Common Cold

The common cold is andrographis’s flagship indication. Meta-analyses of RCTs find it (alone or combined with Eleutherococcus) shortens and eases the common cold and acute URTI — about a 10.85-point symptom-score advantage over placebo in one pooled analysis, improved cough and sore throat across a 33-RCT synthesis (7,175 patients), and a cough-specific SMD of −1.00 ^{1,2,3,4Reference 1Coon et al. · 2004Systematic reviewAndrographis paniculata in the treatment of upper respiratory tract infections: a systematic review of safety and efficacy — systematic reviewView study →Reference 2Poolsup et al. · 2004Meta-analysisAndrographis paniculata in the symptomatic treatment of uncomplicated upper respiratory tract infection: systematic review of randomized controlled trials — meta-analysisView study →Reference 3Hu et al. · 2017Meta-analysisAndrographis paniculata for symptomatic relief of acute respiratory tract infections in adults and children: a systematic review and meta-analysis — systematic reviewView study →Reference 4Wagner et al. · 2015Meta-analysisHerbal medicine for cough: a systematic review and meta-analysis — meta-analysisView study →}, with a throat-spray RCT adding topical support ^{5Reference 5Okonogi et al. · 2023RCTEfficacy of Andrographis paniculata spray in acute pharyngitis: a randomized controlled trial — RCTView study →}.

Many pivotal trials tested the fixed Kan Jang combination rather than the herb alone, standardisation varies, and all data are for extracts titrated to andrographolide — not a bitter tea.

A systematic review and meta-analysis found ginseng reduced seasonal URTI incidence (RR 0.69) and, for P. quinquefolius specifically, ~25% fewer colds and roughly 6 days shorter duration, with RCTs of the proprietary CVT-E002/COLD-fX polysaccharide extract cutting respiratory illness in seniors and vaccinated adults ^{24,25,26,27Reference 24Antonelli et al. · 2020Meta-analysisGinseng integrative supplementation for seasonal acute upper respiratory infections: a systematic review and meta-analysis — meta-analysis, systematic reviewView study →Reference 25Seida et al. · 2011Systematic reviewNorth American (Panax quinquefolius) and Asian Ginseng preparations for prevention of the common cold in healthy adults: a systematic review — systematic reviewView study →Reference 26McElhaney et al. · 2006RCTEfficacy of COLD-fX (CVT-E002) in the prevention of respiratory symptoms in community-dwelling adults: a randomized, double-blinded, placebo-controlled trial — randomised controlled trialView study →Reference 27McElhaney et al. · 2011RCTEfficacy and Safety of CVT-E002 in the Prevention of Respiratory Infections in Influenza-Vaccinated Community-Dwelling Adults: a multicenter, randomized, double-blind, placebo-controlled trial — randomised controlled trialView study →}. Prevention, not treatment — the trials carry high-to-unclear risk of bias, the active article is a specific polysaccharide extract (not the root), and the most rigorous trial missed its primary endpoints ^{24,28Reference 24Antonelli et al. · 2020Meta-analysisGinseng integrative supplementation for seasonal acute upper respiratory infections: a systematic review and meta-analysis — meta-analysis, systematic reviewView study →Reference 28High et al. · 2012RCTA randomized, controlled trial of Panax quinquefolius extract (CVT-E002) to reduce respiratory infection in patients with chronic lymphocytic leukemia — randomised controlled trialView study →}.

The best Asian-ginseng immune trial gave the standardised G115 extract (100 mg/day for 12 weeks) as an influenza-vaccine adjuvant, and combined influenza and common-cold cases fell to 15 in the ginseng group versus 42 on placebo, with higher antibody titres ^{29Reference 29Scaglione et al. · 1996RCTEfficacy and safety of the standardised ginseng extract G115 for potentiating influenza vaccination — randomised placebo-controlled trialView study →}. The evidence for prevention rests on this single vaccination-adjuvant trial — most of the wider ‘ginseng prevents colds’ evidence is actually for American ginseng, not the Asian species ^{30Reference 30Predy et al. · 2005RCTEfficacy of a North American ginseng extract for preventing upper respiratory tract infections — randomised controlled trialView study →}.

Echinacea’s best-supported use is prevention, not treatment: pooled analyses show a modest reduction in the odds of catching a cold (2007 meta-analysis OR 0.42; 2019 review RR 0.78), and in children a standardised E. purpurea extract cut URTI incidence and antibiotic use ^{6,7,8,9Reference 6Shah SA et al. · 2007Meta-analysisEvaluation of echinacea for the prevention and treatment of the common cold — meta-analysisView study →Reference 7David S · 2019Meta-analysisEchinacea for the prevention and treatment of upper respiratory tract infections — systematic review and meta-analysisView study →Reference 8Ogal M et al. · 2021RCTEchinacea reduces antibiotic usage in children through respiratory tract infection prevention — randomized controlled trialView study →Reference 9Pham TP et al. · 2025Meta-analysisEfficacy and safety of Echinacea purpurea in treating upper respiratory infections and otitis media in children — systematic review and meta-analysisView study →}. Cochrane, however, found none of 24 individual prevention trials significant on its own, so the effect is small and product-specific ^{10Reference 10Karsch-Völk M et al. · 2014Systematic reviewEchinacea for preventing and treating the common cold — systematic review (Cochrane)View study →}.

Evidence that it shortens an already-established cold is weak and largely null ^{10,11,12Reference 10Karsch-Völk M et al. · 2014Systematic reviewEchinacea for preventing and treating the common cold — systematic review (Cochrane)View study →Reference 11Barrett B et al. · 2010RCTEchinacea for treating the common cold — randomized controlled trialView study →Reference 12Taylor JA et al. · 2003RCTEfficacy and safety of echinacea in treating upper respiratory tract infections in children — randomized controlled trialView study →}. Effects belong to specific pressed-juice and alcoholic aerial E. purpurea extracts, not tea or a different species/part.

A standardised membrane-filtered berry extract produced significantly shorter, milder colds in a 312-person air-traveller RCT (though it did not reduce the number of episodes), and a 2019 meta-analysis of four RCTs found a large pooled reduction in upper-respiratory symptoms ^{13,14Reference 13Tiralongo et al. · 2016RCTElderberry supplementation reduces cold duration and symptoms in air-travellers: a randomised, double-blind placebo-controlled clinical trial — RCTView study →Reference 14Hawkins et al. · 2019Meta-analysisBlack elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: a meta-analysis of randomized, controlled clinical trials — meta-analysisView study →}.

The evidence is contested: trials are small with overlapping authorship/products, the single most rigorous influenza RCT was null ^{15Reference 15Macknin et al. · 2020RCTElderberry extract outpatient influenza treatment for emergency room patients ages 5 and above: a randomized, double-blind, placebo-controlled trial — RCTView study →}, and benefit is tied to standardised heat-processed berry extracts, not home syrups or raw fruit.

Standardised 1,8-cineole capsules relieve the congestion of acute viral (non-purulent) rhinosinusitis significantly faster than placebo in two double-blind RCTs and rank well in a network meta-analysis, and cineole is an established secretolytic that thins mucus and raises mucociliary clearance ^{18,19,20,21Reference 18Kehrl et al. · 2004RCTTherapy for acute nonpurulent rhinosinusitis with cineole: results of a double-blind, randomised, placebo-controlled trial — RCTView study →Reference 19Tesche et al. · 2008RCTThe value of herbal medicines in the treatment of acute non-purulent rhinosinusitis — randomised controlled trialView study →Reference 20Hoang et al. · 2023Meta-analysisHerbal medicines for rhinosinusitis: a systematic review and network meta-analysisView study →Reference 21Hasani et al. · 2003RCTEffect of aromatics on lung mucociliary clearance in patients with chronic airways obstruction — randomised clinical trialView study →}.

The benefit is symptom relief only, and the clinical data are all for the isolated oral cineole capsule: the steam inhalation most people reach for has essentially no controlled efficacy data, and neat eucalyptus oil is acutely toxic if swallowed.

Thyme-containing syrups shorten acute cough in upper-respiratory infection: a 2015 systematic review and meta-analysis of four ivy/primrose/thyme trials found clear benefit for cough resolution (relative ratio 1.40, 95% CI 1.23–1.60), anchored by two large placebo-controlled bronchitis RCTs ^{4,31,32Reference 4Wagner et al. · 2015Meta-analysisHerbal medicine for cough: a systematic review and meta-analysis — meta-analysisView study →Reference 31Kemmerich · 2007RCTEvaluation of efficacy and tolerability of a fixed combination of dry extracts of thyme herb and primrose root in adults with acute bronchitis — double-blind, placebo-controlled, randomised multicentre trialView study →Reference 32Kemmerich et al. · 2006RCTEfficacy and tolerability of a fluid extract combination of thyme herb and ivy leaves vs placebo in acute bronchitis — randomised, double-blind, placebo-controlled trialView study →}. This is symptom relief (cough) rather than a cure, and the evidence is specifically for fixed thyme combinations (thyme + ivy, thyme + primrose) — no comparably powered trial tests a thyme monopreparation.

Ephedra’s alkaloid pseudoephedrine is a proven oral decongestant — α-adrenergic vasoconstriction of nasal mucosa, with extensive human support as a standalone drug and in cold combination products ^{16,17Reference 16Ibragic et al. · 2015ReviewChemical composition of various Ephedra species — reviewView study →Reference 17Corren et al. · 1997RCTEfficacy and safety of loratadine plus pseudoephedrine in patients with seasonal allergic rhinitis and mild asthma — randomised controlled trialView study →} — the basis for the herb’s traditional use in congested ‘wind-cold’ colds.

The clean evidence is for the isolated, dose-controlled alkaloid: the crude stem delivers a variable 0.5–2.5% alkaloid load, and ephedra carries real cardiovascular and CNS risk and is banned or regulated as a supplement in several jurisdictions — not for self-directed use.

The claim that garlic prevents colds rests essentially on one 2001 double-blind RCT (n=146) in which a 12-week allicin supplement produced fewer colds (24 vs 65) and faster recovery ^{22Reference 22Josling P · 2001RCTPreventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey — randomized controlled trialView study →}. The 2014 Cochrane review identified this as the only trial meeting its criteria and concluded there is insufficient evidence to judge garlic’s effect on the common cold ^{23Reference 23Lissiman E et al. · 2014Systematic reviewGarlic for the common cold — systematic reviewView study →} — a single small study with subjective self-reported endpoints, unreplicated, and dependent on fresh/allicin-yielding preparations rather than aged or cooked garlic.