Tejal Somvanshi
A nasal spray commonly used for allergies might have an unexpected benefit – protecting against COVID-19 infection. New research shows the over-the-counter antihistamine azelastine reduced COVID-19 infections by about 70% in a clinical trial.
In a study published September 2, 2025, in JAMA Internal Medicine, German researchers from Saarland University found that people using azelastine nasal spray had significantly lower infection rates compared to those using a placebo.
The trial included 450 healthy adults with an average age of 33, most of whom were vaccinated against COVID-19. Participants were randomly assigned to use either azelastine 0.1% nasal spray or a placebo three times daily for 56 days.
The results were striking. Only 2.2% of people in the azelastine group tested positive for COVID-19, compared to 6.7% in the placebo group. Those who did get infected while using azelastine took longer to become infected – about 31 days versus 19 days for the placebo group.
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“This clinical trial is the first to demonstrate a protective effect in a real-world setting,” said Professor Robert Bals, senior author of the study. “Azelastine nasal spray could provide an additional easily accessible prophylactic to complement existing protective measures.”
The spray didn’t just work against COVID-19. It also reduced overall respiratory infections from 22% in the placebo group to 9.3% in the treatment group, with a notable drop in rhinovirus infections, which cause the common cold.
Researchers aren’t entirely sure why azelastine works against these viruses. They suggest it might bind to viruses in the nasal mucosa – the moist lining inside your nose – and prevent them from replicating. Another possibility is that it blocks the ACE2 receptor that COVID-19 uses to enter cells.
Side effects were generally mild and included bitter taste, occasional nosebleeds, and tiredness – issues already known to occur with azelastine.
Medical experts not involved in the research urge caution about overstating the results.
Dr. William Messer from Oregon Health & Science University described the findings as “reasonably convincing” but questioned whether the demanding regimen of three daily sprays would be practical.
“The mask may be more awkward and annoying but might be easier to comply with than remembering a thrice-daily nasal spray day after day,” Messer said.
Dr. Peter Chin-Hong from UCSF Health emphasized that vaccines should remain the primary defense against COVID-19, especially for older adults.
“While promising, I don’t think it’s prime time to recommend this to block transmission,” he noted. “For those 65 and older, I would still continue to recommend vaccines as my number one defense against COVID.”
The availability of azelastine varies by country. In the United States, it’s available over-the-counter as Astepro Allergy in a 0.15% concentration. Australia also offers it over-the-counter, while in the UK it requires a prescription.
The researchers stress that azelastine isn’t a replacement for vaccines but could serve as an additional protective measure during high-risk situations like travel, crowded events, or COVID-19 surges.
The study had limitations. It was conducted at a single center with mostly young, healthy, vaccinated adults. The researchers called for larger, multicenter trials to further explore azelastine’s potential against COVID-19 and other respiratory viruses.As COVID-19 cases rise in many areas, this readily available nasal spray might offer an additional tool to help reduce infection risk, though medical advice should be sought before starting any new treatment regimen.
