A meta analysis of the use of Echinacea for upper respiratory tract infections appeared in Pharmacotherapy [20(6):690-697]. The reviewers looked at studies found in the Medline data base. For the most part, the reviewers were critical of the methodology of the studies—they were all flawed in some way. However, they did conclude that some evidence exists to support the proposed benefits of Echinacea for treating and preventing upper respiratory tract infections. Two sample studies follow.
A randomized, double-blind, placebo-controlled study (Eur J Clin Res 1997;9:261-9) evaluated a commercial preparation of the herb of E. purpurea. One hundred twenty subjects with acute upper respiratory tract infection, 60 in the treatment group and 60 in the placebo group participated in the study.
Four ounces of water with 20 drops of E. purpurea solution every 2 hours on the first day (a proprietary blend, known as Echinagard), and the same dose 3 times/day on the next nine days of the study was given to the treatment group. Subjects recorded symptoms in a daily diary at the beginning of the study and on day 10. Only 40% of the Echinacea group developed fully expressed symptoms of a cold compared with 60% in the placebo group. The authors concluded that Echinagard begun at the first sign of an upper respiratory tract infection inhibited progression and resulted in quicker relief of symptoms than placebo.
The first study was criticized because using a questionnaire is too subjective, and there was no examination performed by a physician until after the symptoms had resolved. Also the reviewers found that the dosages were unclear. In the second study, the reviewers point out that it is unclear when the treatment began (was it day one or day three of the cold?). In spite of the shortcomings of these and the other four studies examined, the reviewers see potential in the use of Echinacea for upper respiratory infections.
E. Pallida root (900 mg. of liquid extract per day) or placebo was given to 160 subjects suffering from a cold lasting less than three days (Complement Ther Med 1997;5:40-2). Subjects were included in the study based on a questionnaire of upper respiratory tract infection symptoms. Subjects were evaluated by a physician at the beginning of the study, on day 3-4 of the study and 8-10 days after the study. A distinction was made between bacterial and viral infections using white blood cell counts. The authors determined that an elevated lymphocyte count indicated a viral infection and an elevated neutrophil count indicated a bacterial infection. The group that received the E. pallida root extract had a shorter duration of illness (9.8 compared to 13 days for bacterial infection and 9.1 compared to 13 days for viral infection). The authors also noted that symptom severity was less in the treated group.
Practitioners used to using natural health care already see the value. Echinacea is especially effective when given early—at the first signs of a cold.