Echinacea purpurea
What it is
One of the most popular herbal cold remedies, but evidence is surprisingly mixed. The Karsch-Völk et al. 2014 Cochrane review (24 trials) found echinacea may slightly reduce cold risk but effect sizes were small and inconsistent across trials; the review was later retired in 2020 without an updated conclusion. The problem is that product formulations vary enormously in species, plant part, and extraction method. Most effective when started at the first sign of symptoms rather than as daily prevention.
Dose
300–500 mg standardised extract × 3 daily at first sign of cold for 7–10 days; evidence inconsistent
Time of day & tips
Take with food or water. Start at first sign of symptoms — do not use for daily prevention. Limit to 7–10 days per course. Avoid with immunosuppressants.
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