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Echinacea purpurea / angustifolia
Reduces cold risk and shortens infection duration — most effective when started at first sign of symptoms.
What the evidence says
Echinacea helped in about half (6/12) of the studies that measured an effect — promising, but not unanimous.
Most evidence is from high-quality meta-analyses and randomised trials published 2005–2025 with a typical study size of 153 participants.
Based on 34 studies · 9 meta-analyses · 14 RCTs · 14,902 total participants
Confidence
HighWhat the studies found
By outcome
Echinacea has an evidence score of 9/10 — very strong evidence based on 34 indexed studies, including 12 meta-analyses. Reduces cold risk and shortens infection duration — most effective when started at first sign of symptoms.
The commonly studied dose of Echinacea is 300-500mg extract 3x daily at first symptoms, OR 2.5ml tincture 3x daily. Research points to an estimated optimal dose around 1500mg, with a minimum effective dose near 600mg. Individual response varies — start low and adjust.
Timing is flexible for Echinacea — consistent daily use matters more than the time of day. Echinacea is most effective when dosed multiple times daily at the first sign of illness.
Aged Garlic Extract
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Spirulina
Likely helpsBlue-green algae with 60-70% complete protein and unique phycocyanin antioxidant — lowers cholesterol, blood pressure, and blood sugar.
Last reviewed May 2026 · evidence from 40 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Echinacea is a flowering plant native to North America that has become the best-selling herbal immune supplement globally. Research shows it can reduce the risk of catching colds and may shorten their duration. Different species (purpurea, angustifolia) and plant parts (root, aerial) have different active compounds. Most effective when started at first sign of symptoms.
Activates immune cells to fight infection
Direct action against respiratory viruses
How Echinacea works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
300-500mg extract 3x daily at first symptoms, OR 2.5ml tincture 3x daily
Loading: High-dose at cold onset: 1000mg immediately, then 500mg every 2-3 hours for 24-48 hours
Can be taken without food
| Form | Type |
|---|---|
| 💊Standardized extract (4% echinacosides or standardized alkylamides) | Recommended |
| 💧Fresh plant tincture | Alternative |
| 💊Dried root/herb | Alternative |
| 💊Combined species products | Alternative |
E. purpurea aerial parts and E. angustifolia root have the most research. Fresh preparations may be more effective than dried.
Minimum: 1 weeks
Optimal: 1 weeks
Cycling: Best used acutely (at cold onset) or for 8 weeks max continuous use. Take breaks between courses.
Note: Most effective when started within 24 hours of symptom onset. Frequency matters more than single dose size.
Based on meta-analyses showing modest SMD of -0.19. Significant heterogeneity between products tested. Evidence stronger for E. purpurea aerial parts preparations.
Reduced risk of catching colds
Reduced cold duration
Use with caution; consult doctor
Short-term use likely safe; consult doctor
May counteract immunosuppression
May affect drug metabolism
Risk of organ rejection, treatment failure
Risk of organ rejection
Reduced steroid effectiveness, immune activation
Reduced effectiveness, possible disease flare
Tip: Take with food
Tip: Discontinue if rash or swelling occurs
Echinacea is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are GI upset, allergic reaction. Use caution if any of these apply to you: Allergy to Asteraceae/daisy family plants; Autoimmune Conditions (contraindicated); Ragweed Allergy - use with caution.
Andrographis
Probably helpsClinically shown to reduce upper respiratory infection severity and duration when taken at first symptoms — also supports liver health.
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