Can you intentionally develop an allergy to something?

Every morning, Susan enjoys milk with her cereal, cream in her coffee, and butter on her toast. By lunch, she snacks on cheese or indulges in a cup of yogurt. Dinner often ends with a serving of ice cream. These routines have been part of her life for years, but recent symptoms have made her rethink her habits.

Plagued by stomach cramps, bloating, and diarrhea, Susan faces a new reality. At 40, she joins the 30 to 50 million Americans who struggle to digest the sugars in dairy [source: Johns Hopkins Medicine]. Shocked by her lactose intolerance, she’s even more baffled when diagnosed with a full-blown milk allergy. How could she develop an allergy to something she’s consumed her entire life? Did her habits contribute to this condition?

Contrary to popular belief, allergies aren’t always present from birth. Many develop later in life. Allergies occur when the immune system overreacts. Almost any substance, from pet dander and pollen to certain foods, can trigger this overreaction at any time. When it happens, the immune system releases excessive histamine, leading to symptoms like nasal congestion, itchy eyes, hives, and digestive problems.

Many individuals with adult-onset allergies may not be encountering these symptoms for the first time, even if they believe otherwise. It’s probable they experienced a prior allergic reaction, perhaps too early in life to recall or too mild to recognize. In Susan’s situation, she had unknowingly lived with a mild milk allergy for years, and dietary changes triggered a stronger immune response [source: Stewart].

While food is a frequent trigger for adults diagnosed with new allergies, it’s not the sole cause. Half of all newly identified allergies emerge in adulthood, often involving common, everyday substances. Your allergy might have intensified over time, or increased exposure to the allergen could be the reason. For instance, adopting a dog after limited prior exposure might lead to a pet dander allergy due to heightened contact [source: Peri].

Managing allergies begins with awareness. After consulting a professional to identify your allergens, you can create strategies to minimize exposure. This puts you on the path to relief — or, like Susan, learning to enjoy alternatives like soy yogurt!