Astepro — An Allergy Spray That May Ward of Viruses Like Flu or COVID

Have you caught COVID-19 again? We have been surprised and disappointed that so many friends and family members have caught the SARS-CoV-2 virus this summer and fall. Even those who avoided earlier variants are now testing positive for the latest version of COVID-19. Maybe that is why we have been paying so much attention to an unexpected discovery involving an affordable over-the-counter medicine used for allergy symptoms. Astepro (azelastine) is an antihistamine nasal spray that is used to calm symptoms such as sneezes and congestion. It’s now being studied for something completely different — blocking viruses like SARS-CoV-2 and influenza.

How Does Astepro Work to Prevent COVID infections?

Let’s start with a bizarre twist to this tale of woe and intrigue. It goes back to the Brazilian jararaca snake. Researchers learned that the venom of the deadly jararaca inhibits an enzyme called angiotensin-converting enzyme (ACE). When someone is bitten by the jararaca, blood pressure drops precipitously. That’s because the venom of the snake binds to ACE.

Researchers harnessed the snake venom’s ability to interfere with the enzyme ACE and thereby lower blood pressure. The best selling blood pressure medicine in America is lisinopril, an ACE inhibitor. Over 18 million Americans take this drug every day to control hypertension. A somewhat similar medication called an angiotensin receptor blocker (ARB) is losartan. It is taken by over 14 million Americans. So, we owe the jararaca snake a debt of gratitude for guiding us to some of our most prescribed medications.

ACE, SARS-CoV-2 and COVID:

It turns out that the angiotensin-converting enzyme is not just involved in blood pressure regulation, though. It is also a receptor site on cell surfaces (European Journal of Clinical Microbiology & Infectious Diseases, Jan. 3, 2021). It turns out that the SARS-CoV-2 virus enters cells by attaching to the spike-like protein ACE2.

Because COVID is frequently airborne, we generally catch this disease by breathing in particles of the virus after an infected person coughs, sneezes or just exhales. The virus can linger in air for a long time, so we can catch COVID from the person ahead of us in line at the supermarket, bank or pharmacy.

Azelastine (Astepro) blocks ACE2 receptors on nasal cells. That may be why it seems to prevent the COVID virus from getting into cells. It may also reduce the ability of the virus to multiply. In a somewhat similar manner, Astepro might also work against rhinoviruses that cause colds and influenza viruses that make us sick with flu.

Improving the Taste of Astepro:

One of the most common complaints with the adult version of Astepro is its taste. A lot of people say that the nasal spray leaves a bitter taste in the mouth.

This reader offers a way around that:

Q. Astepro has been a great help for my seasonal allergies. I’ll now use it as a preventative against flu or COVID. The downside for many people is the price and the taste.

Here’s a solution. Astepro comes in a better-tasting children’s version. It is the same strength, except it has an additive so that the taste is not objectionable. Even better, it doesn’t seem to move off the shelf as well, so I frequently find it discounted at drugstores. Whenever I find it marked down, I typically stock up for my whole family!

A. Thank you for the helpful tip. Both children’s and adult versions of Astepro contain 205.5 mcg of azelastine per spray. We were excited to learn of a study showing that this over-the-counter antihistamine nasal spray can reduce the risk of coming down with COVID (JAMA Internal Medicine (Sept. 2, 2025). The authors mention the possibility that it may also have broader antiviral activity.

We will need larger clinical trials to verify the effectiveness of azelastine against COVID, cold or flu viruses before we can recommend routine use of this nasal spray. On the other hand, it seems reasonably safe. It may work best when used before travel or large gatherings, especially if accompanied by wearing an N95 face mask.

For now, Astepro should remain part of your allergy toolkit, not a substitute for vaccines or masks. But it’s an appealing example of how a familiar medicine might have hidden talents — and how science continues to uncover new tricks in old drugs.

Please share your own experience with COVID in the comment section below. If you have ever used Astepro we would love to hear your story. And if you think this article has merit, please share it with friends and family. We will bet that they will be surprised to learn an over-the-counter antihistamine nasal spray might do double duty against viral infections.