Limited evidenceImmunity

Antiviral Herb Formulas

Multi-herb capsules and tinctures marketed for viral season, usually combining echinacea, elderberry, andrographis, olive leaf and garlic. Some single ingredients have modest evidence; the blends themselves have none.

Evidence last reviewed: August 2026

What the science says

The blends as sold Limited evidence
No commercial multi-herb antiviral formula has been tested in a published randomised placebo-controlled trial. Ingredient lists routinely include five to fifteen herbs at doses far below those used in the single-ingredient studies they borrow credibility from.
Echinacea, the most-studied ingredient Limited evidence
A Cochrane review of echinacea for preventing and treating the common cold found no statistically significant reduction in cold incidence and only a possible weak benefit on duration, with substantial variation between preparations. A later meta-analysis in children reported some benefit but with the same product heterogeneity problem.
Elderberry and andrographis Moderate evidence
A meta-analysis of randomised trials of black elderberry found reduced upper respiratory symptom duration, and a systematic review and meta-analysis of Andrographis paniculata found improvement in cough and sore throat compared with placebo or usual care. Both rest on small trials, several industry-funded, and neither result transfers automatically to a blend containing a fraction of the studied dose.

Dosage & safety

Studied doseNo validated dose for blends. For reference, the single-ingredient trials used roughly 15 mL/day of elderberry syrup or 300-600 mg of extract, and 31.5-200 mg/day of andrographolide. Check whether a blend actually delivers comparable amounts.

SafetyEchinacea can cause allergic reactions in people sensitive to the Asteraceae family and is theoretically inadvisable with immunosuppressants. Andrographis commonly causes taste disturbance, nausea and rash, has been linked to rare liver injury and anaphylaxis, and should be avoided in pregnancy. Olive leaf and garlic may lower blood pressure and affect clotting. Multi-herb blends multiply the interaction surface, so review the full label with a pharmacist if you take prescription medication.

Scientific references

Echinacea for preventing and treating the common cold
Karsch-Völk M, Barrett B, Kiefer D — Cochrane Database Syst Rev, 2014
Black elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: A meta-analysis of randomized, controlled clinical trials
Hawkins J, Baker C, Cherry L — Complement Ther Med, 2019
Andrographis paniculata (Chuān Xīn Lián) for symptomatic relief of acute respiratory tract infections in adults and children: A systematic review and meta-analysis
Hu XY, Wu RH, Logue M — PLoS One, 2017

Where to buy

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Andrographis Moderate evidence