Echinacea for colds and flu

Echinacea. Its the first thing that many people take when they feel a cold coming on. Many people even take it throughout the winter months to prevent a cold from starting. So what evidence is there for the use of this popular herb as a cold remedy?

Traditional uses of Echinacea

Echinacea, or purple coneflower, grows across the continental United States. It was traditionally used by Native Americans for a variety of ailments, as an antiseptic and antibiotic, to treat skin wounds; it was useful for toothache, relieving sore throats and as a cure for snakebite. The first English settlers used it for treating saddle sores. As for it having a traditional use for colds, one source reports that only the Crow Indians used Echinacea for treating colds and upper respiratory infections (1), another (2) that only the Cheyenne,did so. It certainly appears that the modern indication of Echinacea for colds was not commonplace among the different Native American groups.


Echinacea was described, in the 1898 King’s Medical Dispensary, as follows: “Though now a well-known drug, echinacea stands peculiarly alone in being essentially a new remedy. Many remedies which have lately been introduced can be traced back for years, and some of them for centuries, as having at some time occupied a place in either domestic or professional practice, but our ancient scientific works are silent concerning this species of echinacea.”(3)

Popularisation of Echinacea

The sense that it was a ‘new’ remedy may have arisen because in the 1870s, a doctor, one H.C.F. Meyer, ‘rediscovered’ Echinacea and popularized it as a cure for snakebites, claiming that he had never had a case of snakebite that it couldn’t cure. Within 20 years, it had become the most popular herb in the USA (4).

There was some initial confusion as to which species of Echinacea was to be used. Gray, in the Synoptical Flora of North America (5), wrote that Echinacea was “Used in popular medicine under the name Black Sampson”, but that name referred to Echinacea purpurea. Meyer had actually based his remedies on Echinacea angustifolia, an altogether different, narrow leafed species. To this day, many people are unaware of a difference and do not appreciate that not all Echinacea products are alike.

For much of the following decades and the early part of the 20th century, Echinacea was used for everything but colds. Boericke’s Materia Medica (1901) recommended it for blood poisoning, sepsis, gonorrhea, boils, gangrene, cankers, ulcers, heartburn and as anti venom, among other possible uses (6). Such claims or Echinacea far exceeded the available evidence. By way of an example, Ellingwood wrote in 1919 that Echinacea was effective for treating rabies, although he did express some skepticism:

“By far the most difficult reports to credit are those of the individuals bitten by rabid animals; there are between twenty and thirty reports at the present time. In no case has hydrophobia yet occurred, and this was the only remedy used in many of the cases.” (7)

Over 100 years later, rabies remains an exceptionally intractable disease. Survival depends on getting a rabies vaccination as soon as possible after being bitten; by the time symptoms appear, it is too late. Yet in 1919, he reported that Echinacea was an effective rabies cure:

“One case exhibited the developing symptoms of hydrophobia before the agent was begun. They disappeared shortly after treatment.”

Use by the medical establishment

Echinacea was widely used by physicians, especially the Eclectics, and had begun to attract research interest. In 1915, a New York physician named Victor von Unruh showed that Echinacea increased the phagocytic power of leukocytes (the white blood cells). He went on to report that Echinacea improved hyperleukocytosis (too many white blood cells) and leukopenia (too few white blood cells).

Lets take a look at that. Two such contradictory findings as these raise an important question: viz., is it an immune system stimulator, or an immune system suppressant? In fact this looks like a simple case of what is known as ‘regression to the mean’. An unusually high leukocyte count, over time, can be expected to fall back to a normal level. An unusually low leukocyte count, over time, may also be expected to return to normal levels. This return to the mean, or average, values, can occur whether treated with Echinacea or not, an explanation more plausible than that of a mysterious leukocyte balancing effect for Echinacea; the changes in white blood cell counts occurred independently of the treatment.

Weak though this evidence may have been, by the end of the 1920s, Eclectics such as Liebstein, writing in 1927, were praising Echinacea’s powers as an immune system stimulant in glowing terms: “Nature has probably destined Echinacea to be used for remedial purposes only, as a sustainer of vitality, an organizer of the defensive powers of the system, to such an extant as to be justly crowned the greatest immunizing agent in the entire vegetable kingdom, as far as is known to medical science” (8).

Echinacea becomes popular in Europe

From the late 1930s onwards, research into Echinacea began to take off in Germany, even as its use declined in the United States. In an unusual twist of circumstance, Dr Gerhard Madaus had procured a batch of what he thought was Echinacea angustifolia seeds, with the intention of cultivating them in Germany, but turned out to be the seeds of the different but closely related species Echinacea purpurea. Extracts of the plant flowers are sold to this day by Madaus under the name Echinacin. As a consequence, much of the European research on Echinacea has been conducted on the Echinacin extract from E. purpurea, and not the E. angustifolia species that had been in widespread use in the USA.

Numerous studies, many from the Madaus research labs, demonstrated the effects of Echinacin on a broad spectrum of diseases. See (8) for a comprehensive overview of such research. The areas of investigation included its topical use in wound healing, high dose injections of Echinacin for inhibiting streptococcus and pertussis, and various attempts to identify the modes of action and the active ingredients of the plant extract. Some of these later studies appeared to confirm von Unruh’s first conclusion; that Echinacea can  potentially stimulate the immune system. However, as interesting as these studies were, only a few had the statistical power of the placebo controlled double blind trial, and fewer still were undertaken on human subjects. This is a critically important consideration if we are interested in the evidentiary base for the current use of Echinacea, which is as an immune system stimulant and a treatment for preventing or shortening the duration of the common cold.

Echinacea as a cold cure

While there have been many decades of research into Echinacea, what I have so far been unable to find is the smoking gun, a study that first linked Echinacea to treating colds. At some point in the past few decades, Echinacea entered the popular lexicon as a cold treatment and immune stimulant; perhaps it was the accumulation of all of these in vitro and high dose studies that created the idea.

In 1999, the respected Cochrane Collaboration reviewed the evidence for using Echinacea for preventing and treating the common cold, based on 16 different published trials (9). While doing so, the reviewers ran up against a few obstacles. First, the extracts in common use can come from different species (E. angustifolia, E. purpurea or E. pallida). Secondly, extracts can be made from different parts of the plant. Echinacin is an extract of the aerial parts of E. purpurea. Other extracts are made from the plant root. Different extraction methods can be used, such as drying, alcohol extraction or pressing, so one can’t assume that all of these different sources and preparations will yield an identical herbal remedy. I’ll quote their findings here.

“We reviewed 16 controlled clinical trials investigating the effectiveness of several different Echinacea preparations for preventing and treating common colds. Two trials investigated whether taking Echinacea preparations for 8 to 12 weeks prevents colds but found no clear effect. The majority of trials investigated whether taking Echinacea preparations after the onset of cold symptoms shortens the duration or decreases the severity of symptoms, compared with placebo. It seems that some preparations based on the herb of Echinacea purpurea might be effective for this purpose in adults, while there is no clear evidence that other preparations are effective or that children benefit. Side effects were infrequent but rashes were reported in one trial in children.”

Their analysis was hardly a ringing endorsement. They found that extracts of E. purpurea may have been more beneficial than E. angustifolia or E. purpurea, but it was far from clear. A later meta-analysis, published in 2005, looked at the quality of nine studies of Echinacea as a cold treatment. Six of the studies found that Echinacea had any benefit, and three found that it did not. Of the positive trials, none met the quality criteria, whereas two of the negative studies did so. In particular, the blinding procedures were inadequate, as the extract has a distinctly bitter taste and patients could potentially identify if they were receiving the placebo or the extract (10).

Later still, a meta-analysis in 2007 concluded that, based on 14 studies, “echinacea has a benefit in decreasing the incidence and duration of the common cold; however, large-scale randomised prospective studies controlling for variables such as species, quality of preparation and dose of echinacea, method of cold induction, and objectivity of study endpoints evaluated are needed before echinacea for the prevention or treatment of the common cold can become standard practice. (11)”.

100 years of research into Echinacea

Let’s review the field. Almost a century after laboratory studies on Echinacea began in earnest, its popular use has transformed from that of being a snakebite and sepsis cure to that of immune system stimulant and a treatment for the common cold. A number of in vitro studies support the immuno-stimulant effect, although there is a deficit of clinical data to support such a use in clinical practice. The evidence for its use as a cold treatment is decidedly mixed; many clinical trials were of too poor quality to reach a definitive conclusion; one meta-analysis found some supporting evidence, in contrast to other meta analyses, including a Cochrane review, that found little. Even after all this time, there exists no consensus on the plant part to use, the plant species, the best extraction method or the effective dose. The specific components of Echinacea that supposedly treat the common cold have not been identified, beyond a vaguely worded immuno-stimulant effect.

This traditional remedy, at one time a wound treatment, antiseptic, snake bite cure, and general cure all, could still hold surprises. There may be an optimal preparation, or species, or extract of Echinacea for treating a cold, but nobody yet knows what that is. Lack of knowledge of which preparations are most effective, as well as poor study quality, are factors that may go a long way to explaining the very mixed results for Echinacea as a cold treatment. Other indications, such as wound healing, one of its traditional uses, could prove to be more appropriate and successful, but given its current popularity as a cold treatment, research into colds will predominate.

At the present time, I am far from convinced that an over the counter, low dose preparation of Echinacea would have any benefit over placebo. However, I’ll go this far: taking Echinacea at the onset of a cold could mean getting better within just seven days, rather than one week.

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1 Lewis, W.H. & Elvin- Lewis, M.P.F. (2006). Medical Botany- Plants affecting human health, 2nd edition, John Wiley & Sons INC, Hoboken, New Jersey

2 http://www.naturalmedicinesofnc.org/Echinacea/Echinacea-history.html

3 King’s American Dispensatory, 1898

4 Echinacea: Nature’s Immune Enhancer, Stephen Foster, 1991

5 Synoptical flora of North America. Asa Gray (undated)

6 Boericke’s Materia Medica, 1901

7 The American Materia Medica, Therapeutics and Pharmacognosy, 1919, Finley Ellingwood, M.D.

8 Echinacea: Nature’s Immune Enhancer. Steven Foster. Published by Inner Traditions / Bear & Company, 1990

9 Linde K, Barrett B, Bauer R, Melchart D, Woelkart K. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD000530. DOI: 10.1002/14651858.CD000530.pub2.

10 Caruso TJ, Gwaltney JM (2005). “Treatment of the common cold with echinacea: a structured review”. Clin. Infect. Dis. 40 (6): 807–10. doi:10.1086/428061

11 Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infectious Diseases 2007; 7: 473–80

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