Echinacea: Adverse Reactions. Interactions. Pregnancy Use. Practice Points

2010

Dosage Range

GENERAL GUIDE

• Dried herb: 3 g/day of either Echinacea angustifolia or Echinacea purpurea.

• Liquid extract (1:2): 3-6 mL/day of either Echinacea angustifolia or Echinacea purpurea. This dose may be increased to 10-20 mL/day in acute conditions. Treatment is usually started at the first sign of URTI and continued for 7-14 days.

SPECIFIC GUIDE

Echinacea angustifolia dried root: 1-3 g/day.

Echinacea purpurea dried root: 1.5-4.5 g/day.

Echinacea purpurea dried aerial parts: 2.5-6.0 g/day.

Echinacea purpurea expressed juice of fresh plant: 6-9 mL/day.

Echinacea pallida ethanolic extract of root: 2-4 mL/day.

Although controversy still exists over which part of the plant and which particular plant has the strongest pharmacological activity, it appears that the cold-pressed juice of Echinacea purpurea is the most studied preparation for URTIs.

Adverse Reactions

Oral dose forms and topical preparations tend to be well tolerated, although allergic reactions are possible in rare cases (mainly to the aerial parts, in contact dermatitis). One study using Echinacea purpurea in children found that rash occurred in 7.1% of children using echinacea compared with 2.7% with placebo.

There is no clear evidence from basic science or human studies to show that echinacea causes liver toxicity.

Clinical note — Safety of echinacea

The safety of echinacea has come into question in recent years due to two different articles that were poorly described in the press. One was a case report of suspected anaphylaxis reported in the Medical Journal of Australia. On closer inspection, the article describes an atopic woman who had taken nearly a dozen supplements at once, as well as double the recommended dose of a liquid echinacea product, before experiencing symptoms suggestive of anaphylaxis. Successful treatment consisted of oral promethazine and no other intervention. After the event, hypersensitivity was confirmed by skin prick and RAST testing, suggesting that an allergic response did occur.

In 2002, a second report described in detail five allergic reactions to different echinacea preparations and further stated that 51 adverse reaction reports involving echinacea had been made to ADRAC. Unfortunately, this time the media omitted the important fact that these cases were reported over a 21-year period. Once again, a closer look at the article finds approximately half of those reports were of suspected allergic responses and of those, only two could certainly be linked to echinacea use, with 10 classified as probable and 12 as possible. Considering an estimated 200 million doses of echinacea are used by Australians each year, the relative lack of adverse reports is impressive.

Significant Interactions

Controlled studies are not available; therefore, interactions are based on evidence of activity and are largely theoretical and speculative.

IMMUNOSUPPRESSION AGENTS

Theoretically, there may be an antagonistic pharmacodynamic interaction with immunosuppressive medication, but the clinical relevance is unclear. Exercise caution when using immunosuppressive agents and echinacea concurrently.

Contraindications and Precautions

Contra indicated in people with allergies to the Com positae family of plants (e.g. chamomile, ragweed).

Commission E warns against using echinacea in cases of autoimmune disorders, such as multiple sclerosis, SLE and RA, as well as tuberculosis or leukocytosis. This is based on theoretical considerations and has not been tested in controlled trials. In practice, echinacea has been successfully used by herbalists in autoimmune disease without mishap. Duration of use Based on evidence that parenterally administered echinacea reversibly depresses immune parameters, Commission E has recommended that echinacea should not be used for more than 8 weeks. However, in a study in which it was taken orally for up to 6 months, no changes in immune parameters were detected. As such, no conclusive evidence demonstrates that long-term use is detrimental.

Pregnancy Use

Although safety in pregnancy has not been categorically established, results from a prospective study of 206 women who had inadvertently taken echinacea during their pregnancy found that gestational use is not associated with an increased risk for major malformations. Oral use of echinacea is considered safe in pregnancy when used in recommended doses.

Practice Points / Patient Counselling

• Different types of echinacea have demonstrated immunostimulant, anti-inflammatory, antifungal, antiviral and antioxidant activity.

• Overall, clinical studies support the use of echinacea in URTIs, such as bacterial sinusitis, common cold, influenza-like viral infections and streptococcal throat. Current evidence is strongest for supporting its use as acute treatment in URTIs rather than as prophylactic treatment.

• Several uncontrolled clinical studies support the topical use of echinacea to enhance wound healing.

• Echinacea is also used to treat UTI, allergies, acne and abscesses, as adjunctive therapy in cancer, herpes virus infections and candidiasis.

• Although controversy still exists over which part of the plant and which particular plant has the strongest pharmacological activity, it appears that the cold-pressed juice of Echinacea purpurea is the most studied preparation for URTIs.

Answers to Patients’ Frequently Asked Questions

What will this herb do for me?

Echinacea stimulates immune function and may also haveantifungal, antiviral and anti-inflammatory activity. Scientific research generally supports its use as an acute treatment for URTIs in adults. Applied to the skin, it may also enhance wound healing and be useful for chronic wounds. It also has anti-inflammatory actions.

When will it start to work?

As an acute treatment for URTI, it has effects within the first week of treatment.

Are there any safety issues?

Echinacea is well tolerated, although allergic reactions are possible in rare cases.