COVID-19 nasal spray may cut infection risk 69%, cold risk 71%

Show summary Hide summary

• How the trial was run and who took part
• Primary goals and laboratory monitoring
• Key findings: fewer infections with azelastine
• Effect on other respiratory viruses and overall infection burden
• Safety profile and common side effects
• What clinicians recommend and who should be cautious
  • Practical tips for use
  • Safety precautions
• Limitations of the study and next steps

A widely sold allergy nasal spray has shown promising signs of reducing the chance of catching COVID-19 and other respiratory infections in a controlled clinical trial. The research raises questions about whether an over-the-counter remedy might serve as an extra layer of protection in high-risk settings.

How the trial was run and who took part

Researchers at Saarland University Hospital in Germany conducted a phase 2, double-blind, placebo-controlled study from March 2023 to July 2024. Neither participants nor study staff knew who received the active medication.

• 450 healthy adults, ages 18 to 65, enrolled.
• Most had prior COVID-19 vaccination, with a median of three doses.
• Enrollment was public, via universities, pharmacies, and social media.
• Participants reported no acute infections at the start.

People were randomized to receive either azelastine nasal spray (0.1% azelastine hydrochloride) or an identical-appearing placebo. Both sprays contained standard inactive ingredients like hypromellose and saline. The regimen was one spray per nostril three times daily for 56 days.

If someone developed symptoms or had a known exposure, they increased dosing to five sprays per nostril for three days. Testing used trained staff to perform rapid antigen checks twice a week, with PCR confirmation for positives.

Primary goals and laboratory monitoring

The main outcome measured was the number of PCR-confirmed SARS-CoV-2 infections during the 56-day period. Secondary outcomes included symptomatic cases, time to infection, duration of positive tests, and rates of other respiratory viruses.

• Symptom-driven testing used multiplex PCR panels to detect rhinovirus, influenza, RSV, and other coronaviruses.
• Adverse events and serious adverse events were actively tracked throughout the trial.
• Results were published online Sept. 2 in JAMA Internal Medicine.

Key findings: fewer infections with azelastine

Among 227 people given azelastine and 223 on placebo, infection rates differed significantly.

• COVID-19 PCR-positivity: 2.2% with azelastine vs. 6.7% with placebo.
• This is roughly a 69% lower relative risk for those using the active spray in the trial.
• Average time to a positive COVID-19 test was longer with azelastine: 31 days vs. 19 days.
• Duration of positive rapid antigen tests was shorter in the azelastine group: 3.4 days vs. 5.1 days.

These differences indicate not only fewer infections but also delays and shorter detectable viral periods for people who used the active spray.

Effect on other respiratory viruses and overall infection burden

The trial also screened for common cold viruses and flu-like pathogens. Rhinovirus emerged as the most frequent non-COVID pathogen.

• Rhinovirus detection: 1.8% with azelastine vs. 6.3% with placebo.
• This represents an approximate 71% relative reduction.
• Overall lab-confirmed respiratory infections occurred in 8.4% of azelastine users and 18.8% of placebo users.

These numbers suggest the spray may lower the incidence of several respiratory illnesses, not just SARS-CoV-2.

Safety profile and common side effects

Adverse events were generally mild and aligned with known effects of azelastine. No deaths occurred, and serious events were rare and not linked to the spray.

• Bitter taste: reported by 9.3% of azelastine users vs. 1.3% of placebo.
• Nosebleeds: 6.6% with azelastine vs. 4% with placebo.
• Other complaints included tiredness and, less commonly, dizziness.

Investigators noted that longer or more frequent dosing can increase drowsiness and local nasal irritation. Participants with recurrent nosebleeds or recent nasal surgery were advised to seek medical guidance before use.

What clinicians recommend and who should be cautious

Independent physicians not involved in the study weighed in on practical use. They emphasized that azelastine can be useful for allergy relief and might be considered for short-term prevention in certain situations.

Practical tips for use

• Available over the counter as azelastine HCl 0.1% or 0.15% for seasonal allergies.
• Follow label directions; typical OTC dosing is once or twice daily for allergic symptoms.
• Some clinicians suggest short-term use during travel, high-exposure events, or at first signs of illness.

Safety precautions

• Avoid alcohol and sedatives while using azelastine due to increased drowsiness risk.
• Be careful when driving or operating heavy machinery if you feel dizzy.
• People allergic to azelastine or any spray ingredients should not use it.
• Limited safety data exist for pregnancy and breastfeeding; consult a clinician first.

Experts stressed that azelastine is not a replacement for vaccination. Vaccination remains the primary defense against severe COVID-19. The spray, if helpful, would be an adjunctive measure alongside testing and public health steps.

Limitations of the study and next steps

The trial offers encouraging signals but has several limits that must be addressed in future work.

• Single-center study in Germany with a largely homogeneous participant pool.
• Most participants identified as white and were young adults, limiting generalizability.
• The sample size was modest for a phase 2 trial; larger, diverse trials are needed.
• Long-term safety and optimal dosing in broader populations remain uncertain.

Researchers and clinicians say confirmatory trials should include varied age groups, people with different health backgrounds, and multiple geographic regions to validate these early findings.