Reviewed by the Scan Dose Research Team and Clinical Advisory Board
Echinacea
MODERATE EVIDENCEBotanicalLast updated April 2026
SCAN DOSE SUMMARY
Echinacea is one of the most popular herbal supplements for immune support, but our research shows the evidence is frustratingly inconsistent. Some trials show modest cold duration reduction (12-24 hours shorter), others show nothing. Species matters (E. purpurea vs E. angustifolia), plant part matters (aerial parts vs root), and extract type matters. Overall verdict: possibly helpful if started at first symptoms, unlikely to prevent colds.
EVIDENCE GRADES
Common cold duration (treatment)Inconsistent — Cochrane review mixed (PMID: 24554461)
C+
Common cold preventionWeak — most prevention trials negative
Immune cell activationIn vitro and ex vivo data strong
B-
Anxiety (E. angustifolia)Very preliminary
C
WHAT IT DOES
Echinacea contains alkamides, caffeic acid derivatives (cichoric acid, echinacoside), and polysaccharides. Alkamides modulate immune function via CB2 cannabinoid receptors and TNF-α. Different species and plant parts contain different active compound profiles:
E. purpurea aerial parts: Most studied for cold treatment. Rich in alkamides and cichoric acid.
E. purpurea root: Different compound profile; less commonly studied.
E. angustifolia root: Rich in echinacoside; studied for anxiety.
E. pallida root: Used in German phytomedicine.
OPTIMAL DOSAGE
Cold treatment (E. purpurea): 2,400mg/day extract or 4,000-6,000mg dried herb, started within 24 hours of symptoms, for 7-10 days
Prevention: 2,400mg/day for 4 months (evidence weak)
Echinaforce (branded): 4,000mg/day at onset (PMID: 25784510)
Duration: Do not take continuously for >8 weeks — efficacy may decrease