Scientists gave mice an existing asthma drug before exposing them to peanut extract; 95% were protected from severe allergic reactions in the experiment

If you're reading ingredient labels at birthday parties, scanning menus twice, and carrying around an EpiPen wherever you go, this piece of science could be of interest to you. A 2025 study titled “Asthma drug shows promise in blocking food allergy reactions,” conducted by researchers at Northwestern, found that when mice received a pill containing Zileuton, an FDA-approved drug used to treat asthma, and were fed peanut extract, they had a surprisingly low response.

The mice, who were almost certainly going to suffer anaphylactic shock (a severe allergic reaction involving the whole body), did not show many symptoms. Dr. Stephanie Eisenbarth, co-senior author of the study and faculty member of the Feinberg School of Medicine at Northwestern, stated that they were shocked at how well it worked.

How an old asthma drug came to be used for peanut allergies


Zileuton has been around for years as an asthma treatment, but it had never been studied in the context of food allergies, until researchers uncovered a new biological pathway linking the gut to anaphylaxis. According to a 2025 peer-reviewed study titled “Cysteinyl leukotrienes stimulate gut absorption of food allergens to promote anaphylaxis in mice,” published in the journal Science, scientists discovered a gene called DPEP1 that codes for an enzyme which breaks down leukotrienes: inflammatory molecules that help allergens pass through the gut wall and into the bloodstream. Mice with a more active version of DPEP1 cleared leukotrienes faster, absorbed less peanut protein, and had less anaphylaxis as a result. Zileuton works on the same pathway from the opposite direction: instead of relying on the gene, it blocks the body from producing leukotrienes in the first place, achieving a similar protective effect with a single dose.

Most research into food allergies has focused on targeting the overactive immune system. However, this study shows that maybe it's how much allergen is actually getting through. This could also be the reason why some people will show a positive peanut allergy on a blood test but can still eat peanuts throughout their life. Eisenbarth suggests this pathway may help explain some cases that standard allergy testing would not detect.

Why this matters

More than 33 million people in the US suffer from at least one food allergy, as per Food Allergy Research & Education (FARE). Many of these people are adults who developed allergies later in life, and now navigate daily routines most people never think twice about, checking labels at parties, double-checking restaurant menus, and factoring allergy risk into travel plans.

Currently, there are only two FDA-approved treatments for food allergies, and they are not a cure. One is an oral immunotherapy that can cause reactions, and another is a costly injection to which not everyone will respond. A low-cost, ready-made drug that can temporarily reduce risk would be a new treatment option.

The catch

While it worked in mice, there’s no guarantee it will work the same way in humans. Mice can be a reasonably good stand-in for the human immune system, but the Northwestern team launched a phase one clinical trial in 2025 to test whether Zileuton works the same way in people, and that trial is now underway. Even with promising safety data so far, it could be years before the drug is actually prescribed for allergies.

Eisenbarth also says that researchers “never would have found this gene” without years of sustained investment in basic research, suggesting there’s likely much more to uncover in this area. It’s still unclear how factors like diet and gut microbiome might affect this pathway in humans. Still, this is an entirely new mechanism for the field, and watching mice go from 95% susceptible to anaphylaxis to 95% protected is a striking result.