Your medicine cabinet could be packing more than just cold and flu relief.

A groundbreaking new study found that a widely available over-the-counter nasal spray may help healthy adults fend off COVID-19.

The news comes amid a late-summer surge driving up cases across the country — including in New York City.

The spray in question? Azelastine — an antihistamine that’s been safely used in the US since the 1990s to treat allergies. It’s sold OTC in the 0.15% concentration as Astepro Allergy.

Recent research suggests it might do more than ease sniffles. A study from last year found azelastine could reduce the viral load in COVID-19 patients, helping slow the progression of infection.

Curious about whether the nasal spray could also act as a preexposure prophylaxis — that is, stopping infections before they start — researchers in Germany put it to the test.

The team recruited 450 healthy adults in Germany aged 18 to 65 — nearly all had received at least one dose of the COVID-19 vaccine.

The participants were split into two groups: one took a single puff of azelastine 0.1% in each nostril three times a day, while the other got a placebo.

Over the 56-day study period, both groups were tested twice a week for SARS-CoV-2, the virus responsible for COVID-19 infections.

By the end of the trial, just 2.2% of those using the azelastine spray had tested positive — compared to 6.7% in the placebo group.

“It was a small but significant result,” Dr. Bruce Hirsch, an an infectious disease specialist at Northwell Health, told The Post.

He pointed out that previous studies have shown the antihistamine spray has antiviral properties.

“It kind of makes sense that if a medication is soothing the lining of the upper respiratory tract, that there’s going to be less inflammation,” Hirsch explained. “With less tissue disruption, there’ll be less opportunity for viruses to get going and to cause mischief.”

That wasn’t the only win. Those using the spray took longer to get infected, were positive for fewer days and experienced fewer symptoms than those in the placebo group.

“Together, these results suggest that azelastine may provide meaningful protection against SARS-CoV-2 infection,” the study authors wrote Tuesday in JAMA Internal Medicine.

The spray was also well-tolerated. Only two participants taking azelastine reported serious side events, and neither was linked to the treatment.

“This is something that that I’m going to keep in the back of my mind,” Hirsch said. “I think it’s a benign intervention for patients and it’s something that we might include during a busy viral cold and flu season.”

Still, he cautioned that the spray isn’t a silver bullet.

“This doesn’t replace all the other things that we need to do to prevent ourselves from getting sick and getting COVID in the first place,” Hirsch said.

With its strong safety profile, OTC availability and ease of use, the researchers said that azelastine serves as a practical, scalable on-demand tool for preventing COVID-19 infections in high-risk situations, such as large gatherings or during travel.

They’re calling for further research into the nasal spray — not only for COVID-19 but also to see if it can protect against other respiratory viruses, including respiratory syncytial virus (RSV) and the flu.

The findings come as the US braces for another active respiratory virus season, with a new COVID-19 variant already pushing up case numbers nationwide.

Last week, the US Food and Drug Administration approved updated COVID-19 shots designed to tackle the evolving virus. But the agency tightened rules on who can get them.

Under the new guidelines, only people 65 and older automatically qualify. Younger adults and children must now show that they have an underlying condition — like asthma or obesity — that increases their risk of serious illness.

This policy shift could create new barriers for large swaths of the public, reversing previous guidance that recommended yearly COVID-19 vaccines for everyone 6 months and older.

“These vaccines are available for all patients who choose them after consulting with their doctors,” US Health and Human Services Secretary Robert F. Kennedy Jr. said in a post on X.

But whether you’ll actually be able to get one at your local pharmacy depends on where you live, as providers scramble to navigate the shifting regulatory landscape.

For instance, CVS will now require a prescription for COVID-19 vaccines in Washington, DC, and 13 states — including New York — due to local restrictions, even for those who meet the new eligibility criteria.

In Massachusetts, New Mexico and Nevada, the retail pharmacy giant cannot administer the vaccine without approval from the federal advisory panel ACIP, due to state laws — even if a patient has a prescription.

The advisory committee is set to meet in mid-September, and its recommendations will carry major weight, including determining who qualifies for free, insurance-covered COVID-19 vaccines.

For its part, Walgreens said it is “prepared to offer the vaccine in states where we are able to do so,” according to CBS News.