Echinacea - Drug Monograph

Introduction

Echinacea is a popular herbal supplement derived from several species of the Echinacea plant, primarily Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida. Traditionally used by Native Americans for various medicinal purposes, echinacea has gained widespread popularity as an immune system booster and remedy for upper respiratory infections. Unlike conventional pharmaceuticals, echinacea is regulated as a dietary supplement in the United States under the Dietary Supplement Health and Education Act (DSHEA) of 1994.

Mechanism of Action

The exact mechanism of action of echinacea remains incompletely understood, but several immunomodulatory effects have been proposed based on preclinical studies:

• Immunostimulatory effects: Alkylamides and polysaccharides in echinacea may stimulate phagocytosis, enhance leukocyte mobility, and promote cytokine production
• Anti-inflammatory properties: Inhibition of cyclooxygenase and 5-lipoxygenase enzymes may contribute to anti-inflammatory effects
• Antiviral activity: Some constituents may interfere with viral replication and penetration
• Antioxidant effects: Contains compounds that scavenge free radicals

The pharmacological activity varies significantly among different echinacea species, plant parts (aerial vs. root), and preparation methods.

Indications

• Prevention and treatment of the common cold
• Symptomatic relief of upper respiratory tract infections
• Support for immune system function

• Topical application for wound healing
• Support for urinary tract health
• Management of anxiety (limited evidence)

Dosage and Administration

Dosing varies considerably based on formulation, species, and plant part used:

• Dried root: 1-2 g three times daily
• Tincture (1:5): 2-3 mL three times daily
• Expressed juice: 6-9 mL daily
• Standardized extracts: Follow manufacturer instructions

• For acute infections: Begin at first sign of symptoms and continue for 7-10 days
• For prevention: Cycling regimens (e.g., 2 weeks on, 2 weeks off) are often recommended
• Take with food to minimize gastrointestinal discomfort

• Pediatric use: Limited safety data; some formulations not recommended under 12 years
• Geriatric use: No specific dosage adjustments recommended
• Renal/hepatic impairment: No specific guidelines available

Pharmacokinetics

The pharmacokinetic profile varies significantly based on the specific preparation and constituents.

Contraindications

• Known hypersensitivity to Echinacea species or other plants in the Asteraceae/Compositae family (ragweed, chrysanthemums, marigolds)
• Autoimmune diseases (multiple sclerosis, lupus, rheumatoid arthritis, etc.)
• Tuberculosis
• Leukosis
• Collagen disorders
• HIV/AIDS
• Organ transplantation recipients

Warnings and Precautions

• Allergic reactions: May cause anaphylaxis in sensitive individuals, particularly those with Asteraceae allergies
• Autoimmune disorders: May theoretically stimulate immune function and exacerbate conditions
• Pregnancy: Avoid use due to potential hormonal effects and lack of safety data
• Lactation: Avoid use due to lack of safety data
• Hepatic function: Monitor with prolonged use; case reports of hepatotoxicity
• Duration of use: Limited data on long-term safety; generally recommended for short-term use only

Drug Interactions

• Immunosuppressants (cyclosporine, tacrolimus, corticosteroids): May reduce efficacy
• Caffeine: Echinacea may inhibit CYP1A2, increasing caffeine levels
• Midazolam: May inhibit CYP3A4, increasing sedative effects

• Antiretroviral drugs: Theoretical concern for reduced efficacy
• Chemotherapeutic agents: Theoretical concern for interference with treatment
• Substrates of CYP1A2, 2C9, 2C19, 2D6, 3A4: May alter metabolism of numerous medications

Adverse Effects

• Unpleasant taste
• Gastrointestinal discomfort
• Nausea
• Dizziness

• Allergic reactions (rash, urticaria, bronchospasm)
• Headache
• Insomnia

• Anaphylaxis
• Hepatitis
• Leukopenia (with prolonged use)
• Asthma exacerbation in sensitive individuals

Monitoring Parameters

• Signs of allergic reactions, especially during initial use
• Liver function tests with prolonged use
• Immune function in patients with underlying immune disorders
• Effectiveness for intended use
• Adverse effects profile

Patient Education

• Echinacea is a dietary supplement, not an FDA-approved medication
• Choose reputable brands that provide standardization information
• Discontinue use and seek medical attention if allergic reactions occur
• Do not use for more than 8-10 weeks continuously
• Inform healthcare providers about all supplement use
• Not recommended for prevention of colds in children
• Store according to manufacturer instructions, typically in cool, dark place

References

1. Barrett BP, Brown RL, Locken K, et al. Treatment of the common cold with unrefined echinacea. A randomized, double-blind, placebo-controlled trial. Ann Intern Med. 2002;137(12):939-946.

2. Shah SA, Sander S, White CM, Rinaldi M, Coleman CI. Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infect Dis. 2007;7(7):473-480.

3. Woelkart K, Bauer R. The role of alkamides as an active principle of echinacea. Planta Med. 2007;73(7):615-623.

4. National Center for Complementary and Integrative Health. Echinacea. https://www.nccih.nih.gov/health/echinacea. Updated 2020.

5. Barnes J, Anderson LA, Gibbons S, Phillipson JD. Echinacea species (Echinacea angustifolia (DC.) Hell., Echinacea pallida (Nutt.) Nutt., Echinacea purpurea (L.) Moench): a review of their chemistry, pharmacology and clinical properties. J Pharm Pharmacol. 2005;57(8):929-954.

6. Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Austin, TX: American Botanical Council; 2000.

7. Gurley BJ, Fifer EK, Gardner Z. Pharmacokinetic herb-drug interactions (part 2): drug interactions involving popular botanical dietary supplements and their clinical relevance. Planta Med. 2012;78(13):1490-1514.