Dr. Philp McMillan,  John McMillan

A surprising discovery from German researchers suggests that a common over-the-counter allergy nasal spray could significantly reduce your risk of catching COVID-19 and other respiratory infections. The findings, published in JAMA Internal Medicine, reveal that azelastine nasal spray—a medication millions have used safely for decades to treat hay fever—may offer a new layer of protection against respiratory viruses.

A Familiar Medicine with Unexpected Benefits

Azelastine has been a trusted remedy for seasonal allergies since long before the COVID-19 pandemic. Available without prescription in most pharmacies, this antihistamine nasal spray works by blocking histamine receptors to reduce allergy symptoms like sneezing and runny nose. But recent laboratory studies hinted at something remarkable: azelastine appeared to have antiviral properties, particularly against SARS-CoV-2, the virus that causes COVID-19.

These laboratory findings prompted researchers at Saarland University Medical Center in Germany to investigate whether this readily available medication could actually prevent infections in real-world conditions. What they discovered exceeded expectations.

The Clinical Trial: Testing Prevention in Practice

The research team, led by Professor Robert Bals, conducted a rigorous double-blind, placebo-controlled trial involving 450 healthy volunteers. Participants were randomly divided into two groups: one used azelastine nasal spray three times daily, while the other used an identical-looking placebo spray. Neither the participants nor the researchers knew who received which treatment until the study concluded.

Over a 56-day observation period, participants underwent regular COVID-19 testing twice weekly, with any positive rapid tests confirmed by PCR testing. The researchers also tested for other respiratory viruses when participants developed symptoms.

The results were striking: only 2.2% of participants using azelastine developed confirmed COVID-19 infections, compared to 6.7% in the placebo group—a three-fold difference. This represents a 67% reduction in infection risk, comparable to the protection offered by some vaccines during their peak effectiveness.

Beyond COVID-19: Broader Protection

Perhaps even more intriguing was azelastine’s apparent effectiveness against other respiratory viruses. The study found that rhinovirus infections – a major cause of the common cold – were similarly reduced, affecting only 1.8% of the azelastine group compared to 6.3% of the placebo group. Overall, participants using azelastine experienced fewer total respiratory infections and reported fewer days of illness.

This broad-spectrum protection suggests that azelastine’s antiviral effects aren’t limited to a single pathogen. Laboratory studies have shown activity against various respiratory viruses, including influenza, respiratory syncytial virus (RSV), and other coronaviruses that cause common colds.

How It Works: Multiple Mechanisms of Protection

Scientists believe azelastine works through several mechanisms to prevent viral infections. The medication appears to interfere with the ACE2 receptor, which SARS-CoV-2 uses to enter human cells. It may also inhibit viral proteins essential for replication and modulate immune responses that viruses exploit. For rhinoviruses, azelastine seems to block ICAM-1, a cellular receptor these viruses need for infection.

Because the spray acts directly where respiratory viruses first attack — the nasal passages — it creates a protective barrier right at the entry point. This localized action may explain why a simple nasal spray can provide such meaningful protection.

Safety and Practical Considerations

The safety profile of azelastine in the study was reassuring, consistent with decades of use for allergies. The most common side effects were mild and well-known: a bitter taste (reported by about 9% of users), occasional nosebleeds (6.6%), and mild tiredness (3.1%). Only two participants discontinued the spray due to side effects, and no serious adverse events were linked to the treatment.

The study protocol required three applications daily during normal conditions, increasing to five times daily during high-risk situations like known exposure to infected individuals. While this frequency might seem demanding, the potential benefits could outweigh the inconvenience for many people, especially during surge periods or before high-risk activities like travel or attending large gatherings.

What This Means for You

These findings suggest that azelastine nasal spray could serve as an additional tool in our respiratory infection prevention toolkit, complementing rather than replacing existing measures. For vulnerable populations—elderly individuals, those with chronic conditions, or immunocompromised patients—this could provide an extra layer of protection during high-risk periods.

The medication’s over-the-counter availability, established safety record, and relatively low cost make it an accessible option for many people. However, it’s important to note that this was a single study conducted primarily in healthy, vaccinated individuals. The results need confirmation through larger, more diverse trials before definitive recommendations can be made.

Looking Forward

Professor Bals emphasizes that while these results are promising, further research is essential. Larger multicenter trials are needed to confirm these findings across different populations and settings. Researchers also want to explore optimal dosing schedules, duration of protection, and effectiveness against emerging viral variants.

The discovery that a simple allergy nasal spray might help prevent COVID-19 and other respiratory infections represents the kind of unexpected breakthrough that can emerge from careful scientific investigation. As we continue to navigate a world where respiratory viruses pose ongoing challenges, having multiple prevention strategies—especially ones that are safe, accessible, and already familiar to millions—could prove invaluable.

While we await further confirmation through additional studies, this research offers hope that protection against respiratory infections might be as close as your local pharmacy’s allergy medication aisle. For those seeking additional protection during high-risk periods, discussing azelastine nasal spray with a healthcare provider might be worth considering, particularly given its long history of safe use and newly discovered potential benefits.

Azelastine Nasal Spray for Prevention of SARS-CoV-2 Infections: A Phase 2 Randomized Clinical Trial