Condition

Acute Respiratory Infection (ARI)

Acute respiratory infections, such as colds, flu and bronchitis, are mostly viral infections of the nose, throat and airways, where the immune response brings on inflammation, extra mucus and cough. The evidence is strongest for zinc, where a large review of trials found a lower risk of these infections, and moderate for Pelargonium sidoides, where bronchitis symptoms eased. The Pelargonium studies were small, though, and vitamin C showed no clear difference in infection risk.

Sources: PMID 34728441; PMID 18222667

Updated 30 September 2026
How we grade
2 studies cited
Acute Respiratory Infection (ARI) protocol

Supplements studied: 11
Medicines and peptides: 1
Graded outcomes: 12
Trials: 7
People studied: 26,573

Evidence by supplement

Strong
Moderate
Limited
Very limited

11 supplements

Zinc

Zinc: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People
	Acute Respiratory Tract Infection Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect	1 study	5,446 people
Studies that measured acute respiratory tract infection risk Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trialsBMJ Open · PMID 34728441
	Acute Respiratory Tract Infection Symptoms	Improves (the measure goes down)			5,446 people
	Common Cold Risk	Changes; see studies			5,446 people

Umckaloabo

Umckaloabo: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People
	Bronchitis Symptoms Moderate Improvement	Improves (the measure goes down)	Moderate effect	4 studies	341 people
Studies that measured bronchitis symptoms Pelargonium sidoides for acute bronchitis: a systematic review and meta-analysisPhytomedicine · PMID 18222667 Treatment of acute bronchitis with EPs 7630: randomized, controlled trial in children and adolescentsPediatr Int · PMID 22360575 Effects of Pelargonium sidoides extract EPs 7630 on acute cough and quality of life - a meta-analysis of randomized, placebo-controlled trials.Multidiscip Respir Med · PMID 36051888 and 1 more on the Umckaloabo page
	Common Cold Symptoms	Improves (the measure goes down)		1 study	1,771 people
Studies that measured common cold symptoms Treatment of signs and symptoms of the common cold using EPs 7630 - results of a meta-analysis.Heliyon · PMID 31844762
	Nasal Congestion	Improves (the measure goes up)		1 study	1,771 people
Studies that measured nasal congestion Treatment of acute rhinosinusitis with the preparation from Pelargonium sidoides EPs 7630: a randomized, double-blind, placebo-controlled trialRhinology · PMID 19382496
	Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		1 study	990 people
Studies that measured upper respiratory tract infection symptoms Herbal Medicine in Children With Respiratory Tract Infection: Systematic Review and Meta-Analysis.Acad Pediatr · PMID 28610802

Vitamin D

Asthma Symptoms: improves
Upper Respiratory Tract Infection Risk: changes; see studies
COPD Symptoms: improves

Vitamin D: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People
	Asthma Symptoms Small Improvement	Improves (the measure goes down)	Small effect	2 studies	11,321 people
Studies that measured asthma symptoms Association between prenatal vitamin D supplementation and respiratory diseases in children: a systematic review and meta-analysis.BMC Pediatr · PMID 41204244 Vitamin D supplementation decrease asthma exacerbations in children: a systematic review and meta-analysis of randomized controlled trials.Ann Med · PMID 39421966
	Upper Respiratory Tract Infection Risk	Changes; see studies		13 studies	3,958 people
Studies that measured upper respiratory tract infection risk The effects of prenatal vitamin D supplementation on respiratory and allergy-related outcomes in children: A systematic review and meta-analysis of randomized controlled trials.World Allergy Organ J · PMID 40535465 High-Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long-Term Care Residents: A Randomized Clinical TrialJ Am Geriatr Soc · PMID 27861708 Randomized trial of vitamin D supplementation and risk of acute respiratory infection in MongoliaPediatrics · PMID 22908115 and 10 more on the Vitamin D page
	COPD Symptoms	Improves (the measure goes down)			11,321 people
	Lower Respiratory Tract Infection Risk	Changes; see studies			10,993 people

Rhamnogalacturonan I

Cold Symptom Severity: improves

Rhamnogalacturonan I: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cold Symptom Severity A single RCT (n=146) challenged healthy volunteers with rhinovirus-16 after 8 weeks of carrot-derived RG-I supplementation (0.3 or 1.5 g/day). cRG-I significantly reduced WURSS-21 symptom scores (p<0.001) and improved quality of life measures (p<0.01) compared to placebo, with 0.3 g/day showing the strongest effects.	Improves (the measure goes down)	Moderate effect	1 study	146 people
Studies that measured cold symptom severity Effects of Dietary Supplementation with Carrot-Derived Rhamnogalacturonan-I (cRG-I) on Accelerated Protective Immune Responses and Quality of Life in Healthy Volunteers Challenged with Rhinovirus in a Randomized TrialNutrients · 2022 · PMID 36296939

Vitamin C

Upper Respiratory Tract Infection Risk
Upper Respiratory Tract Infection Symptoms: improves

Vitamin C: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People
	Upper Respiratory Tract Infection Risk No effect		NoneNo effect	5 studies	1,332 people
Studies that measured upper respiratory tract infection risk Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trialBMJ Mil Health · PMID 32139409 The effects of ascorbic acid and flavonoids on the occurrence of symptoms normally associated with the common coldAm J Clin Nutr · PMID 463806 The clinical and biochemical effects of vitamin C supplementation in short-stay hospitalized geriatric patientsInt J Vitam Nutr Res · PMID 6376396 and 2 more on the Vitamin C page
	Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		24 studies	666 people
Studies that measured upper respiratory tract infection symptoms Vitamin C and the common cold: a double-blind trialCan Med Assoc J · PMID 5057006 Ascorbic acid and the common coldLancet · PMID 4113614 Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled surveyAdv Ther · PMID 12201356 and 21 more on the Vitamin C page

Mitoquinone mesylate

SARS-CoV-2 Infection Risk: improves

Mitoquinone mesylate: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	SARS-CoV-2 Infection Risk An exploratory open-label non-randomized pilot trial (Chen et al., 2024) in 80 individuals with high-risk SARS-CoV-2 exposure found 30% infection rate with MitoQ (20 mg/day for 14 days) vs. 75% in matched controls. Supported by preclinical data (Petcherski et al., 2022, preprint) showing nanomolar antiviral potency in cell and mouse models. Non-randomized design limits conclusions.	Improves (the measure goes down)	Moderate effect	4 studies	80 people
Studies that measured sars-cov-2 infection risk Mitoquinone mesylate as post-exposure prophylaxis against SARS-CoV-2 infection in humans: an exploratory single center pragmatic open label non-randomized pilot clinical trial with matched controlsEBioMedicine · 2024 · PMID 38471990 Oral subchronic toxicity study and genetic toxicity evaluation of mitoquinone mesylateJournal of Applied Toxicology · 2024 · PMID 38860421 Mitoquinone mesylate targets SARS-CoV-2 infection in preclinical modelsbioRxiv · 2022 · PMID 35233569 and 1 more on the Mitoquinone mesylate page

Violet Flower

Respiratory Infection Symptoms: improves

Violet Flower: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Respiratory Infection Symptoms A randomized double-blind controlled trial in 108 COVID-19 outpatients found that add-on violet syrup significantly improved cough (P=0.025), myalgia (P=0.036), and headache (P=0.037) over 7 days compared to standard care alone.	Improves (the measure goes down)	Small effect	2 studies	108 people
Studies that measured respiratory infection symptoms Efficacy and safety of add-on Viola odorata L. in the treatment of COVID-19: A randomized double-blind controlled trialJournal of Ethnopharmacology · 2023 · PMID 36535329 Analysis of Almond-Violet Oil by Gas Chromatography (A Traditional Formula)Iranian Journal of Medical Sciences · 2016 · PMID 27840468

Yeast Mannan

Infection Resistance: improves

Yeast Mannan: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Infection Resistance In European sea bass, MOS feeding improved survival following pathogen challenge. A broiler chicken study demonstrated improved responses to Salmonella typhimurium challenge with dietary yeast cell wall components including MOS. Evidence is limited to animal models.	Improves (the measure goes up)	Small effect	2 studies
Studies that measured infection resistance Response of broiler chickens to dietary different yeast cell wall components challenged with Salmonella typhimurium.Veterinary Research Communications · 2025 · PMID 40996575 Immune stimulation and improved infection resistance in European sea bass (Dicentrarchus labrax) fed mannan oligosaccharides.Fish & Shellfish Immunology · 2007 · PMID 17766145

Echinacea

Sleep Quality
Upper Respiratory Tract Infection Risk: changes; see studies

Echinacea: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People
	Sleep Quality No effect		NoneNo effect		143 people
	Upper Respiratory Tract Infection Risk	Changes; see studies		10 studies	143 people
Studies that measured upper respiratory tract infection risk Echinacea for the prevention and treatment of upper respiratory tract infections: A systematic review and meta-analysisComplement Ther Med · PMID 31126553 Echinacea purpurea for prevention of experimental rhinovirus coldsClin Infect Dis · PMID 15156472 Safety and Efficacy Profile of Echinacea purpurea to Prevent Common Cold Episodes: A Randomized, Double-Blind, Placebo-Controlled TrialEvid Based Complement Alternat Med · PMID 23024696 and 7 more on the Echinacea page

Slippery Elm

Sore Throat Symptom Relief: changes; see studies

Slippery Elm: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Sore Throat Symptom Relief No controlled clinical trials specifically evaluate slippery elm for sore throat. The mucilage content provides a plausible mechanical coating/soothing mechanism, and slippery elm is a common ingredient in commercial throat lozenges, but direct clinical evidence is absent. Efficacy is inferred from traditional use and the well-characterized demulcent properties of plant mucilage.	Changes; see studies	Small effect

Elderberry

Upper Respiratory Tract Infection Symptoms: improves

Elderberry: outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Upper Respiratory Tract Infection Symptoms	Improves (the measure goes down)		3 studies	87 people
Studies that measured upper respiratory tract infection symptoms Elderberry Extract Outpatient Influenza Treatment for Emergency Room Patients Ages 5 and Above: a Randomized, Double-Blind, Placebo-Controlled Trial.J Gen Intern Med · PMID 32929634 Elderberry for prevention and treatment of viral respiratory illnesses: a systematic review.BMC Complement Med Ther · PMID 33827515 Black elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: A meta-analysis of randomized, controlled clinical trials.Complement Ther Med · PMID 30670267

Prescription medicines and peptides studied, for context

These are not supplements. Most need a prescription, and some are research compounds with no approved use. They are listed so the supplement evidence above can be read against them.

1 medicine or peptide

Telavancin (Vibativ)

Hospital-Acquired Pneumonia Efficacy
Mortality in Renal Impairment: worsens

Telavancin (Vibativ): outcomes studied for Acute Respiratory Infection (ARI)
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Hospital-Acquired Pneumonia Efficacy ATTAIN-1 & ATTAIN-2 Phase 3: Clinical cure rates comparable to vancomycin for S. aureus HABP/VABP. FDA-approved June 2013 but indicated only when alternative treatments not suitable due to safety concerns.		NoneNo effect	8 studies
	Mortality in Renal Impairment SAFETY CONCERN: FDA black box warning for increased mortality in patients with CrCl <50 mL/min in HABP/VABP trials. Telavancin should only be used when alternatives not suitable. Risk-benefit assessment required.	Worsens (the measure goes up)	Moderate effect	6 studies

Key findings

Acute Respiratory Tract Infection RiskZincImproves (the measure goes down)
Bronchitis SymptomsUmckaloaboImproves (the measure goes down)
Asthma SymptomsVitamin DImproves (the measure goes down)

Safety notes in the studies

An exploratory open-label non-randomized pilot trial (Chen et al., 2024) in 80 individuals with high-risk SARS-CoV-2 exposure found 30% infection rate with MitoQ (20 mg/day for 14 days) vs.
SAFETY CONCERN: FDA black box warning for increased mortality in patients with CrCl <50 mL/min in HABP/VABP trials.
Risk-benefit assessment required.

The Acute Respiratory Infection (ARI) Treatment Support protocol

2 primary supplements · 7 supporting supplements

Zinc Lozenges75–100 mg total daily as lozenges (every 2–3 hours while awake)
Pelargonium sidoides (Umckaloabo)30–60 drops or 20–30 mg extract 3× daily for 7–10 days

See the full protocol

Shop the evidence-backed picks

Fullscript collectionImmune support: evidence-graded picksOpen on Fullscript

The collection holds the supplements we grade A or B for its theme, in third-party tested products where the catalog has them. It opens in our Fullscript store. You can look through it without signing in; Fullscript asks for a free account to order.

Or shop one supplement

The supplements graded A or B for Acute Respiratory Infection (ARI). Each opens third-party tested products for that supplement.

Grade A
Grade B

We earn from purchases made in our Fullscript store, and links to Fullscript, iHerb or Thorne carry our referral, so we may earn a commission at no extra cost to you. Grades come from the research and never change based on what we earn. Full disclosure

Studies cited

2 studies from PubMed

Effect of long-acting garlic tablets "allicor" on the incidence of acute respiratory viral infections in childrenTer Arkh · PMID 12718222
Honey for acute cough in children - a systematic review.Eur J Pediatr · PMID 37355498