Echinacea is commonly used to treat or prevent colds, flu, and infections, and for wound healing. More than 25 published studies looked at how well Echinacea worked to prevent or shorten the course of a cold, but none were conclusive. A 2014 study compared Echinacea with a placebo for treating colds. Results found that Echinacea did not have any effect on a cold. Other studies have also shown that long-term use can affect the body’s immune system. It should not be used with medicines that can cause liver problems. People allergic to plants in the daisy family may be more likely to have an allergic reaction to Echinacea. The daisy family includes ragweed, chrysanthemums, marigolds, and daisies.