Echinacea, adverse effects

There are several botanicals that have purported immunostimulating effects. These include Panax ginseng and Echinacea purpurea (74), which have both been used as an immune stimulant. Any potential adverse effect on the pharmacological activity of immunosuppressants has not been reported in patients or evaluated in clinical studies. Given the lack of data, it would be prudent to advise against concurrent intake of these botanicals, and closely monitor changes in efficacy in patients who self-administer these botanicals. 

Flu-like symptoms (eg, fever, shivering, headache, vomiting) have been reported following the intravenous use of Echinacea extracts. Adverse effects with oral commercial formulations are minimal and most often include unpleasant taste, gastrointestinal upset, or central nervous system effects (eg, headache, dizziness). Allergic reactions such as rash, acute asthma, and anaphylaxis have been infrequently reported. 

A retrospective analysis of aU adverse events related to herbal medicines and dietary supplements reported to the California Poison Control System has given data on the risks of the adverse effects of herbal medicines (112). Between January 1997 and June 1998, 918 calls relating to such supplements were received. Exposures resulting in adverse reactions occurred most often at recommended doses. There were 233 adverse events, of which 29% occurred in children. The products most frequently implicated were zinc (38%), Echinacea (8%), witch hazel (6%), and chromium picolinate (6%). Most of the adverse events were not severe and required no treatment hospitalization was required in only three cases. 

Side effects that have been observed with administration of Echinacea are generally mild and uncommon. Infrequent adverse effects include abdominal upset, nausea, unpleasant taste, and dizziness. Rarely seen effects are anaphylaxis, exacerbation of asthma, and angioedema (28). 

Another study of human sperm and oocytes showed that Echinacea at high concentrations had adverse effects on oocytes and suggested that Echinacea damages reproductive cells (39). 

Unfortunately, persistent misconceptions about botanical safety become part of the conventional wisdom about herbs, as the original case reports are repeatedly cited without any acknowledgement of the explicatory letters that follow in subsequent volumes of the journals in which the original reports or letters appeared. In addition to this unfortunate situation, adverse effects of particular herbs have been predicted, in the absence of case reports or even in vitro studies, on the basis of the chemical composition of the herb in question. For instance, Miller (1998) warned about the expected hepatotoxicity of Echinacea spp. based on the occurrence of the pyrrolizidine alkaloids tussilagine and isotussilagine. These compounds are indeed present (at 0.006%) in Echinacea root, but they are nontoxic because they lack the structural features (1,2 unsaturation in the pyrrolizidine ring) mentioned above necessary for hepatic activation into reactive pyrroles. 

Scaglione and Lund [13] tested a combination of Echinacea purpurea root extract, vitamin C, rosemary leaf extract, eucalyptus leaf extract, and fennel seed extract vs. placebo in 32 subjects suffering from a common cold. The duration of the illness (based on the rhinorrhea) was 3.37 1.25 days in the treatment group and 4.37 1.57 days in the placebo group (p < 0.01). Patients in the treatment groups also used a significantly lower number of paper tissues. No adverse effects were observed. 

Some adverse effects have been reported for echinacea. For example, more than 50 cases of allergy were detected in Australia and were linked to the use of echinacea preparations. Symptoms included acute asthma, maculo-papular rash/urticaria, and anaphylaxis. There was evidence of the involvement of an echinacea-binding IgE in ca. 50% of the cases and the possibility of cross-reactivity between echinacea and other environmental allergens was proposed. ... 

In general, herbal remedies, including St. John s wort, echinacea, kava kava, and ginkgo, should be avoided. St John s wort is considered an herbal remedy with some serotonergic reuptake inhibition properties and is purported to be helpful with depression. It is sometimes used concurrently with SSRI medications by patients who assume it is relatively free of adverse side effects. 

Allergic reactions to Echinacea products have been reported see Adverse Events and Side Effects, below). Some authorities have suggested that the reactions may be due to the presence of Echinacea poUen in products, as allergies to pollens in the Asteraceae family are common. Ingestion of products made from the flowering top of Echinacea are thus more likely to result in allergic reactions than products made from the root and leaf (Mills and Bone 2005 Upton and Graff 2004). 

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