echinacea

Echinacea refers to a group of flowering perennial plants native to North America (found mainly east of the Rocky Mountains) that are botanically related to sunflowers and daisies. The three species most commonly used in supplements are Echinacea purpurea, E. angustifolia, and E. pallida. It has a history of traditional use among Native American peoples. Products are made from different parts of the plant and sold in forms such as capsules, tablets, teas, liquid extracts, and topical preparations.

According to NCCIH, the evidence on echinacea is weak and inconsistent. Taking echinacea may slightly lower your chances of catching a cold, but whether it can shorten how long a cold lasts remains unclear. For respiratory infections in children, one study suggested a possible benefit, but overall there isn't enough evidence to support a clear connection. It is also unclear whether echinacea helps with other conditions, including eczema. Findings are difficult to compare across studies because echinacea products differ widely in the species, plant parts, and preparation methods used.

There is no established standard dose. Because products vary substantially in species, plant part, and how they are prepared, the strength of one product can differ greatly from another. Echinacea has generally been studied only for short-term use. Talk with your doctor, pharmacist, or another qualified health professional before starting echinacea, especially if you are pregnant or breastfeeding, considering giving it to a child, take other medications, or have a health condition.

NCCIH indicates that products containing E. purpurea extracts (and some mixtures of E. purpurea and E. angustifolia) are likely safe for most adults to use for short periods, and that E. purpurea extract is possibly safe for children short-term. However, some people have allergic reactions to echinacea that may be severe. Echinacea is botanically related to plants such as ragweed and daisies, so caution may be warranted if you are sensitive to related plants, though the source does not establish this as a confirmed risk factor. Some children in a clinical trial developed rashes that may have been allergic reactions. Long-term safety has not been well established.

The most commonly reported side effects are digestive symptoms, such as abdominal pain, stomach pain, and nausea. Allergic reactions can also occur and may be severe, including rashes. Seek medical care promptly for signs of a serious allergic reaction.

NCCIH notes there is conflicting evidence about whether echinacea interacts with some drugs that are metabolized by the liver. There are also theoretical reasons to suspect it might interact with immunosuppressant medications or with caffeine. Tell your clinician and pharmacist about all medications and supplements you take before using echinacea.