- Researchers say people using a common allergy nasal spray, azelastine, were 69% less likely to contract COVID-19.
- Participants in the trial were also 71% less likely to catch the common cold than placebo users.
- However, larger trials are needed to confirm the findings in more diverse populations.
- Vaccination remains the gold standard for protection against severe illness from COVID-19.
A common allergy nasal spray may help lower the risk of contracting COVID-19, according to new research.
In a clinical trial of healthy adults, people who used azelastine nasal spray (Astepro, Astelin) regularly for nearly two months were significantly less likely to become infected with SARS-CoV-2 (the virus that causes COVID-19) compared to those who used a placebo.
The spray, widely available over-the-counter for allergic rhinitis (hay fever), also appeared to reduce some other respiratory infections, with only mild side effects reported. The findings were published online on September 2 in
Researchers at Saarland University Hospital in Germany ran a phase 2, double-blind, placebo-controlled trial between March 2023 and July 2024.
This means neither the participants nor the researchers knew who was getting the active spray and who was getting the placebo until after the study ended.
The study included 450 healthy volunteers aged 18 to 65. Almost all had been vaccinated against COVID-19 at least once, with a median of three doses, and none had signs of acute infection at the start.
Recruitment was open to the public and promoted through universities, pharmacies, and social media.
Participants were randomly assigned to one of two groups: one received azelastine 0.1% nasal spray, and the other received a placebo spray that looked and felt identical but did not contain the active medicine.
Both sprays contained common inactive ingredients such as hypromellose, sodium chloride, and purified water. The azelastine spray also had 1 mg/mL azelastine hydrochloride.
Participants used one puff in each nostril three times a day for 56 days. If they developed respiratory symptoms or had known exposure to COVID-19, they increased use to five times a day for three days.
Testing was a central part of the trial. Participants took a rapid antigen test for SARS-CoV-2 twice weekly, done by trained study staff.
Positive results were confirmed with PCR testing. Those with symptoms but negative COVID rapid tests were screened with multiplex PCR for a wide range of respiratory viruses, including:
The primary measure was how many people developed PCR-confirmed COVID-19 during the 56-day study period.
Secondary measures included the number of symptomatic COVID-19 cases, time to infection, duration of positive tests, and incidence of other respiratory infections.
Safety was monitored by tracking adverse events and serious adverse events.
Out of the 450 participants, 227 received azelastine spray and 223 received a placebo. Most were female (66%), and most identified as white (93%). The average age was about 33 years.
In the main analysis, 2.2% of people in the azelastine group tested positive for COVID-19 by PCR compared to 6.7% in the placebo group. This translates to about a 69% lower risk of infection for those using the active spray.
Participants using azelastine also tended to go longer before contracting COVID-19.
Among those who tested positive for COVID-19, the average time to infection was 31 days in the azelastine group versus 19 days in the placebo group.
The average duration of positive rapid tests was shorter with azelastine, at about 3.4 days, compared to 5.1 days with placebo.
The spray also appeared to help against other respiratory viruses. Rhinovirus, which often causes colds, was the most common non-COVID infection detected.
Only 1.8% of azelastine users tested positive for rhinovirus compared to 6.3% of placebo users, translating to about a 71% lower risk of infection.
Overall, 8.4% of azelastine users had at least one laboratory-confirmed respiratory infection during the study, compared to 18.8% of placebo users.
Side effects were generally mild and consistent with what is already known about azelastine. The most common issues were bitter taste, nosebleeds, and tiredness.
Bitter taste was reported by 9.3% of azelastine users compared to 1.3% of placebo users. Nosebleeds occurred in 6.6% of the azelastine group and 4% of the placebo group.
Serious adverse events were rare, and none were considered related to the spray. No deaths occurred during the trial.
The findings suggest that a widely available nasal spray, already approved for allergies, may offer an extra layer of protection against COVID-19 and possibly other respiratory infections.
However, the study was relatively small and conducted in a single location, so larger trials will be needed to confirm the results in more diverse populations.
Parth Bhavsar, MD, a board certified family medicine physician and founder of TeleDirectMD, explained that in addition to bitter taste, nosebleeds, and tiredness, you might experience dizziness when using azelastine. Bhavsar wasn’t involved in the study.
He advised against ingesting alcohol or sedatives while using azelastine and being cautious when driving or using heavy equipment.
Bhavsar further noted that azelastine is fine for long-term use and will not lead to rebound congestion syndrome like certain decongestant sprays do.
“The principal practical risk with prolonged or more regular dosing is dose-dependent drowsiness and local nasal burning/epistaxis [nosebleeds],” he told Healthline.
Bhavsar said that people with recurrent nosebleeds or recent nasal surgery should consult with a physician before using it.
Steven Goldberg, MD, MBA, chief medical officer at HealthTrackRx, said that people with a known hypersensitivity to azelastine or any of the spray’s other ingredients should also avoid using it. Goldberg wasn’t involved in the study.
The nasal spray is also not recommended for pregnant or breastfeeding people due to limited safety data, Goldberg told Healthline.
If you do opt to use it, Goldberg recommended an over-the-counter version (often labeled for seasonal allergies), containing azelastine HCl 0.1% or 0.15%.
Then, follow the instructions on the label, using it once or twice day at the directed dose.
“Consider short-term use during travel, high-exposure environments, or early symptom onset,” said Goldberg.
If you have any underlying health concerns or plan to use it for a longer period of time, he advises that you speak with your doctor first.
Finally, it should be noted that using azelastine cannot replace COVID-19 vaccination.
“While azelastine nasal spray shows early promise in viral load reduction, it should be viewed as a complementary tool — not a substitute — for vaccination, rapid testing, and other public health measures,” Goldberg concluded.
