Echinacea

• Upper respiratory tract infections (common cold): Meta-analyses and systematic reviews indicate echinacea (especially standardized Echinacea purpurea extracts) may modestly reduce the risk of developing a cold (roughly 10–20% relative reduction) and may shorten duration by about 0.5–1.5 days when started at first symptoms; results are heterogeneous and several well-designed RCTs are negative, so benefits appear small to modest at best (evidence: moderate).
• Symptom severity in acute colds: Some trials report mild improvements in global symptom scores versus placebo, particularly with E. purpurea pressed-juice/aerial-part extracts; findings are inconsistent (evidence: moderate to emerging).
• Recurrent respiratory infections: Some analyses suggest fewer recurrences and related complications with longer-term prophylaxis, but trials vary in quality and may be product-specific (evidence: emerging).
• Antiviral activity: In vitro and small clinical studies suggest activity against common respiratory viruses (e.g., rhinoviruses, influenza, and coronaviruses), but clinical relevance beyond colds prevention/treatment remains uncertain (evidence: emerging).
• Traditional uses: Historically used by Native American and European herbal traditions for wound care and general immune support; modern clinical corroboration for non-respiratory uses is limited (evidence: traditional/emerging).

• Common (1–10%): Gastrointestinal upset (nausea, abdominal pain), diarrhea, headache, dizziness; unpleasant taste and mouth/tongue tingling with liquid extracts.
• Uncommon (0.1–1%): Skin reactions (rash, pruritus, urticaria); transient elevations in liver enzymes.
• Rare (<0.1%): Severe allergic reactions including anaphylaxis, particularly in those with ragweed/Asteraceae allergy or atopy/asthma; serious cutaneous reactions have been reported very rarely. Isolated reports of hepatotoxicity, often confounded by combination products (e.g., echinacea/goldenseal).
• Dose-related: Higher or more frequent dosing is more likely to cause GI discomfort and oral tingling with tinctures/pressed juice.
• Most RCTs report adverse event rates similar to placebo, but allergic reactions can be clinically significant in susceptible individuals.

Not a prescriptive recommendation. Commonly used ranges in studies vary by species, plant part, and standardization:

• Standardized Echinacea purpurea extracts (aerial parts/pressed juice): 900–2,400 mg/day for prevention over up to 8–16 weeks in divided doses; during acute colds, 2,400–4,000 mg/day for 5–10 days in some trials.
• Liquid preparations: pressed-juice or tincture preparations often used at approximately 6–9 mL/day (pressed juice) or about 2–3 mL three times daily (tincture) in acute-use studies.
• Products differ markedly (E. purpurea vs. E. angustifolia vs. E. pallida; aerial vs. root; alkamide/cichoric-acid standardization), so dose equivalence is not assured. Optimal dosing likely depends on preparation and individual response.

• Known allergy to Asteraceae/Compositae family (ragweed, chrysanthemums, daisies) or prior hypersensitivity to echinacea.
• Autoimmune diseases (e.g., multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis), progressive systemic diseases (e.g., tuberculosis), or immunodeficiency states (e.g., HIV/AIDS): theoretical immune-stimulating effects warrant caution; use only with clinician oversight.
• Organ transplant recipients or anyone on immunosuppressive therapy (e.g., calcineurin inhibitors, biologics): avoid due to potential antagonism of therapy.
• Liver disease/hepatitis or concurrent hepatotoxic medications: use cautiously and monitor.
• Pregnancy and breastfeeding: limited and mixed human data (some small observational studies show no major teratogenic signal); safety not well established—avoid or use only if potential benefits outweigh risks after medical consultation.
• Children, especially under 12 years or with atopy/asthma: higher relative risk of allergic reactions noted by some regulators—seek medical advice.
• Pre-surgical: discontinue 1–2 weeks before elective surgery due to possible immunologic effects and mild CYP3A4 modulation.