There’s a variety of things that could be called “allergies,” and often are called allergies by those who experience reactions to various types of foods. Medically, an allergy is when there’s an immunological reaction to a particular food that causes hives, anaphylaxis, itching, sneezing, runny eyes, and the like. However, there are a number of reactions that individuals will often refer to as an allergy. Gastrointestinal distress, for example, of the type that lactose-intolerant individuals may experience when consuming milk.

The World Allergy Organization reports that, quote:

It is generally accepted that food allergy affects approximately 2.5% of the general population, but the spread of prevalence data is wide, ranging from 1% to 10%

In 2008, the Centers for Disease Control in the United States reported that, quote:

From 1997 to 2007, the prevalence of reported food allergy increased 18% among children under age 18 years. Eight types of food account for over 90% of allergic reactions in affected individuals: milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat.

In 2007, a study carried out in Poland took a look at the prevalence of children’s allergies in urban and rural environments found that in general, children who live in urban environments tend to have a higher prevalence of allergies while those in rural environments do not tend to. As the Journal of the American Medical Association Network highlights, quote:

food allergy prevalence estimates from these recent national surveys exceed 9% of US adults, suggesting that food allergy may affect more US adults than previously acknowledged. Although some children with food allergy develop natural tolerance, others retain their food allergy as they enter adulthood. Adults can also develop new food allergies, and evidence suggests that certain food allergies (eg, shellfish and fin fish) may be more likely than others to develop during adulthood.

In other words, allergies aren’t really all that uncommon, and the things that we tend to refer to as allergies even more so. The prevalence seems to be growing, too, but even if that wasn’t the case, you or someone you know likely has an allergy to something.