COVID-19 treatment: respiratory tract administration

• Direct treatment to the primary source of initial infection reduces progression and transmission

Over 10,000 compounds predicted to reduce risk—SARS-CoV-2 easily disabled SARS-CoV-2 infection involves a complex interplay of over 400 host and viral proteins and other factors1-117, providing many therapeutic targets. Scientists have identified 10,976+ compounds118 potentially beneficial for COVID-19. Hundreds of compounds inhibit SARS-CoV-2 in vitro, including many with known pharmacokinetics and proven safety.
Primary entry via the upper respiratory tract Studies point to the upper respiratory tract, and specifically the nasal respiratory epithelium as the primary source of infection and initial replication50,119-121(a). The primary initial route for entry into the central nervous system is thought to be the olfactory nerve in the nasal cavity123-127.
Efficacy confidence - naso/oropharyngeal
p < 0.00000001
p < 0.00000001
p < 0.00000001
p < 0.00000001
p = 0.0002
p = 0.003
p = 0.003 (exc. late)
p = 0.008
p = 0.018
p = 0.024
p = 0.048
P-values indicate the confidence that studies show a significant effect. p = 0.05 is the typical threshold for significance, with lower values indicating higher confidence. See the individual analyses for details of efficacy for specific outcomes and conditions.
Naso/oropharyngeal treatment is effective Many compounds with existing safety records are expected to be beneficial within the upper respiratory tract. 89 clinical studies (65 RCTs) show lower risk for early treatment or prophylaxis with povidone-iodine, alkalinization, nitric oxide, iota-carrageenan, phthalocyanine, hydrogen peroxide, chlorhexidine, NaCl, CPC, chlorpheniramine, azelastine, and inhaled heparin128-224, confirmed in multiple additional meta-analyses225-228. Targeted administration to the respiratory tract has several advantages:
Direct treatment to the primary source of initial infection.
Rapid onset of action.
Higher local drug concentrations.
Reduced systemic side effects.
Naso/oropharyngeal treatments may be effective via many mechanisms, e.g.: inactivating virions, blocking attachment/entry, creating a physical barrier, mechanical clearance, altering the environment to hinder fusion/replication, inhibiting spike-priming proteases, enhancing mucociliary function, and priming local innate immunity(b).
Studies use various administration methods including nasal/oral sprays, rinses, and inhalation. Combined nasal/oral application shows the highest efficacy. Efficacy depends on administration details, e.g., viscosity, mucoadhesion, sprayability, droplet size229,230, dispersion229, and the angle of administration for sprays230. Some treatments may disrupt beneficial microbial populations, requiring care to avoid side effects and suggesting a preference for more selective treatments, especially with longer-term use(c).
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Respiratory tract administration efficacy
Oral application38% [25‑49%]
Nasal application59% [50‑66%]
Nasal & oral88% [72‑95%]
Meta-analysis for early treatment/prophylaxis.
Only 4% of studies applied treatment directly to the primary location of initial infection.
Only 4% of studies we cover used direct naso/oropharyngeal treatment, despite the strong potential and advantages. With focused research, safe, inexpensive, and effective naso/oropharyngeal treatments may be rapidly identified for new respiratory pathogens. Many additional compounds may be effective, with promising but limited data to date(d).
Naso/oropharyngeal treatments experience regulatory challenges. For example the US FDA shut down a povidone-iodine treatment257 when 7 RCTs showed efficacy, and the FTC sent warning letters to companies that referenced studies showing benefits of nasal/oral hygiene for COVID-19258-260.
Naso/oropharyngeal treatment reduces transmission Immediate or prophylactic naso/oropharyngeal treatment also logically reduces transmission. A 621-patient RCT showed 92% reduction in transmission with nasal and oropharyngeal sprays containing povidone-iodine and glycyrrhizic acid135. In contrast, the commonly recommended masking shows no significant efficacy in RCTs to date, with 4 COVID-19 RCTs showing 2.2% [-25‑24%] improvement261.
Treatment at the source of initial infection
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Figure 1. Optimal spray angle may increase drug delivery 100x, adapted from230.
Studies show targeted treatment to the upper respiratory tract via nasal/oral sprays, rinses, or inhalation can significantly reduce COVID-19 transmission and progression. Several of these are widely available in most countries, including treatments with povidone-iodine, chlorhexidine, alkalinizing agents, iota-carrageenan, and many more.
In many cases, authorities prevent marketing for COVID-19, despite evidence of efficacy. However, treatments specifically marketed for COVID-19 are becoming more widely available including SanoTize262, a nitric oxide generating nasal spray available in 10 countries(e), and NoriZite263, nasal/oral sprays with iota-carrageenan available in the UK.
Nasopharyngeal/oropharyngeal treatments work via different methods. The following tables summarize the primary mechanisms of action, mechanisms for specific treatments, and the potential for disruption to the natural oral and nasal microbiomes.
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Nasal/oral sprays and rinses—primary mechanisms
Primary mechanisms of action for nasopharyngeal/oropharyngeal sprays and rinses. Note: sequenced application is possible to maximize efficacy—for example, using a virucidal spray/wash first (to clean), followed by a barrier spray (to protect), with a 5-10 minute drying window in between.
Virucidal action Chemically inactivating or destroying the structure of viral particles
Blocking attachment Binding to the virus or host cells to prevent viral attachment to host cells
Physical barrier Forming a physical layer over the nasal mucosa preventing viral access to host cells
Physical removal Mechanical washout/flushing of viral particles and mucus (e.g., large volume irrigation)
Mucociliary clearance Stimulating the natural beating of nasal cilia to accelerate the clearing of trapped pathogens
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Nasal/oral sprays and rinses—mechanisms of action
Nasopharyngeal/oropharyngeal treatments have many different mechanisms of action. Specific treatments may have significant systemic effects or significantly alter the microbiome.
Treatment Mechanisms Notes
Azelastine220 Antiviral: inhibits interaction between spike protein and ACE2
Antiviral: potential inhibition of viral protease (Mpro)
Other: H1-receptor antagonist (antihistamine)
Other: mast cell stabilizer
Antihistamine. Designed to affect human receptors. Risks include dysgeusia, drowsiness, and nasal burning.
Cetylpyridinium Chloride211 Virucidal: disrupts viral lipid envelope
Antiseptic: quaternary ammonium compound
Chemical virucide. Common in mouthwashes. Can cause temporary staining of teeth or tongue irritation if used frequently.
Chlorhexidine198 Virucidal: disrupts viral lipid membranes
Antiseptic: cationic polybiguanide
Chemical virucide. May cause tooth staining and altered taste.
Chlorpheniramine215 Antiviral: binds to viral spike protein to block entry
Antiviral: high affinity for viral transport proteins
Other: H1-receptor antagonist (1st generation antihistamine)
Other: anticholinergic activity
Antihistamine. Stronger systemic risks than azelastine. Known to cause significant sedation/drowsiness and cognitive impairment.
Hydrogen Peroxide194 Virucidal: oxidizing agent that destroys viral parts
Other: tissue debridement
Chemical virucide. Can be toxic to healthy tissue if concentration is too high (>1%). Long-term safety on nasal mucosa is debated.
Inhaled Heparin224 Antiviral: acts as a decoy receptor (mimics heparan sulfate)
Antiviral: anti-inflammatory effects on lung tissue
Other: Anticoagulant
Anticoagulant. Use requires caution regarding bleeding risks.
Iota-carrageenan180 Barrier: forms a viscous physical layer on mucosa
Trap: electrostatistically traps virus particles (mimics cell surface)
Physical barrier. High safety profile for daily use.
NaCl208 Cleaning: physically washes away viral particles
Support: moisturizes mucosa to support natural immune barrier
Physical wash. High degree of safety, reduces viral load via physical removal.
Nitric Oxide178 Virucidal: physically damages viral structure via nitrosylation
Other: vasodilator (relaxes blood vessels) in systemic use
Virucide/drug hybrid. In nasal spray form, it acts primarily as a topical disinfectant. Rapidly cleared, so systemic vasodilation risks are low but present.
Phthalocyanine185 Virucidal: generates reactive oxygen species (ROS) when exposed to light to kill virus
Other: photosensitizer
Chemical virucide. A synthetic compound often used in photodynamic therapy. Works by creating an oxidative environment hostile to the virus.
Povidone-Iodine150 Virucidal: oxidizes viral proteins and destabilizes membrane structures
Antiseptic: broad-spectrum bacterial/fungal killer
Chemical virucide. Highly effective but risk of thyroid absorption with chronic use. Can be irritating to mucous membranes.
Sodium Bicarbonate264 Environment: raises pH to inhibit viral fusion
Cleaning: improves mucociliary clearance (washing)
Physical/chemical environment. Changes the environment rather than attacking the virus directly. High degree of safety.
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Nasal/oral sprays and rinses may affect the microbiome
Nasopharyngeal/oropharyngeal treatments may significantly alter the microbiome. These effects may be more important with longer-term prophylaxis.
Treatment Microbiome disruption potential Notes
Iota-carrageenan180 Low Primarily antiviral, however extended use may mildly affect the microbiome
Nitric Oxide178 Low to moderate More selective towards pathogens, however excessive concentrations or prolonged use may disrupt the balance of bacteria
Alkalinization165 Moderate Increases pH, negatively impacting beneficial microbes that thrive in a slightly acidic environment
Cetylpyridinium Chloride211 Moderate Quaternary ammonium broad-spectrum antiseptic that can disrupt beneficial and harmful bacteria
Phthalocyanine185 Moderate to high Photodynamic compound with antimicrobial activity, likely to affect the microbiome
Chlorhexidine198 High Potent antiseptic with broad activity, significantly disrupts the microbiome
Hydrogen Peroxide194 High Strong oxidizer, harming both beneficial and harmful microbes
Povidone-Iodine150 High Potent broad-spectrum antiseptic harmful to beneficial microbes
Protocols combine multiple treatments No single treatment is guaranteed to be effective and safe for a specific individual. Leading evidence-based protocols combine multiple treatments.
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Combined treatments increase efficacy
Monotherapy29% [26‑32%]
Polytherapy69% [57‑78%]
Meta-analysis of early treatment studies.
Complementary/synergistic actions, viral evolution, escape risk suggest polytherapy There are many complementary mechanisms of action, and studies show complementary and synergistic effects with polytherapy268-284. For example, Jitobaom et al.269 shows >10x reduction in IC50 with ivermectin and niclosamide, an RCT by Said et al.276 showed the combination of nigella sativa and vitamin D was more effective than either alone, and an RCT by Wannigama et al.285 showed improved results with fluvoxamine combined with additional treatments, compared to fluvoxamine alone.
SARS-CoV-2 can rapidly acquire mutations altering infectivity, disease severity, and drug resistance even without selective pressure286-293. Antigenic drift can undermine more variant-specific treatments like monoclonal antibodies and more specific antivirals. Treatment with targeted antivirals may select for escape mutations294. The efficacy of treatments varies depending on cell type295 due to differences in viral receptor expression, drug distribution and metabolism, and cell-specific mechanisms. Efficacy may also vary based on genetic variants296-306.
Variable efficacy across variants, cell types, tissues, and host genetics, along with the complementary and synergistic actions of different treatments, all point to greater efficacy with polytherapy. In many studies, the standard of care given to all patients includes other treatments—efficacy seen in these trials may rely in part on synergistic effects. Less variant specific treatments and polytherapy targeting multiple viral and host proteins may be more effective. Meta-analysis of all early treatment trials shows 69% [57‑78%] lower risk for studies using combined treatments, compared to 29% [26‑32%] for single treatments.
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Combined treatment is more effective
SARS-CoV-2 involves the complex interplay of 400+ host and viral proteins and factors, providing many therapeutic targets. Many compounds have antiviral activity for SARS-CoV-2, with many different mechanisms including blocking attachment, entry, and replication. Combinations of treatments, with careful attention to potential side effects, allows improved efficacy via complementary and synergistic mechanisms.
Tissue and cell coverage Different compounds have different tissue penetration profiles and efficacy across cell types
Variant coverage Compounds with different viral resistance profiles
Intra/extracellular Disabling and removing intracellular and extracellular viral particles
Resistance Minimizing persistence and emergence of resistant variants
Genetics Robustness against individual variations in efficacy based on genetics
Lower doses Potentially lower doses of individual agents, reducing toxicity
Viral and host-directed Antivirals targeting viral and host proteins
Immune system function Supporting or enhancing natural immune system function
Disease phases Addressing multiple disease phases (viral replication, inflammation, secondary complications)
Contact.
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Funding.
We have received no funding or compensation in any form, and do not accept donations. This is entirely volunteer work.
Conflicts of interest.
We have no conflicts of interest. We have no affiliation with any pharmaceutical companies, supplement companies, governments, political parties, or advocacy organizations.
AI.
We use AI models (Gemini, Grok, Claude, and ChatGPT) tasked with functioning as additional peer-reviewers to check for errors, suggest improvements, and review spelling and grammar. Any corrections are verified and applied manually. Our preference for em dashes is independent of AI.
Dedication.
This work is dedicated to those who risked their career to save lives under extreme censorship and persecution from authorities and media that have not even reviewed most of the science. In alphabetical order, those that paid the ultimate price: Dr. Thomas J. Borody, Dr. Jackie Stone, Dr. Vladimir (Zev) Zelenko; and those that continue to risk their careers to save lives: Dr. Mary Talley Bowden, Dr. Flavio Cadegiani, Dr. Shankara Chetty, Dr. Ryan Cole, Dr. George Fareed, Dr. Sabine Hazan, Dr. Pierre Kory, Dr. Tess Lawrie, Dr. Robert Malone, Dr. Paul Marik, Dr. Peter McCullough, Dr. Didier Raoult, Dr. Harvey Risch, Dr. Brian Tyson, Dr. Joseph Varon, and the estimated over one million physicians worldwide that prescribed one or more low-cost COVID-19 treatments known to reduce risk, contrary to authority beliefs.
Public domain.
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Entry via the eyes and gastrointestinal tract is possible, but less common122, and entry via other routes is rare.
Nasal/oral sprays, rinses, etc. may be effective via multiple mechanisms: directly inactivating virions: e.g., oxidizers, antiseptics, and cationic surfactants may disrupt the viral envelope or proteins; blocking attachment/entry: e.g., sulfated/negatively charged polymers can bind spike or its heparan-sulfate co-receptor to prevent docking; creating a physical barrier on the mucosa: e.g., mucoadhesive cellulose/carrageenan or dendrimer polymers form a coating that traps particles and limits spread across the epithelium; mechanically removing viral particles: e.g., saline irrigation/gargling may physically remove virus-laden mucus and reduce viral load; altering the local environment to be less favorable for viral fusion/replication: e.g., altering the pH/osmolarity/ionic strength; inhibiting host proteases needed for spike priming: e.g., topical protease inhibitors can reduce entry activation; providing antimicrobial nitric oxide (NO): e.g., NO-releasing nasal sprays provide direct antiviral activity; enhancing mucociliary function: e.g., improving ciliary beat frequency and mucus transport, aiding in viral expulsion; and priming local innate immunity: e.g., intranasal interferon-α may induce an antiviral state in nasal epithelium.
Chlorhexidine, PVP-I, and hydrogen peroxide are broad-spectrum agents that do not discriminate between beneficial and harmful microbes—excessive use may significantly disrupt the microbiome. Cetylpyridinium chloride, a quaternary ammonium antiseptic, is less disruptive but may still alter microbial balance. Nitric oxide primarily attacks respiratory pathogens but high concentrations may also damage some commensal bacteria. Iota-carrageenan and alkalinization are expected to have more minimal impact on the natural microbiome.
Many additional compounds may be effective with nasopharyngeal/oropharyngeal treatment, with promising but limited clinical data to date, including astodrimer sodium231-234, benzalkonium chloride235, CDCM236,237, dequalinium chloride235, hypochlorous acid236, hexadecyl pyridinium chloride238, ethyl lauroyl arginate239, Sinomarin162, PCANS240, SA58241-244, ColdZyme245, Panthexyl246, HH-120247,248, TriSb92249, IBIO123250, homoharringtonine251, A8G6252,253, STI-9167254, FSY-ACE2-NVs nanoSpray255, and Sentinox256.
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