Possible leukopenia associated with long-term use of echinacea.

Americans spend between $3.5 and $5 billion annually on herbal treatments, and nearly 50 million individuals currently report use of botanical supplements. With so many herbal products on the market, it is imperative that physicians thoroughly question patients with regard to supplement use. Physicians must understand the benefits and risks associated with medicinal herbs and counsel patients as to their safety. Echinacea is one such supplement that has gained popularity in recent years. A member of the daisy family—Asteraceae (Compositae)—Echinacea purpurea is believed to have properties that protect against upper respiratory tract infections such as the common cold. In 1998, retail sales of the product worldwide totaled $69,702,144, and in Germany more than 2 million prescriptions for echinacea were filled each year. Animal studies show echinacea affects the immune system by increasing the number of circulating white blood cells, promoting phagocytosis, and stimulating the production of cytokines. Echinacea is also found to improve wound healing by inhibiting tissue and bacterial hyaluronidase; its extracts could potentially inhibit replication of some viruses directly. According to German Commission E monographs, arguably the best compilation of clinical information about herbs, chronic use (longer than 6 to 8 weeks’ duration) is generally discouraged because of reported cases of immune suppression. For this reason echinacea is contraindicated in patients with acquired immunodeficiency syndrome and other disorders in which immune suppression would be detrimental. Because echinacea is an immune stimulant when administered short term both in vivo and in vitro, it is contraindicated in patients with autoimmune disorders, multiple sclerosis, tuberculosis, and those on immunosuppressant therapy. We describe a case in which chronic use of echinacea resulted in an asymptomatic leukopenia. We believe this case might be the first in the English literature to confirm the German Commission E reports that chronic use indeed results in immune suppression.