About the research on this page. The studies cited here investigate photobiomodulation (PBM) as a therapeutic modality and the specific wavelengths used in PBM research — not Mito Red Light devices. The wavelengths in our panels were chosen because the peer-reviewed PBM literature supports them. Evidence levels and study counts reflect the broader research base, not studies of our products. See the full methodology note at the bottom of this page.

Red Light Therapy for Immunity & Infections: Clinical Evidence & Research

304 StudiesPhotobiomodulation (PBM) Source-linked

What the research shows

Our evidence rating: Low for COVID-19 and cold sores; trials are small with high risk of biasUpdated Reviewed by Alexis Cowan, PhD

Most infection research on light therapy comes from COVID-19 and cold sores. In a randomized trial in people with COVID-19, a home-use device shortened recovery for those treated within 7 days of symptoms (18 versus 21 days, p = 0.050), with no benefit for later starters (Lim 2024). For loss of smell after COVID-19, infrared light added to steroids and smell training improved smell test scores (Oliveira 2025). For cold sores (herpes labialis), 6 trials found less pain, faster healing by about 1.2 days and smaller lesions than conventional treatment, though risk of bias was high (Yang 2025).

Other results are null or early. A 2026 double-blind trial in post-COVID brain fog found no significant improvement in the main cognitive score, and mobility and fatigue favored sham (Lim 2026). Overall evidence for COVID-19 treatment remains limited (de Matos 2021).

Based on 304 indexed studies in this category, 41 of them in people. These studies test photobiomodulation in general, not Mito Red Light devices.

Evidence by condition

Number of studies in our database for each condition. Direction and certainty are shown only where a meta-analysis or systematic review reports them; otherwise the row says "not graded".

ConditionHuman randomized trialsAll human studiesDirection of resultsCertainty
COVID-19 8 19 Faster recovery only with early treatment
Lim 2024 (PMID 38940733)
Not graded (single trial)
COVID-19: post-covid symptoms 4 6 Better smell scores; brain fog not improved
Oliveira 2025 (PMID 40147122); Lim 2026 (PMID 41768981)
Not graded (small trials)
Infections 0 4 Not graded Not graded

Key studies: Immunity & Infections

The strongest human evidence: systematic reviews and meta-analyses first, then the newest randomized trials. Each card comes straight from our study database and links to the paper.

Systematic review

Photobiomodulation Therapy as a Possible New Approach in COVID-19: A Systematic Review

et al., Life (Basel), 2021. PMID 34207199

Key finding (checked against the abstract)Systematic review of light therapy in COVID-19: case reports, case series and one trial. Possible benefits, but the authors describe a large evidence gap.
RCT

Photobiomodulation Treatment with a Home-Use Device for COVID-19: A Randomized Controlled Trial for Efficacy and Safety

et al., Photobiomodul Photomed Laser Surg, 2024. PMID 38940733

Key finding (checked against the abstract)Randomized trial in people with COVID-19. With 0-7 days of symptoms, home light treatment shortened median recovery to 18 versus 21 days (p = 0.050); no benefit with 8-12 days of symptoms.
Population
Human: 199 participants; randomized trial; 35-day treatment
RCT

Efficacy of the adjunctive use of photobiomodulation therapy in olfactory disorders in post-COVID-19 patients: A randomized controlled trial

et al., Braz J Otorhinolaryngol, 2025. PMID 40147122

Key finding (checked against the abstract)Randomized trial, post-COVID loss of smell. Infrared light plus steroids and smell training improved smell scores (+4.6 points) versus control.
Population
Human: 81 participants; randomized trial, sham-controlled
Wavelength
660+780nm
Dose
140 J/cm²
RCT

Photobiomodulation for cognitive dysfunction (Brain Fog) in post-COVID-19 condition: a randomized double-blind sham-controlled pilot trial

et al., EClinicalMedicine, 2026. PMID 41768981

Key finding (checked against the abstract)Double-blind randomized trial, 43 people with post-COVID brain fog. No significant difference in the main cognitive score (p = 0.088); mobility and fatigue favored sham.
Population
Human: 43 participants; randomized trial, double-blind; 8-week treatment -> 4-week follow-up
Wavelength
810nm
Systematic review

Photobiomodulation in the management of persistent olfactory and gustatory dysfunction post-COVID-19: a systematic review

et al., Lasers Med Sci, 2025. PMID 40522371

Key finding (checked against the abstract)10 studies of post-COVID loss of smell and taste. Red and infrared light were associated with recovery, but most studies were small or uncontrolled.
Meta-analysis

Comparison of photobiomodulation therapy with conventional treatment in patients with herpes labialis: a systematic review and meta-analysis of randomized controlled trials

et al., Lasers Med Sci, 2025. PMID 40993440

Key finding (checked against the abstract)6 randomized trials, 260 people with cold sores. Less pain, faster healing (1.2 days) and smaller lesions than conventional treatment; high risk of bias.
Population
Human

Studies that found no effect

Not every trial is positive. "No effect" means the main outcome did not differ from sham or control. "Mixed" means some outcomes improved but the outcome named here did not differ.

YearStudyDesignResultOutcome with no difference
2025 Effects of intravenous laser irradiation on viral load and T lymphocytes in people living with HIV/AIDS RCT, n = 28 No effect Outcomes in people with HIV
2024 Photobiomodulation Treatment with a Home-Use Device for COVID-19: A Randomized Controlled Trial for Efficacy and Safety RCT, n = 199 Mixed Recovery when started after 7 days of symptoms (earlier start helped)

Latest human studies: Immunity & Infections

The 25 most recent human studies in our database for this category.

YearStudyDesignPopulation
2026 Management of oral Pseudomonas aeruginosa infections in oncology patients using antimicrobial photodynamic therapy, photobiomodulation, and systemic antibiotics: a case series. Human study Human
2026 Clarithromycin-based therapy with adjunctive photobiomodulation and microwave treatment for cutaneous Mycobacterium marinum infection Human study, n = 14 Human: 14 patients; retrospective study
2026 Photobiomodulation for cognitive dysfunction (Brain Fog) in post-COVID-19 condition: a randomized double-blind sham-controlled pilot trial RCT, n = 43 Human: 43 participants; randomized trial, double-blind; 8-week treatment -> 4-week follow-up
2025 Oral Manifestations of Pediatric Multisystem Inflammatory Syndrome. Case report Human
2025 Effects of intravenous laser irradiation on viral load and T lymphocytes in people living with HIV/AIDS RCT, n = 28 Human: 28 participants; randomized trial, sham-controlled
2025 A Randomized Placebo-Controlled Clinical Trial of Vascular Photobiomodulation in Hospitalized Patients With Sepsis RCT, n = 30 Human: 30 participants; randomized trial
2025 Treatment of neuropathic pain in leprosy patients with a physiotherapeutic protocol combined with photobiomodulation RCT, n = 30 Human: 30 participants; randomized trial, double-blind
2025 Pulsed Blue Light and Phage Therapy: A Novel Synergistic Bactericide. Human study Human
2025 Efficacy of the adjunctive use of photobiomodulation therapy in olfactory disorders in post-COVID-19 patients: A randomized controlled trial RCT, n = 81 Human: 81 participants; randomized trial, sham-controlled
2025 Adjuvant Effect of Photobiomodulation in the Pain Relief and Healing of Ulcerative Lesions from Mammary Tuberculosis Human study Human: case report
2025 Impact of Intravenous Laser Irradiation of Blood on Cognitive Function and Molecular Pathways in Long COVID Patients: A Pilot Study Single-arm study, n = 6 Human: 6 participants; single-arm study; 8 weeks
2024 Unravelling the Complexity of Mucormycosis-A Rare Case Report. Case report Human
2024 Photobiomodulation Treatment with a Home-Use Device for COVID-19: A Randomized Controlled Trial for Efficacy and Safety RCT, n = 199 Human: 199 participants; randomized trial; 35-day treatment
2023 Application of a physiotherapeutic protocol associated with photobiomodulation for the treatment of leprosy patients RCT, n = 30 Human: 30 participants; randomized trial; 4 weeks
2023 Management of Oral Lesions in Chikungunya Virus Disease Using Photobiomodulation Therapy: A Therapy Worth Exploring Human study Human: case report
2023 Photobiomodulation, Transmucosal Laser Irradiation of Blood, or B complex as alternatives to treat Covid-19 Related Long-Term Taste Impairment: double-blind randomized clinical trial RCT, n = 50 Human: 50 participants (39 completed); randomized trial, double-blind; 1 month
2023 Effects of Photobiomodulation Therapy on Lung Function and Inflammatory Factors in Patients with COVID-19 During Acute Stage RCT, n = 30 Human: 30 participants; randomized trial, double-blind; 5 days
2023 Diode laser in management of loss of taste sensation in patients with post-COVID syndrome: a randomized clinical trial RCT, n = 36 Human: 36 participants; randomized trial, sham-controlled; 1 month
2023 Use of either Transcranial or Whole-Body Photobiomodulation Treatments improves COVID-19 Brain Fog Human study, n = 14 Human: 14 participants; comparison study (PBM vs PBM); 4 weeks
2023 Can photobiomodulation restore anosmia and ageusia induced by COVID-19? A pilot clinical study Human study, n = 20 Human: 20 participants; comparison study (PBM vs PBM)
2023 Phototherapies for the management of a large painful facial cutaneous lesion from human monkeypox infection Human study Human: case report
2023 Cardiopulmonary and hematological effects of infrared LED photobiomodulation in the treatment of SARS-COV2 RCT, n = 30 Human: 30 participants; randomized trial, sham-controlled; 7 days
2022 A Novel Approach of Combining Methylene Blue Photodynamic Inactivation, Photobiomodulation and Oral Ingested Methylene Blue in COVID-19 Management: A Pilot Clinical Study with 12-Month Follow-Up Case series, n = 8 Human: 8 participants; case series; ~4 days
2022 Analysis of the Potential of Blood Transvascular Sublingual with Light-Emitting Diode Irradiation in COVID-19 Patients: A Pilot Clinical Study RCT, n = 14 Human: 14 participants; randomized trial, sham-controlled; 7 days
2022 Photobiomodulation Improves Serum Cytokine Response in Mild to Moderate COVID-19: The First Randomized, Double-Blind, Placebo Controlled, Pilot Study RCT, n = 52 Human: 52 participants; randomized trial, double-blind; 3 days

Light parameters used in the trials

Wavelengths reported in our database for the 17 human randomized trials in this category (17 wavelength entries; many database records lack a wavelength, and some trials report more than one). This describes the research; it is not a dosing recommendation.

Wavelength bandTimes used in trials
Red (600-699 nm)7
Near-infrared (800-899 nm)5
Near-infrared (900-1200 nm)4
Blue/green (400-599 nm)1

Most common wavelengths: 660-669 nm, 800-809 nm, 540-549 nm, 620-629 nm, 650-659 nm.

What the evidence does not show

  • Improved post-COVID brain fog: the main cognitive score did not differ significantly from sham (Lim 2026, PMID 41768981).
  • Benefit when COVID-19 treatment starts late: no improvement for people with 8 or more days of symptoms (Lim 2024, PMID 38940733).
  • Established treatment for COVID-19: authors describe a large evidence gap (de Matos 2021, PMID 34207199).

Frequently asked questions

Does red light therapy help cold sores?

Six randomized trials found less pain, about 1.2 days faster healing and smaller lesions than conventional treatment, with high risk of bias (Yang 2025).

Does it help COVID-19?

In one randomized trial, early home use shortened recovery from 21 to 18 days (Lim 2024). Evidence overall is limited (de Matos 2021).

Does it help loss of smell after COVID-19?

Infrared light, combined with steroids and smell training, improved smell test scores in a 2025 randomized trial (Oliveira 2025).

Browse All Immunity & Infections Studies

All 304 studies in this category from our study database, built on the PBM Research Database by Vladimir Heiskanen.

Search every study across all categories: Open the Full Evidence Explorer →

Methodology & important context

The published research indexed and referenced on this page studies photobiomodulation (PBM) as a therapeutic modality and the specific wavelengths used in those studies — not Mito Red Light devices specifically. The wavelengths used across our panels were chosen because the peer-reviewed PBM literature supports them: this is where published evidence is deepest, where dosing parameters have been characterized in human studies, and where clinical guidelines (such as WALT for inflammation and pain) exist. Mito Red Light has not funded or conducted registered clinical trials on our specific devices, and the study counts referenced here reflect the broader PBM research base — not studies of our products.

Where review authors graded certainty (for example with GRADE), we report their grade; other ratings are Mito’s summary. Study counts reflect peer-reviewed photobiomodulation research drawn from major scientific literature databases, peer-reviewed journals, and other published research repositories. PBM response varies meaningfully by person, tissue, condition, dose, wavelength, and session timing; outcomes reported in the published literature may not be replicable for every user. Mito Red Light devices are not intended to diagnose, treat, cure, or prevent any disease. If you have a medical condition or are under a physician’s care, please consult your healthcare provider before beginning any photobiomodulation regimen.