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It’s been a while since we’ve heard much about COVID-19 prevention, but a new study from September 2025 grabbed attention.
Published in JAMA, it looked at whether a nasal spray called azelastine could help stop people from catching COVID-19. Let’s unpack why scientists tested it, how the trial worked, and what they found.
Why Test an Allergy Spray?
Back in 2021, researchers started wondering if antihistamines—drugs usually used for allergies—could help fight COVID-19. These medicines attach to certain receptors in the body, and scientists thought if a drug like azelastine or diphenhydramine (Benadryl) could latch onto the same spot the virus uses, it might block infection.
Early lab tests showed azelastine slowed the virus in a petri dish. But what happens in the lab doesn’t always happen in people, so researchers needed a solid trial to find out if it really prevents illness.
What Earlier Studies Found
Before this big new trial, smaller studies tested azelastine sprays on people who already had COVID-19. Participants got either a placebo or sprays at two strengths—0.02% and 0.1%—for 11 days. Those using the stronger 0.1% version had lower virus levels in their noses, meaning the spray might help clear the virus faster. But those trials didn’t test prevention—only treatment.
The 2025 Trial: Can It Stop Infection?
The new study focused on prevention. Researchers asked a simple question: if healthy people use azelastine nasal spray, can it keep them from getting COVID-19 at all?
The trial enrolled 450 healthy adults in Germany, ages 18 to 65, none of whom had COVID-19 at the start. They couldn’t take part if they were using other nasal medicines or antihistamines, or if they were pregnant or breastfeeding.
Volunteers were randomly split into two groups—one got the 0.1% azelastine spray, and the other got a placebo. Nobody knew which group they were in. They sprayed once per nostril, three times daily, for 56 days. If they were exposed to COVID-19 or started feeling sick, they increased to five times a day for three days.
Everyone took rapid tests twice a week, and if one turned positive, they got a PCR test to confirm infection.
What the Study Found
The main goal was to see how many people got infected by day 56. Researchers also tracked symptoms, how long positive tests lasted, and any side effects.
By the end:
Only 5 out of 227 people using azelastine got COVID-19 (2.2%), compared to 15 out of 223 on placebo (6.7%). That means the spray cut infection risk by about 69%, or a 4.5% absolute drop in cases.
Statistically, for every 23 people who used the spray for 56 days, one infection might be prevented. If the virus spreads more widely, that number could drop, meaning more benefit per user.
Relative vs. Absolute Risk
“Relative risk” shows how much something reduces your chances of infection, while “absolute risk” shows the real-world impact. If infections are already rare, absolute benefits look small—even when the relative effect sounds big. Both matter, depending on the situation.
How Safe Was It?
Interestingly, more general side effects happened in the placebo group. But nasal irritation and nosebleeds were a bit more common in the azelastine group. Other mild effects included a bitter taste, headaches, and tiredness.
One person developed Hashimoto’s thyroiditis, but that likely wasn’t from the spray.
Because the bitter taste was a top complaint, a newer over-the-counter version called Astapro was made. It’s sweeter, stronger (0.15%), and only needs one spray per day. Only 3–6% of users report a bad taste with it.
What’s in It?
Azelastine hydrochloride is the active ingredient, along with preservatives like benzalkonium chloride that prevent bacterial growth. Some people wondered if those preservatives might have helped fight the virus, but that seems unlikely—they’re found in lots of nasal sprays that don’t affect COVID-19.
Azelastine itself is a second-generation antihistamine. Unlike older ones like Benadryl, it doesn’t cause much drowsiness or cross into the brain. Still, long-term studies are needed to be sure it’s safe for extended use.
Where to Get It
The 0.1% version used in the study requires a prescription, but the 0.15% Astapro spray is available over the counter. The OTC bottle costs about $20–30, while the prescription version may be cheaper with insurance. Both can be used by adults and children.
How It Works
Azelastine seems to block the receptor sites the COVID-19 virus uses to latch onto nasal cells. By closing that “doorway,” the virus has a harder time getting in or spreading, possibly shortening how long you’re contagious.
When to Use It
The spray might be most useful during high-risk times—crowded places, flights, or after being around someone sick. It’s not meant for daily, indefinite use since long-term safety data is still limited. Think of it as a short-term layer of defense, not a constant routine.
Final Thoughts
Azelastine nasal spray isn’t a silver bullet, but it could lower your risk of catching COVID-19—especially during surges or travel. The biggest downside is that bitter taste, but the newer Astapro spray fixes that.
As always, check with your doctor before using it for anything beyond its labeled purpose, and keep an eye out for more research as scientists continue studying this simple but promising line of defense.
