Immunotherapy — controlled, careful exposure to an allergen — has been shown to reduce the severity of allergic reactions. Sometimes, it can all-but-eliminate the allergy altogether. Increasingly, researchers are finding this is true for dangerous peanut allergies, as well as the pollen allergies immunotherapy has been more commonly used to fight. Along the same lines, a growing body of evidence suggests that keeping fetuses, infants, and small children away from possible allergens actually increases — not decreases — their likelihood of developing an allergy to those foods.