Medically Reviewed by Arefa Cassoobhoy, MD, MPH on May 27, 2023

Echinacea has been long used to fight colds and infections, and many experts recommend its use. It is one of the most popular supplements in the U.S.

Many people take echinacea in the hopes that it will boost immunity. Studies have had mixed results.

So far, evidence suggests that echinacea may slightly decrease your chance of catching common cold. But it has not been foud to shorten the length of a cold once you have one. Some studies, many of them small, have found that taking echinacea may reduce the length of a cold and the severity of its symptoms. However, two large clinical trials found no benefits at all.

It’s important to note that there are different species of echinacea, such as Echinacea purpurea, Echinacea pallida, and Echinacea angustifolia. Some of the conflicting findings may result from researchers testing different varieties. The strongest evidence for echinacea as a cold treatment comes from studies of Echinacea purpurea. Studies of Echinacea angustifolia and any echinacea root have had weaker results. Echinacea may not work as well in children and young adults as it does in older adults.

When taken along with an antifungal cream, oral echinacea may help prevent recurrent vaginal yeast infections. While some studies suggest that echinacea may slightly reduce flu symptoms, the evidence isn't clear.

Echinacea does not seem to help prevent or treat herpes. The effect of echinacea on other conditions is not known.

Recommended dosages of echinacea differ widely depending on the product. The most commonly used preparation in the United States is a liquid extract of E. purpurea root; typical dosing of such a preparation would be 3 mL every three to four hours for the first one to two days of upper respiratory illness, then three times daily for the subsequent week. Patients who are using an echinacea tea (made from E. angustifolia or E. purpurea root) will need to take higher dosages, typically 6 to 8 oz four times daily for the first two days, titrating down to once or twice daily on days 3 to 7.

There are no natural food sources of echinacea.

  • Side effects. When taken at normal doses, echinacea causes few side effects. Some people have reported symptoms like upset stomach, headache, sore throat, drowsiness, and rash.
  • Risks. Although rarely, echinacea can cause allergic reactions. Some can be serious. If you have asthma or an allergy to certain plants and flowers -- like ragweed, chrysanthemums, marigolds, or daisies -- be cautious when using echinacea. Taking echinacea by injection is dangerous. Check with a doctor before using echinacea if you have an autoimmune disease like lupus, rheumatoid arthritis, MS, or if you have HIV.
  • Interactions. If you take any drugs regularly -- particularly drugs that suppress the immune system -- talk to your doctor before you start using echinacea supplements. There is also some concern that echinacea could cause liver problems in people who are also taking certain painkillers like acetaminophen (Tylenol), antidepressants, blood thinners, sedatives, and other drugs.

Given the lack of evidence, children and pregnant or breastfeeding women should not take echinacea unless their doctors have approved it.

Show Sources


Longe, J., ed. The Gale Encyclopedia of Alternative Medicine, second edition, 2004.

Memorial Sloan-Kettering Cancer Center web site: "About Herbs: Echinacea."

National Center for Complementary and Alternative Medicine web site: "Herbs at a Glance: Echinacea."

Natural Medicines Comprehensive Database web site: "Echinacea."

Natural Standard Patient Monograph: "Echinacea."

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