A food allergy occurs when the body’s immune system mistakenly identifies a harmless food protein as a threat, triggering a protective response. This can lead to a range of symptoms, from mild discomfort to severe, potentially life-threatening reactions. The question of how long a food allergy lasts has two main interpretations: the duration of an immediate allergic reaction and whether the allergy itself can permanently disappear.
The Immediate Aftermath: How Long Does an Allergic Reaction Last?
An acute food allergic reaction can manifest rapidly, often within minutes to two hours after consuming the offending food. The duration of these immediate symptoms can vary, typically lasting a few hours in mild cases. Factors influencing the length and severity of a reaction include the amount of allergen ingested and an individual’s specific sensitivity.
Some reactions may have lingering effects, such as skin rashes or fatigue, that can persist for one to two days. Additionally, a less common but serious concern is a biphasic reaction, where a second wave of symptoms occurs hours after the initial symptoms have subsided, sometimes up to 12 hours later or even days later. This possibility highlights the importance of medical monitoring following an allergic reaction, even if initial symptoms appear to resolve.
The Long View: When Do Food Allergies Go Away Permanently?
Many children can outgrow certain food allergies, particularly those to milk, egg, wheat, and soy. This is often attributed to the maturation of the child’s immune system.
For milk allergy, some studies indicate that around 80% of children may outgrow it by ages 3-5, with others developing tolerance into their early teenage years. For egg allergy, approximately half of children outgrow it by age five, with close to 90% resolving by age six.
Wheat allergy can resolve in about 45% of children by age five, and around 65% by age 12. Soy allergies are commonly outgrown, with studies showing that many children, up to 70%, may outgrow their soy allergy by age ten. An allergist must confirm if an allergy has been outgrown.
Allergies That Often Persist
While some food allergies commonly resolve, others are more likely to be lifelong. Allergies to peanuts, tree nuts, fish, and shellfish frequently persist into adulthood.
Only about 10-20% of children with a peanut allergy outgrow it. Similarly, around 9-14% of children with tree nut allergies outgrow them.
Fish and shellfish allergies are less commonly outgrown and often remain permanent. Food allergies can also develop for the first time in adulthood, and these adult-onset allergies are long-lasting. Their persistence often relates to different immune responses.
Managing Food Allergies and Confirming Changes
Allergists diagnose and manage food allergies. They conduct tests like skin prick or blood tests to identify specific allergens. To confirm if an allergy has been outgrown, especially in children, an allergist may recommend a supervised oral food challenge. This involves carefully consuming increasing amounts of the suspected food in a controlled medical setting while being monitored.
Distinguishing a food allergy from a food intolerance is important. A food allergy involves an immune response, even to tiny amounts of food, and can be life-threatening. In contrast, a food intolerance affects the digestive system, is not immune-mediated, and symptoms are generally less severe and dose-dependent. Severe allergic reaction symptoms, such as difficulty breathing, throat or tongue swelling, or a rapid, weak pulse, require immediate emergency medical attention.