If you’re among the millions of Americans with food allergies, you may want to add sesame to your watch list. It’s a more common allergen than previously believed. That’s the conclusion of researchers who conducted a survey in response to an appeal from the FDA to investigate the prevalence and severity of sesame allergies. And even if you think you don’t have any food allergies, sesame should still be on your radar—since this allergy seems to be underdiagnosed.

Research findings: The report, published in JAMA Network Open, was based on a national, demographically balanced sample of about 80,000 adults and children who were surveyed by phone and online about self-reported and doctor-diagnosed sesame reactions. (Parents were queried about their children.)

More than 1.5 million children and adults have a current sesame allergy, and more than 1.1 million report either a physician-diagnosed sesame allergy or a history of self-reported symptoms, according to the survey results, which were generalized to the US population. The majority of the surveyed individuals also reported having at least one other food allergy, predominantly peanut, tree nut, egg and/or milk allergies.

“Our study shows sesame allergy is prevalent in the US in both adults and children and can cause severe allergic reactions,” explained study coauthor Ruchi S. Gupta, MD, MPH, a professor of pediatrics and medicine at the Feinberg School of Medicine at Northwestern Health.

The report warned that many sesame allergies remain undiagnosed. And unlike allergies to such foods as milk and eggs, which tend to develop early in life and are often outgrown by adolescence, sesame allergy affects roughly equal numbers of children and adults.

Sesame is not among the eight foods and/or food groups (peanuts, milk, shellfish, tree nuts, eggs, wheat, soy and fish) that the FDA mandates must be listed on food labels. Sesame is, however, labeled in the European Union and many other countries.

“It’s important to advocate for labeling sesame in packaged food,” Dr. Gupta explained in a written statement. “Sesame is in a lot of foods as a hidden ingredient. It is very hard to avoid.”

The danger: Sesame seeds are frequently concealed in foods, including tahini, tempeh, baked goods and candies, or are misleadingly labeled (for example, as “benne”), potentially exposing unsuspecting consumers to serious allergic reactions, ranging from mild symptoms, such as an itchy throat, to life-threatening anaphylaxis.

Smart: Anyone with suspected or known food allergies should always carry an epinephrine auto-injector. The devices rapidly inject adrenaline to halt a serious allergy attack, usually marked by sudden dizziness, skin reactions, a rapid and weak pulse and difficulty breathing.

While the FDA weighs whether to add sesame to its list of potential allergens that must appear on food labels, look for uncommon ingredient names that indicate the presence of sesame—especially if you have a suspected or known food allergy. According to Food Allergy Research & Education (FARE), these names may include…

Benne, benne seed, benniseed
Gingelly, gingelly oil
Sesame flour, sesame paste and sesame salt (gomasio)
Sesamum indicum
Sim sim
Tahini, tahina, tehina

Warning about sesame oil: Even though most people with specific food protein allergies can safely eat highly refined oils made from those foods (for example, highly refined peanut or soybean oil), sesame oil is not refined, so it should be avoided by people with a sesame allergy, according to FARE.

The seeds also can lurk in flavorings, ethnic foods, bread crumbs, cereals, chips and crackers, falafel, sushi, flavored rice, noodles, risotto, herbal drinks, snack foods and some vegetarian burgers. Unlabeled sesame may be found in certain spice blends. Nonfood items such as cosmetics (including soaps and creams), medications and nutritional supplements also may contain sesame, either without labeling or sometimes under the scientific name for sesame, Sesamum indicum. If you have any question as to whether a food or nonfood product contains sesame, call the manufacturer.