses

Echinacea is believed to stimulate the immune system. Accordingly, traditional uses of Echinacea include the prevention and treatment of colds, flu, and other infections. Less commonly, echinacea has been used for wounds and skin problems, such as acne or boils.

How Echinacea is Taken

Echinacea is commercially available as capsules, juice, extract, tea, and tincture. Some studies indicate that it can be taken by mouth three times a day for up to seven days at a dose of 500 mg to 1,000 mg (milligrams). The dose required to have an effect, if an effect can be seen, is not known.

Use of echinacea for a maximum of six to eight weeks reduces the risk of developing side effects and complications.

How Echinacea Works

Laboratory studies have shown that echinacea has numerous effects on immune cells. Echinacea stimulates the production of T cells and interferon, which is a protein that stimulates the immune system. It also stimulates internalization of foreign bodies by immune cells to remove them from the circulation and increases the ability of immune cells to move to the site of an infection.

Side Effects

• When taken by mouth, echinacea usually does not cause side effects. However, some people experience allergic reactions, including rashes, increased asthma, and anaphylaxis (a life-threatening allergic reaction). In clinical trials, gastrointestinal side effects were most common.
• People are more likely to experience allergic reactions to echinacea if they are allergic to related plants in the daisy family, which includes ragweed, chrysanthemums, marigolds, and daisies. Also, people with asthma or atopy (a genetic tendency toward allergic reactions) may be more likely to have an allergic reaction when taking echinacea.

Precautions

Not everyone should take echinacea. People with tuberculosis, HIV/AIDS, multiple sclerosis, or other autoimmune diseases should avoid using echinacea.

Clinical Trials

The effectiveness of Echinacea in treating the common cold is controversial. Studies indicate that echinacea does not appear to prevent colds or other infections. To date, the results of trials have shown that Echinacea does not shorten the course of colds or flu. For example, two studies funded by the National Center for Complementary and Alternative Medicine (NCCAM) did not find a benefit from echinacea, either as Echinacea purpurea fresh-pressed juice for treating colds in children, or as an unrefined mixture of Echinacea angustifolia root and Echinacea purpurea root and herb in adults.^[1][2] However, other studies have shown that echinacea may be beneficial in treating upper respiratory infections.^[3] To help settle the controversy, an analysis was performed on 22 clinical trials of Echinacea and the common cold.^[4] None of the trials showed that Echinacea prevented colds. Nine trials showed that Echinacea was an effective treatment for colds, and six studies showed that it had no beneficial effect. The authors conclude that the results show promise, but much more study is needed, especially in well-designed trials. Taking this analysis into account, a review of various treatments for the common cold concluded that Echinacea is an ineffective cold treatment.^[5]

References

1. ↑ Taylor JA, Weber W, Standish L, et al. Efficacy and safety of echinacea in treating upper respiratory tract infections in children: a randomized controlled trial. JAMA. 2003 Dec 3;290(21):2824-30. Abstract | Full Text
2. ↑ Barrett BP, Brown RL, Locken K, et al. Treatment of the common cold with unrefined echinacea: a randomized, double-blind, placebo-controlled trial. Ann Intern Med. 2002 Dec 17;137(12):939-46. Abstract
3. ↑ Fugh-Berman A. Echinacea for the prevention and treatment of upper respiratory infections. Seminars in Integrative Medicine. 2003;1(2):10611.
4. ↑ Linde K, Barrett B, Wölkart K, Bauer R, Melchart D. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. 2006 Jan 25;(1):CD000530. Abstract
5. ↑ Simasek M, Blandino DA. Treatment of the common cold. Am Fam Physician. 2007 Feb 15;75(4):515-20. Abstract | Full Text

Echinacea. In: Blumenthal M, Goldberg A, Brinckman J, eds. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Lippincott Williams & Wilkins; 2000:88–102.

External Links

Echinacea. Natural Medicines Comprehensive Database Web site.