Common colds: Does echinacea work?

It is not clear whether echinacea extracts can prevent colds. Some echinacea products might help to reduce the length and severity of a cold if taken at the very beginning. Because the available products are very different to one another, more research is needed. Adverse effects are rare.

Echinacea is a plant that is a popular treatment for the common cold. The wide variety of echinacea products available differ in strength and content, depending on which species or part of the plant they use (leaves, roots, flowers or whole plants), how the plant is processed and whether the product includes other ingredients. This means that there is no guarantee that the products that you can buy have the same effect as the few that have been tested in trials. Echinacea products are available in the form of drops, liquids, capsules and tablets.

Research on echinacea

A group of researchers from the Cochrane Collaboration – an international network of researchers – reviewed trials that tested echinacea products. They wanted to know whether echinacea can effectively prevent or treat the common cold. They were also interested in whether any of the products help more than others.

People usually recover from colds quite quickly, with or without treatment. This means that it is not easy to tell whether or not a particular treatment has worked. So the researchers only looked for so-called randomised controlled trials (RCTs). You can read about how these trials are done and why they provide the most reliable results here.

The researchers found 16 trials comparing echinacea with a dummy treatment (a placebo), two comparing it with no treatment, and one trial comparing it with a different type of herbal preparation. Most trials looked at its effectiveness in treating colds, but three looked at whether echinacea could prevent colds. Although some of the trials were of high quality, they tested a lot of different types of echinacea treatments, so it was difficult to summarise the results and get an overall picture of the effects of this plant.

Echinacea might relieve the symptoms of a cold

Some of the trials suggest that products using the flowers and leaves of one type of echinacea (Echinacea purpurea) might help in the early stages of colds in adults. However, not all of the trials came to the same conclusion. Those that looked at prevention did not find that echinacea products can prevent colds. There are currently not enough trials to say for sure whether echinacea really does prevent colds, or at least relieve the symptoms.

The different echinacea products rarely had adverse effects. If any did arise, they were usually nausea or rashes. In one study, children were found to have more rashes, which may have been caused by an allergic reaction. Although allergies to echinacea are rare, some researchers believe that people who have other allergies or asthma should be aware of the allergy risk when using echinacea.

A lot of people take echinacea products for long periods of time. In Germany, the drug regulatory authorities recommend that echinacea products not be taken for longer than a certain length of time, which varies from product to product. To find out the recommended maximum time period for a particular product, read the package insert or ask your doctor or pharmacist. According to the Cochrane review, there are no trials in which people took echinacea products for longer than 12 weeks, so the long-term effects are not clear.

You can read more about the common cold in our feature. Find out what you can do to protect yourself and your family from respiratory viruses in our fact sheet.


Author: German Institute for Quality and Efficiency in Health Care (IQWiG)

© IQWiG (Institute for Quality and Efficiency in Health Care)