Benefit-risk assessment of the squeezed sap of the purple coneflower (Echinacea purpurea) for long-term oral immunostimulation.

A review is presented of the data on the safety of the squeezed sap of Echinacea purpurea used as an oral immunostimulant. All articles in which the presence or absence of adverse events of the extract of the flowering coneflower or its constituents was reported were considered, provided that the dose and route of administration as well as the patient population were defined. Case reports and reports of practical experience with the extract of E. purpurea were not considered in detail. All reported adverse events and unexpected findings were considered, together with the possible relation to treatment. While parenteral administration of the squeezed sap of E. purpurea (Echinacin(®)) may be associated with symptoms of immunostimulation (shivering, fever, muscle weakness), these are not generally observed on oral administration. Adverse events on oral administration for up to 12 weeks are infrequent and consist mainly of unpleasant taste. In healthy adults, Echinacin(®) has little or no effect on lymphocyte responses, but has been reported to cause transient lymphopenia in some patients with infections of various etiologies. This effect is probably due to redistribution of activated T cells. It is concluded that the squeezed sap of E. purpurea, widely used in self-medication, is well-tolerated on long-term oral administration.