Echinacea is an herbal remedy people often use to treat the common cold. Many people believe that the plant can boost the immune system and reduce the severity or length of colds. Echinacea is one of the best-selling herbal products in the U.S.
But despite its popularity, some recent studies of echinacea for the common cold have not found that it helps. If echinacea does have a benefit, many researchers feel that it has not been proven.
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Echinacea is a flowering plant that grows throughout the U.S. and Canada. There are nine species. Some of the plant's common names are the purple coneflower or black-eyed Susan. The leaves, stems, flower, and roots may be used to produce supplements, liquid extracts, and teas. People have used echinacea as a remedy in the Americas for centuries.
Echinacea for the Common Cold: Does It Work?
Studies of echinacea for the common cold have had mixed results. Extracts of echinacea do seem to have an effect on the immune system. Studies have shown that it increases the number of white blood cells and boosts the activity of macrophages, a subset of white blood cells. A review of more than a dozen studies on the prevention and treatment of cold with echinacea, published in 2014, found a very slight preventive benefit of echinacea.
Two studies funded by the National Center for Complementary and Alternative Medicine also did not find any benefit from echinacea for the common cold in either children or adults.
However, there are many variables in studying echinacea for the common cold. Studies have looked at different types and strengths of echinacea as well as different parts of the plant or root. This makes it hard to compare the results. It's possible that some formulations are better than others. Echinacea may also help against some viruses that cause colds.
Are There Side Effects of Echinacea for the Common Cold?
Although the benefits of echinacea for the common cold are in doubt, the risks seem to be low. The most common side effect is upset stomach.
Some people have allergic reactions to echinacea. This can cause:
Worsening asthma (if you have asthma)
Anaphylaxis (a life-threatening emergency that can cause difficulty breathing)