Echinacea
Summary
Echinacea products vary widely by species, plant part and extraction. A Cochrane review of 24 trials (4,631 people) found no clear benefit once a cold had started and, at most, a weak effect on catching colds. A 2015 analysis of six selected trials reported fewer repeat respiratory infections. Allergic reactions, sometimes severe, occur, especially with daisy-family allergies.
Key facts
- Species, plant part and extraction method vary, so trial results are hard to pool[2]
- Only 1 of 7 treatment trials showed shorter colds[2]
- No single prevention comparison was significant; a post hoc pooling suggested a 10–20% relative reduction[2]
- Reactions can be severe; more likely with allergies to ragweed, daisies or sunflowers[1]
- 2 graded human outcomes on this page
- October 11, 2026
How it works
ProposedTrial authors propose immune-modulating, antiviral and anti-inflammatory effects; the active constituents differ between products because species, plant parts and extraction methods vary.[3][2]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Common colds | Mixed | Grade C | Systematic review · n = 4,631 · 2014 Children and adults in 24 double-blind trials (33 comparisons) Form: Various Echinacea mono-preparations · Dose: Varied across trials · Duration: Varied across trials None of 12 prevention comparisons was significant alone (post hoc pooling suggested a 10–20% relative reduction); only 1 of 7 treatment trials shortened colds. | 24554461 (opens PubMed)Source [2] |
| Repeat respiratory infections | Improved | Grade C | Meta-analysis · n = 2,458 · 2015 Generally healthy children and adults in 6 selected high-quality trials Form: Echinacea extracts (ethanolic extracts and pressed juice) · Dose: Varied across trials · Duration: Varied across trials Recurrent respiratory infections were less likely (RR 0.65) and complications such as pneumonia and ear infection were less frequent (RR 0.50). | 25784510 (opens PubMed)Source [3] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| E. purpurea aerial parts (pressed juice or extract) | Varies | No head-to-head human absorption data in the sources cited here. | Digestive upset is the most common side effect; allergic reactions can occur.[1] | Seven trials in the Cochrane review |
| E. angustifolia or pallida root extracts | Varies | No head-to-head human absorption data in the sources cited here. | Allergic reactions can occur, as with other species.[1] | Fewer trials |
Studied doses
Doses studied in human trials ranged from product to product, because species, plant parts and extracts differed; the reviews cited here give no common dose.[2][3]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Drugs metabolised by the liver; immunosuppressants; caffeineNIH fact sheetNCCIH reports mixed evidence on interactions with some liver-metabolised drugs and theoretical reasons to suspect interactions with immunosuppressants or caffeine.[1]
Who should be careful
- Daisy-family allergies
- Allergic reactions, which can be severe, are more likely in people allergic to ragweed, daisies or sunflowers.[1]
- Children
- NCCIH notes concern that allergic reactions could be severe in some children.[1]
- Breastfeeding
- Little is known about safety while breastfeeding.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Frequently asked questions
Does echinacea shorten a cold?
In the Cochrane review only 1 of 7 treatment trials found shorter colds.[2]
Does it lower the chance of catching colds?
Individual prevention trials were not significant; pooled estimates suggest a small reduction, and a 2015 analysis of six selected trials found fewer repeat infections.[2][3]
Why do studies disagree?
Products differ in species, plant part and extraction, so trials tested different things.[2]
Who should be careful?
People with ragweed or daisy-family allergies, because reactions can be severe.[1]
Sources
- [1]Echinacea. National Center for Complementary and Integrative Health (NCCIH), 2024. fact-sheet
- [2]Echinacea for preventing and treating the common cold.. Cochrane Database Syst Rev, 2014. systematic-review
- [3]Echinacea reduces the risk of recurrent respiratory tract infections and complications: a meta-analysis of randomized controlled trials.. Adv Ther, 2015. meta-analysis
What changed
- First draft. Every PMID checked against NCBI E-utilities (title, journal and year taken from the PubMed record) and each evidence row written from its PubMed abstract; self-reviewed in a separate adversarial pass.