A common over-the-counter allergy nasal spray may significantly reduce the risk of COVID-19 infection, according to a mid-stage clinical trial published Tuesday in JAMA Internal Medicine. Researchers found that daily use of the spray, containing the antihistamine azelastine, lowered infection rates by 67 percent compared with a placebo.
The randomized, double-blind, placebo-controlled Phase 2 trial was conducted at Saarland University in Germany between March 2023 and July 2024. It enrolled 450 healthy adults, with half assigned to use the azelastine spray three times daily and the other half receiving a placebo. Both groups were balanced in terms of vaccination and prior infection status.
After 56 days, just 2.2 percent of participants using the spray contracted COVID-19, compared with 6.7 percent in the placebo group. Those who did become infected while using the spray also tested positive for a shorter duration—3.4 days on average versus 5.1 days—suggesting quicker viral clearance. Infections occurred later in the trial among spray users as well, hinting at a possible protective delay against early exposures.
The spray also appeared to protect against other respiratory illnesses. Participants using azelastine experienced fewer total respiratory infections—21 compared with 49 in the placebo group—particularly fewer rhinovirus cases, the leading cause of the common cold. Previous studies have suggested that azelastine may act broadly against viruses entering through the nasal passages, though the exact antiviral mechanism remains unclear.
Researchers caution that the findings are limited. The trial involved a relatively small number of infections, was conducted at a single German site, and primarily enrolled healthy white women ages 20 to 46. Additionally, the study was funded by a pharmaceutical company that produces an azelastine spray, though not the U.S. over-the-counter version. Larger, more diverse studies will be needed to confirm these results.
The findings come at a time when U.S. access to COVID-19 vaccines has narrowed under new federal guidance, leaving many children, pregnant individuals, and adults under 65 with limited or no access. Experts warn this could leave vulnerable groups without critical protection during respiratory virus season.
With vaccines restricted and respiratory infections on the rise, an inexpensive, widely available nasal spray could offer a valuable supplemental defense. Reported side effects were mild, including bitter taste, nosebleeds, and fatigue.
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