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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.

Why do people take echinacea?

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

So far, evidence suggests that echinacea may prevent the common cold. It also might help as a treatment. 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.

How much echinacea should you take?

There is no standard dose of echinacea. It depends in part on the form you use. For example, the usual dose range for pressed juice is 6-9 milliliters daily, and the usual dose range for tinctures (usually a solution of alcohol and herbal extract) is 0.75-1.5 milliliters daily. Standardized extracts have other specific doses. Some people use echinacea tea, 6-8 ounces, four times daily. Echinacea appears to be most effective when started as soon as symptoms are noticed, taken many times a day, and used for seven to 10 days. It is possible that liquid forms of echinacea (such as alcohol or glycerin-based tinctures) might work better than capsules -- as they’re being swallowed, these liquids could have an antiviral effect on the mucous membranes of the back of the throat.

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