While the coronavirus is unquestionably the most newsworthy virus this year, winter is prime time for other viruses that cause upper respiratory infections such as the common cold, the flu and others.
For centuries, humans have looked to natural and herbal remedies for these illnesses. At the top of that list is echinacea. This plant, also known as purple coneflower, coneflower and American coneflower, was used by Native Americans of the Great Plains as a traditional medicine, according to the National Center for Complementary and Integrative Health, part of the National Institutes of Health.
Echinacea continues to be used today. But does it work?
Echinacea, a member of the daisy family, goes by such Latin names as Echinacea purpurea, Echinacea angustifolia and Echinacea pallida. There are nine known species of echinacea, all them native to North America and many of them familiar to gardeners because of their colorful and pleasing flowers.
E. purpurea, E. pallida and E. angustifolia are the species most commonly used in dietary supplements, according to the NCCIH. “Echinacea is somewhat unique in that there are three separate species that all go by the common name echinacea, but may have different activity profiles,” says Craig Hopp, deputy director of the division of extramural research at NCCIH.
Echinacea is promoted as a dietary supplement for the common cold and other respiratory infections because it is believed to stimulate the immune system to fight those infections more vigorously. Echinacea preparations have also been used in topical treatments for wounds and skin problems, but they are primarily used for immune-boosting abilities against colds.
But the science behind that belief is inconclusive. “Taking echinacea might slightly reduce your chances of catching a cold,” Hopp says. “There isn’t enough evidence to show whether echinacea is helpful for other health conditions.”
Hopp hedges because some preparations of echinacea are more effective than placebo for treating colds, according to the NCCIH. Although many studies have been done on echinacea for the common cold and other upper respiratory tract infections, the overall evidence for clinically relevant treatment effects is weak. Individual trials consistently show positive but not significant trends, and “potential effects are of questionable clinical relevance,” the NCCIH reports.
The reason for this may be that studies about most herbal remedies, including echinacea, tend to be highly variable, says Dr. Bianca Chiara, a family medicine physician certified by the Institute for Functional Medicine who practices at the Chambers Center for Well-Being, part of Atlantic Health System in Morristown, New Jersey.
Chiara mentions, among other studies, a 2007 meta-analysis in the journal Lancet that found echinacea lowered the odds of getting a cold by 58% and shortened the duration of a cold by 1.4 days. The problem with herbal studies often resides in the fact that so much is not standardized, such as the specific species of herb, the dosage, the parts of the plant used and other factors. “You can see how it’s easy for studies to be all over the place,” she says.
Some studies in individual cells have shown that a one brand of echinacea supplement did improve immune response and antiviral activity, and they teased out a few of the biochemicals that may be responsible for that. A 2016 study suggests that the effect of echinacea on immune cells may depend on the types and amounts of bacteria within the echinacea plant. The effects may come from any number of “constituents,” Chiara says. “We definitely don’t know all the active constituents in echinacea.”
For most adults, echinacea is probably safe in the short run, according to the NCCIH, but long-term use is unknown. Similarly, only preliminary research has looked into taking echinacea during pregnancy, and its safety during pregnancy or while breastfeeding is also uncertain.
The most common side effects of echinacea are nausea, stomach pain or other digestive issues. The NCCIH reports that some people have allergic reactions to echinacea, which may be severe. E. purpurea may be associated with an increased risk of rash in children, as some children developed rashes during a clinical trial, which may have been caused by an allergic reaction. There is a low risk of interactions between echinacea supplements and most medications. The only caveat may be someone taking immunosuppressant medications, Chiara says.
Chiara thinks the evidence is strong enough for most people to at least give echinacea a try for a short time. But be sure to consult your doctor beforehand. “The most typical way is to take it two to three times a day for seven to 14 days at the very onset of cold symptoms or if you had direct exposure to someone who has a cold,” she says. It can be taken as a capsule, a tincture or in a tea blend. For most people, like chicken soup, it couldn’t hurt.
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