Echinacea Side Effects and Warnings

Safety Issues

Echinacea appears to be generally safe. Even when taken in very high doses, it has not been found to cause any toxic effects. ¹ Reported side effects are also uncommon and usually limited to minor gastrointestinal symptoms, increased urination, and mild allergic reactions. ² However, severe allergic reactions have occurred occasionally, some of them life threatening. ³ In Australia, one survey found that 20% of allergy-prone individuals were allergic to echinacea.

Other concerns relate to echinacea’s possible immune-stimulating properties. Immunity is a two-edged sword that the body keeps under careful control; excessively strong immune reactions can be dangerous. Based on this concern, echinacea should be used only with caution (if at all) by individuals with autoimmune disorders, such as multiple sclerosis, lupus, and rheumatoid arthritis.

Furthermore, a recent case report strongly suggests that use of echinacea can trigger episodes of erythema nodosum (EN). ⁴ EN is an inflammatory condition that involves tender nodules under the skin. These nodules often arise after cold-like symptoms. In this report, a 41-year-old man took echinacea on four separate occasions when he thought he was developing a cold, and each time he developed EN instead. When he stopped using echinacea for this purpose, he remained free of EN outbreaks for a full year of follow-up. The cause of EN is not known, but it involves increased activity of certain immune cells; echinacea has been observed to cause similar effects in the same immune cells, suggesting that the relationship is not coincidental.

One study raised questions about possible antifertility effects of echinacea. ⁵ When high concentrations of echinacea were placed in a test tube with hamster sperm and ova, the sperm were less able to penetrate the ova. However, since we have no idea whether this much echinacea can actually come in contact with sperm and ova when they are in the body rather than a test tube, these results may not be meaningful in real life.

Animal studies of echinacea are supportive of safety in pregnancy. ⁶ One human study found a bit of evidence that use of echinacea during pregnancy does not increase risk of birth defects, but this evidence is not strong enough to absolutely rely on. ⁷ Furthermore, studies dating back to the 1950s suggest that echinacea is safe in children. ⁸ Nonetheless, the safety of echinacea in young children or pregnant or nursing women cannot be regarded as established. In addition, safety in those with severe liver or kidney disease has also not been established.

Two studies suggest that echinacea might interact with various medications by affecting their metabolism in the liver, but the significance of these largely theoretical findings remain unclear. ⁹ A review of the research literature found no verifiable reports of drug-herb interactions with any echinacea product. ¹⁰