Echinacea for the prevention and treatment of upper respiratory infections

Echinacea products are widely used to treat and prevent colds and other infections. Three randomized, placebo-controlled trials found no benefit of echinacea-only products in preventing upper respiratory infections (URIs). However, six of seven randomized, placebo-controlled trials did a benefit for several extracts echinacea in treating URIs— E. pallida root, E. purpurea root, and E. purpurea pressed juice (NOTE: trials of E. purpurea root found no effect). Echinacea extracts contain alkylamides, caffeic acid derivatives, ketoalkenes/ketoalkynes glycoproteins, and polysaccharides; it is unknown which compounds are most active. Echinacea products have been associated with allergic skin reactions, asthma, urticaria/angioedema, and anaphylaxis.