Can this flower tackle the common cold?

The Irish Times
Health Supplement, p. 13
1 April 2008

DOES IT WORK?: Is echinacea any use against the common cold?

ECHINACEA IS a very popular herbal remedy that comes into its own during the cold and flu season.

On average, adults get between two and four colds a year, with children getting between six and 10. Studies in the US have found that colds lead to 40 per cent of lost work time and 30 per cent of lost school time. Despite the annoyance and cost of colds, few things seem to help other than hot drinks and rest. Antibiotics are best avoided for treating colds, as they are ineffective and overuse has many negative consequences.

Instead, should we be trying echinacea? This is a group of nine related plants, of which three are commonly used in herbal remedies. The most commonly used species is also called purple coneflower and is grown in gardens for its radiant flowers at the end of tall stems. The plants were first used by native Americans in North America for treating various infections and snakebites.

Evidence from studies

The most recent systematic review of echinacea research found 16 different controlled studies. However, these used different echinacea species, different parts of the plants, and different doses. As might be expected, the results varied widely. About one-third of the studies found echinacea no better than a placebo, while about two-thirds found some benefit. However, some general patterns did emerge. For treating the common cold, a small but relatively consistent benefit was found. Echinacea reduced the severity and duration of the symptoms by about 10 to 30 per cent.

Practically speaking, this means that the symptoms were a little milder and gone about a day to a day-and-a-half sooner than for those taking placebo. The most effective species, and the one traditionally used, was echinacea purpurea. It is most commonly used by starting it immediately after noticing the cold symptoms and using it continuously for seven to 10 days.

Much less evidence exists to support using echinacea to prevent colds. Two studies found it reduced the numbers of colds a person got, but one of these involved athletes training vigorously and the other used echinacea along with other dietary supplements, including vitamin C. The majority of studies found that echinacea did not reduce how many colds people got when taking it continuously.

Echinacea is also recommended for the flu, but very little research has been conducted in this area. The evidence does not exist to make recommendations here.

Problematic aspects

Echinacea appears to have few adverse effects. It can lead to stomach and intestinal problems in some people, and can cause allergic reactions.

Echinacea belongs to the aster or daisy family of plants. Anyone allergic to these flowers should be cautious with echinacea. The most common allergic reactions are skin rashes, sinus problems and irritated throat and mouth, which can be misinterpreted as cold symptoms. If an allergic reaction is suspected, taking echinacea should be stopped.


For those who are generally healthy, the common cold is annoying and bothersome, but will be gone soon. That doesn’t stop the search for some relief, but it makes the testing of potential treatments challenging. The placebo effect is more powerful with such conditions, making it difficult to know how much benefit any particular remedy provides.

Given that most studies show echinacea is somewhat beneficial, and that it is generally safe, it appears to be a useful option. However, it isn’t likely that it is going to prevent the common cold, and it doesn’t cure it immediately. Neither does it take the place of getting some rest and drinking plenty of fluids.
Back to Herbal Remedies list

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