- An Augusta University trial found twice-daily nasal irrigation reduced COVID hospitalizations by 8.5 times in high-risk adults over 55.
- A Baylor College double-blind RCT showed hospitalization rates of ~20% in irrigation groups vs. 58.8% in a reference population (P < 0.001).
- Nasal irrigation works by physically flushing virus from the nasal cavity, reducing viral load, and may inhibit the virus's ability to attach to ACE2 receptors.
- All three trials found nasal irrigation to be safe with minimal side effects.
- Researchers emphasize this is a complementary approach — not a replacement for vaccines or antivirals.
When COVID-19 swept the globe, scientists scrambled for every possible tool to fight the virus. While vaccines and antivirals dominated headlines, a small group of researchers asked a deceptively simple question: what if rinsing your nose with salt water actually made a measurable difference?
It sounds almost too simple. But three clinical trials — conducted at Augusta University, Baylor College of Medicine, and Vanderbilt University Medical Center — put nasal irrigation to the test against SARS-CoV-2. The results were striking enough to be published in peer-reviewed journals, and they offer practical lessons that remain relevant today as respiratory viruses continue to circulate.
As a company that makes sinus rinse packets and advocates for daily nasal hygiene, we've followed this research closely. Here's what the science actually found — no hype, just data.
Why Researchers Thought Nasal Irrigation Might Work Against COVID
The hypothesis behind nasal irrigation for COVID wasn't pulled from thin air. It was grounded in well-understood virology and centuries of practice.
SARS-CoV-2 enters the body primarily through the nose and throat. The virus attaches to ACE2 receptors, which are found in abundance in the nasal cavity, mouth, and lungs. Once the virus gains a foothold in the nasal passages, it replicates rapidly — a 2020 study in Nature found that SARS-CoV-2 viral concentrations in the nasopharynx were 1,000 times higher than those seen with the original SARS-CoV virus.
The logic was straightforward: if you can physically flush viral particles out of the nose before they replicate and migrate to the lungs, you might be able to reduce the severity of illness. As Dr. Amy Baxter from Augusta University's Medical College of Georgia put it: "What we say in the emergency room and surgery is the solution to pollution is dilution."
Nasal irrigation also appears to do more than just physically remove virus. Saline solutions may inhibit the virus's ability to perform "furin cleavage" — a process where SARS-CoV-2 essentially cuts itself to better fit into ACE2 receptors. By disrupting this mechanism, salt water may actively interfere with viral attachment.
Additionally, previous research had already shown that nasal irrigation was effective against other coronaviruses that cause the common cold, reducing symptom duration and viral shedding. COVID-19, caused by a related coronavirus, seemed like a natural next target.
Trial #1: Augusta University — 8.5x Fewer Hospitalizations
The first and most widely cited trial was conducted by Drs. Amy Baxter and Richard Schwartz at the Medical College of Georgia at Augusta University. Published in the Ear, Nose & Throat Journal in 2022, this study remains the largest prospective clinical trial of nasal irrigation for COVID-19.
Participants: 79 adults aged 55 and older, enrolled within 24 hours of a positive COVID-19 PCR test.
Period: September 24 – December 21, 2020 (pre-vaccine era).
Protocol: Twice-daily nasal irrigation with isotonic saline (half teaspoon each of salt and baking soda in one cup of distilled or boiled water).
Follow-up: 28 days.
The Results
The findings were dramatic:
- Hospitalization rate: Only 1.3% of participants who irrigated were hospitalized (1 out of 79). By comparison, CDC data from the same period showed a 9.47% hospitalization rate in a demographically similar group.
- Deaths: Zero deaths among irrigation participants, compared to 1.5% mortality in the CDC comparison group.
- Reduction factor: An 8.5-fold reduction in hospitalizations.
- Symptom resolution: 23 of the 29 participants who irrigated consistently twice daily had zero or one symptom remaining at two weeks, compared to only 14 of 33 who were less diligent.
Critically, this was a high-risk population. Participants had a mean BMI of 30.3 (above the obesity threshold of 30), and many had preexisting conditions like hypertension. These are exactly the people most likely to be hospitalized with COVID.
What About Additives?
The study tested two additives — povidone-iodine (the brown surgical antiseptic) and sodium bicarbonate (baking soda) — mixed with saline. Interestingly, neither additive provided additional benefit beyond what plain saline achieved. "It's really just the rinsing and the quantity that matter," Dr. Baxter concluded.
Trial #2: Baylor College of Medicine — A Double-Blind Randomized Controlled Trial
Published in the Journal of Global Health in December 2024, this trial from Baylor College of Medicine and Harris Health System in Houston addressed a key limitation of the Augusta study: it was a properly blinded, randomized controlled trial.
Participants: 58 individuals aged 18–65, randomly allocated to low-saline (2.13g salt per 8 oz water) or high-saline (6g salt per 8 oz water) groups.
Period: August 2020 – July 2022.
Protocol: Gargling and nasal rinsing four times daily for 14 days.
Reference population: 9,398 SARS-CoV-2 positive individuals evaluated at the same institution during the study period.
The Results
- Low-saline hospitalization rate: 18.5%
- High-saline hospitalization rate: 21.4%
- Reference population hospitalization rate: 58.8%
- Difference: Both saline groups had significantly lower hospitalization than the reference population (P < 0.001).
- No significant differences were observed between the low-salt and high-salt groups, suggesting that even modest salt concentrations are effective.
The fact that both low and high saline concentrations worked equally well is an important finding. It suggests that the mechanical act of flushing — not just the salt concentration — is the primary therapeutic mechanism.
Trial #3: Vanderbilt University Medical Center — Testing Viral Load Reduction
In August 2020, Vanderbilt University Medical Center launched a clinical trial (NCT04559035) specifically designed to evaluate whether nasal irrigation could reduce the severity of COVID-19 symptoms and, crucially, whether it could measurably reduce viral load in the nasal passages.
Design: Randomized controlled trial evaluating nasal saline irrigation vs. standard care in COVID-19 positive outpatients.
Goal: Assess impact on symptom severity, duration, and viral load measured via nasopharyngeal swabs.
The Vanderbilt trial built on prior studies showing that nasal saline irrigations could decrease viral shedding in upper respiratory infections. As the investigators noted, "Prior studies have shown that using simple, over-the-counter nasal saline irrigations can decrease viral shedding in upper respiratory infections." Their goal was to determine whether this applied specifically to SARS-CoV-2.
Additionally, a 2022 randomized trial by Pantazopoulos and colleagues published in the Canadian Respiratory Journal demonstrated that nasopharyngeal wash with normal saline significantly decreased SARS-CoV-2 viral load compared to controls. And a 2024 study by de Gabory et al. in the European Archives of Otorhinolaryngology found that seawater nasal washes were associated with shorter symptom durations and reduced viral loads in COVID-19 patients.
Together, these findings support the underlying mechanism: nasal irrigation physically removes virus and may create conditions less favorable for viral replication.
How Nasal Irrigation Fights Respiratory Viruses: The Mechanisms
Understanding why nasal irrigation works against COVID helps explain why it's likely effective against a range of respiratory viruses, including influenza, RSV, and common cold coronaviruses.
A comprehensive 2023 review published in Frontiers in Public Health by Huijghebaert and colleagues identified several mechanisms:
- Physical viral removal: The sheer volume of saline flowing through the nasal passages physically flushes out viral particles, mucus, and inflammatory debris before they can migrate deeper into the respiratory tract.
- Disrupting viral attachment: Saline may interfere with SARS-CoV-2's ability to perform furin cleavage — the molecular process the virus uses to optimize its binding to ACE2 receptors.
- Reducing micro-aspiration: By clearing the nasopharynx, irrigation limits the amount of virus-laden secretions that can be aspirated into the lungs, where COVID causes its most serious damage.
- Enhancing mucociliary clearance: Saline hydrates the nasal mucosa, improving the function of the cilia (tiny hair-like structures) that naturally sweep pathogens out of the airway.
- Chloride-mediated antiviral activity: Research suggests that chloride ions from salt may be converted to hypochlorous acid by nasal epithelial cells, creating a natural antiseptic environment.
These mechanisms aren't specific to COVID-19. They apply to virtually any respiratory virus that enters through the nose, which is why nasal irrigation has shown benefits across multiple types of upper respiratory infections.
Practical Protocol: How to Use Nasal Irrigation During Respiratory Illness
Based on the protocols used in these clinical trials, here's a practical guide for using nasal irrigation when you're sick with COVID or any upper respiratory infection:
Step 1: Start Early
The Augusta University study enrolled participants within 24 hours of a positive test. Early intervention appears to be key — the sooner you begin flushing viral particles, the less time the virus has to replicate and migrate to the lungs.
Step 2: Use Proper Saline Solution
Use pre-measured, pharmaceutical-grade sinus rinse packets like ATO Health sinus rinse packets for consistent, safe concentrations. If mixing your own, use half a teaspoon each of non-iodized salt and baking soda per cup (240 mL) of distilled or previously boiled water.
Step 3: Irrigate Twice Daily (Minimum)
The Augusta trial used twice-daily irrigation; the Baylor trial used four times daily. Twice daily is a reasonable starting point for most people, with more frequent irrigation for those who can tolerate it.
Step 4: Use Adequate Volume
Use at least 120 mL (4 oz) per nostril per session. Volume matters — you need enough saline to thoroughly flush the nasal passages and reach the nasopharynx where viral replication is concentrated.
Step 5: Continue for at Least 14 Days
Both the Augusta and Baylor trials used protocols lasting 14–28 days. Don't stop after a few days just because you feel better — continue the full course to ensure viral clearance.
Step 6: Gargle Too
The Baylor trial included gargling along with nasal rinsing. Since SARS-CoV-2 also replicates in the throat, adding a 30-second saline gargle after nasal irrigation provides additional benefit.
Nasal Irrigation for COVID: What the Research Doesn't Tell Us (Yet)
While the results are encouraging, it's important to acknowledge what we don't yet know:
- Sample sizes were small. The Augusta study had 79 participants; the Baylor study had 58. These are compelling pilot results, but large-scale trials with thousands of participants would provide more definitive evidence.
- Viral variants evolve. These trials were conducted during earlier waves of the pandemic. Whether the same results apply to current and future variants is an open question, though the mechanism (physical removal of virus) should theoretically be variant-agnostic.
- Prevention vs. treatment. These trials studied nasal irrigation after infection. Whether regular preventive irrigation reduces infection risk in the first place has not been rigorously tested for COVID specifically.
- Comparison populations had limitations. Both trials compared against historical or reference populations rather than randomized placebo controls in the case of the overall hospitalization outcomes.
That said, the safety profile of nasal irrigation is excellent, the cost is negligible, and the potential upside — based on the available data — is substantial.
Beyond COVID: Why Daily Nasal Irrigation Makes Sense Year-Round
The COVID studies reinforced something that ear, nose, and throat specialists have known for decades: regular nasal irrigation is one of the most effective, lowest-risk interventions for respiratory health.
Dr. Baxter observed that many of her study participants who adopted nasal irrigation for COVID ended up continuing it long-term: "Many of the people who have been using this now for months have told me their seasonal allergies have gone away, that it really makes a huge difference in any of the things that go through the nose that are annoying."
She also noted that nasal irrigation has been practiced for millennia in Southeast Asia, and that countries like Laos, Vietnam, and Thailand — where nasal rinsing is a normal part of daily hygiene — experienced lower COVID death rates. While many factors contributed to those differences, the observation is consistent with the clinical data.
Whether you're concerned about COVID, seasonal allergies, chronic sinusitis, or simply want to keep your nasal passages healthy, daily irrigation with a quality saline solution like ATO Health sinus rinse packets is one of the simplest additions you can make to your health routine.
For more on the broad benefits of nasal irrigation backed by clinical research, read our article on how a landmark Lancet study showed nasal irrigation cuts cold duration by 2 days.
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Frequently Asked Questions
Can nasal irrigation help prevent COVID-19 infection?
Current clinical trials focused on nasal irrigation after a positive COVID-19 test, not prevention. However, the mechanism of physically flushing viral particles from the nasal cavity suggests potential preventive benefits. Regular nasal irrigation reduces viral load in the upper respiratory tract, which may lower the risk of infection progressing to severe illness. More research on prevention specifically is needed.
What type of saline solution should I use for nasal irrigation during COVID?
Clinical trials used both isotonic (0.9% salt) and hypertonic solutions with similar success. The Augusta University trial used a half teaspoon each of salt and baking soda in one cup of distilled or boiled water. The Baylor College trial found no significant difference between low-salt (2.13g per 8 oz) and high-salt (6g per 8 oz) regimens. Pre-measured pharmaceutical-grade sinus rinse packets ensure consistent, safe concentrations every time.
How often should you do nasal irrigation if you have COVID?
The Augusta University study used twice-daily nasal irrigation and found an 8.5-fold reduction in hospitalizations. The Baylor College study used gargling and nasal rinsing four times daily. Based on the available evidence, twice-daily irrigation is a reasonable starting point, ideally beginning within 24 hours of a positive test result.
Is nasal irrigation safe to do when you have COVID-19?
Yes. Across all three clinical trials reviewed, nasal irrigation was found to be safe with minimal side effects. In the Augusta University study, only 11 of 62 participants reported irrigation-related complaints, and just 4 discontinued use. Always use distilled, sterile, or previously boiled water — never tap water — and use pharmaceutical-grade saline packets for proper concentration.
Does nasal irrigation replace COVID vaccines or antiviral treatments?
No. Nasal irrigation should be viewed as a complementary supportive care measure, not a replacement for vaccines, antivirals like Paxlovid, or professional medical advice. The researchers in all three trials positioned nasal irrigation as an accessible, low-cost adjunct therapy that can be started immediately at home while other treatments are being arranged.