Respiratory tract infections
Supplements studied for respiratory tract infections.
Overview
Echinacea (13 studies) is the most researched supplement for respiratory tract infections. Trials suggest it may slightly lower infection risk and antibiotic use, though results are mixed across products and dosing strategies. Regular use over several months appears more consistent for prevention than high-dose treatment at symptom onset.
Alpha-Linolenic Acid (1 study) and Beta-Glucan (1 study, in combination products) have very limited preliminary data. See the heatmap and evidence reviews below.
Effect graph
Relevant supplements
Relevant supplements sorted by DEX Score.
| Echinacea | ★★★★★ | Low |
| Beta-Glucan | ★★★★★ | Low |
| Alpha-Linolenic Acid | ★★★★★ | Low |
| Lutein | ★★★★★ | Very Low / None |
Studies
Find individual evidence reviews for supplements sorted by DEX Score.
4 supplements for and rated at least stars. All purchase bands. No minimum star filter.
EchinaceaView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Echinacea might slightly lower the chance of getting respiratory infections like colds and reduce the need for antibiotics.
- One large study found that taking higher doses at the start of symptoms helped clear viruses faster but did not shorten how long people stayed sick compared to using a lower dose to prevent illness.
- Many studies show echinacea taken regularly for a few months may help prevent respiratory infections.
- Because the research is very mixed and uses different products and methods, it’s hard to be sure how well it works.
- Currently, the evidence shows that echinacea may slightly help in preventing colds but might not be very helpful once you are sick.
Browse 13 studies·2 meta-analyses
MetaEfficacy and safety of Echinacea purpurea in treating upper respiratory infections and complications of otitis media in children: Systematic review and meta-analysis2025n=1,651
A meta-analysis of 9 pediatric RCTs (1,651 placebo, 1,518 treatment) found E. purpurea reduced URTI duration (SMD −0.19), incidence (RR 0.81), and antibiotic use (RR 0.18), and lowered otitis media episodes (RR 0.56), with mildly increased adverse events.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 1,651
ObservationalEchinacea Reduces Antibiotics by Preventing Respiratory Infections: A Meta-Analysis (ERA-PRIMA)2024n=5,652
A meta-analysis of 30 trials (5,652 subjects) found echinacea reduced monthly RTI occurrence (RR 0.68), complications (RR 0.44), and antibiotic use (RR 0.60), with similar adverse event rates to control.
- Effect
- Benefit
- Population
- Healthy adults
- Participants
- 5,652
RCTEvaluating the Efficacy and Safety of EZC Pak, a 5-Day Combination Echinacea-Zinc-Vitamin C Dose Pack with or without Vitamin D, in the Management of Outpatient Upper Respiratory Infections2024n=360
In 360 outpatients with URIs, EZC Pak (echinacea-zinc-vitamin C) shortened illness by 1.39 days (p = 0.017) and reduced symptom severity by 17.4% (p = 0.029) versus placebo; adding vitamin D did not add benefit.
- Effect
- Benefit
- Duration
- 5 days
- Population
- RA patients
- Participants
- 360
- Ages
- 18+
RCTTherapeutic Potential of a Natural Blend of Aronia melancarpa, Lonicera caerulea, and Echinacea purpurea Extracts in Treating Upper Respiratory Tract Infections: Preliminary Clinical and In Vitro Immunomodulatory Insights2024n=61
In 61 URTI-prone adults over 60 days, an ELA blend (echinacea, Lonicera, Aronia) reduced URTI episodes (2 vs 8; p = 0.044) and throat symptoms (8 vs 16; p = 0.038) versus placebo, with in vitro antiviral and immunomodulatory effects.
- Effect
- Benefit
- Duration
- 60 days
- Population
- RA patients
- Participants
- 61
- Ages
- 18–70
RCTNovel Echinacea formulations for the treatment of acute respiratory tract infections in adults-A randomized blinded controlled trial2023n=409
In 246 adults with acute RTI, high-dose novel echinacea formulations (16,800 mg/day days 1–3) achieved faster viral clearance than conventional 2,400 mg/day doses, with a trend toward faster clinical recovery by day 10.
- Effect
- Benefit
- Duration
- up to 10 days
- Dose
- 16800 mg/day
- Population
- Healthy adults
- Participants
- 409
- Avg age
- ~32
RCTEchinacea Purpurea For the Long-Term Prevention of Viral Respiratory Tract Infections During Covid-19 Pandemic: A Randomized, Open, Controlled, Exploratory Clinical Study2022n=120
In 120 healthy adults over ~6 months, daily 2,400 mg E. purpurea reduced any viral RTI (RR 0.68) and SARS-CoV-2 positivity (RR 0.37, p = 0.03) versus control, with fewer fever days during acute treatment.
- Effect
- Benefit
- Dose
- 2400 mg/day
- Population
- Healthy adults
- Participants
- 120
- Ages
- 18–75
RCTRandomised, double blind, placebo-controlled trial of echinacea supplementation in air travellers2011n=175
In 175 long-haul air travelers, echinacea (standardized to 4.4 mg alkylamides) borderline significantly reduced respiratory symptom scores during travel (P = 0.05) versus placebo.
- Effect
- Benefit
- Duration
- 1–5 weeks
- Dose
- 4.4 mg/day
- Population
- Adults
- Participants
- 175
- Ages
- 18–65
RCTEffects of echinacea on the frequency of upper respiratory tract symptoms: a randomized, double-blind, placebo-controlled trial2008n=90
In 58 hospital workers over 8 weeks, E. purpurea 6 capsules/day did not significantly reduce sick days (9 vs 14 days per person) compared with parsley placebo (p = 0.67).
- Effect
- No Benefit
- Duration
- 8 weeks
- Dose
- 6 capsules/day
- Population
- Women
- Participants
- 90
- Ages
- 18–65
RCTEchinacea purpurea and mucosal immunity2007n=32
In 32 subjects over 4 weeks, echinacea attenuated exercise-induced salivary IgA suppression and shortened reported URTI duration (3.4 vs 8.6 days) versus placebo, without reducing URTI incidence.
- Effect
- Benefit
- Duration
- 4 weeks
- Participants
- 32
RCTEfficacy and safety of echinacea in treating upper respiratory tract infections in children: a randomized controlled trial2003n=407
In 407 children (ages 2–11) with URIs over 4 months, E. purpurea did not reduce URI duration (9 days both groups) or severity, and was associated with increased rash (7.1% vs 2.7%, P = 0.008).
- Effect
- No Benefit
- Duration
- 4 months
- Population
- Children/adolescents
- Participants
- 407
- Ages
- 2–11
RCTA randomized controlled trial of the effect of fluid extract of Echinacea purpurea on the incidence and severity of colds and respiratory infections1999n=109
In 108 adults with frequent colds over 8 weeks, E. purpurea fluid extract (8 mL twice daily) did not significantly reduce cold incidence (65% vs 74%), duration (4.5 vs 6.5 days), or severity versus placebo.
- Effect
- No Benefit
- Duration
- 8 weeks
- Dose
- 4 mL twice/day
- Population
- Healthy adults
- Participants
- 109
RCTEchinacea root extracts for the prevention of upper respiratory tract infections: a double-blind, placebo-controlled randomized trial1998n=18
In 302 healthy adults over 12 weeks, echinacea root extracts did not significantly delay time to first URTI (66–69 vs 65 days) or reduce infection rate (~29–32% vs 37% placebo), though subjects perceived greater benefit.
- Effect
- No Benefit
- Duration
- 12 weeks
- Population
- Healthy adults
- Participants
- 18
RCTPlacebo-controlled, double-blind study of Echinaceae pallidae radix in upper respiratory tract infections1997
A 1997 placebo-controlled, double-blind trial of Echinaceae pallidae radix for upper respiratory tract infections; outcome details were not available in the indexed abstract.
Alpha-Linolenic AcidView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- In children, taking alpha-linolenic acid with linoleic acid during the winter might help lower the number of repeated respiratory infections.
- More studies are needed to confirm this benefit.
Browse 1 study
RCTEssential fatty acids: the effects of dietary supplementation among children with recurrent respiratory infections1996n=20
Cross-over RCT in 20 children with recurrent respiratory infections given 596 mg linoleic plus 855 mg ALA daily found fewer infections, fever days, and school absences during supplementation.
- Effect
- Benefit
- Duration
- 2 winter seasons
- Dose
- 596 mg/day
- Population
- Children/adolescents
- Participants
- 20
- Ages
- 36–49 months
Beta-GlucanView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is uncertain if beta-glucans alone help respiratory infections.
- One early study in young children found a supplement with beta-glucans, elderberry, zinc, and vitamin D3 shortened infections by about 2 days and slightly improved symptoms according to parents.
- It did not reduce how often infections happened, medicine use, or missed school days.
Browse 1 study
RCTPrimary care experience on Stimunex® gocce in children with recurrent respiratory infections: a real-world study during the COVID-19 pandemic era2022n=160
In 298 children with recurrent respiratory infections, 4 months of Stimunex (Sambucus, beta-glucan, zinc, vitamin D) versus standard care reduced infection number and duration and was well tolerated during the COVID-19 pandemic.
- Effect
- Benefit
- Duration
- 4 months
- Population
- Children/adolescents
- Participants
- 160
LuteinView supplement →
Do not purchase·★★★★★
How we scored this▸
- Certain nutrients in the blood, called carotenoids, may support immune health.
- In this study, researchers looked at six main carotenoids in 652 older adults in the Netherlands.
- On average, participants reported about 1.6 respiratory infections over the year.
- Older adults with higher levels of beta-carotene in their blood had fewer infections compared with those with low levels.
- However, beta-carotene and other carotenoids did not affect how severe the illnesses were.
- This suggests that maintaining higher beta-carotene levels may help reduce the risk of catching respiratory infections in older age.
Browse 1 study
RCTPlasma carotenoid concentrations in relation to acute respiratory infections in elderly people2004n=652
In 652 elderly adults, those in the highest beta-carotene quartile had 29% lower acute respiratory infection incidence (IRR 0.71) versus the lowest quartile; lutein/zeaxanthin showed no association.
- Effect
- No Benefit
- Population
- Older adults
- Participants
- 652
- Ages
- 60+
Evidence visualised
Same ratings as above, aggregated so you can see coverage and imbalance.
| Supplement | DEX | Studies | Meta-analyses | Share |
|---|---|---|---|---|
| Echinacea | ★★★★★56% | 13 | 2 | 81% |
| Alpha-Linolenic Acid | ★★★★★44% | 1 | 0 | 6% |
| Beta-Glucan | ★★★★★44% | 1 | 0 | 6% |
| Lutein | ★★★★★32% | 1 | 0 | 6% |