FacebookFood Allergy vs. Food Intolerance
A food allergy occurs when the immune system mistakenly identifies a food as harmful and triggers an immune response. During this reaction, the body produces antibodies called Immunoglobulin E (IgE), which can lead to symptoms ranging from mild to severe. In some cases, a food allergy can cause anaphylaxis, a life-threatening allergic reaction that requires immediate medical attention.
A food intolerance does not involve the immune system. Instead, it is usually related to difficulty digesting or processing certain foods or food components. While uncomfortable, food intolerances are generally not life-threatening.
Food allergies are most common in young children, although they can develop at any age. In the United States, the foods responsible for most allergic reactions are milk, eggs, soy, wheat, peanuts, tree nuts, fish, shellfish, and sesame.
Some medical conditions can cause symptoms similar to food intolerance but require different evaluation and treatment. For example:
- Celiac disease is an autoimmune disorder in which gluten triggers damage to the small intestine.
Irritable bowel syndrome (IBS) is a common digestive condition whose symptoms may be triggered by certain foods.
What Is a Food Allergy?
A food allergy occurs when the immune system overreacts to a food that is normally harmless, such as peanuts, tree nuts, milk, eggs, fish, shellfish, soy, wheat, or sesame.
Allergic reactions typically occur within minutes to a few hours after eating the food and can affect multiple organ systems throughout the body. Even a very small amount of the trigger food may be enough to cause a reaction.
Common symptoms of a food allergy include:
- Hives or itchy skin
- Skin rash
- Swelling of the lips, tongue, face, or throat
- Wheezing or shortness of breath
- Difficulty swallowing
- Dizziness or feeling faint
- Nausea, vomiting, or diarrhea
- Anaphylaxis
Unless the allergy is outgrown, exposure to the food will typically trigger a reaction each time it is consumed.
What Is a Food Intolerance?
A food intolerance occurs when the body has difficulty digesting or processing a particular food or ingredient. People with a food intolerance can often tolerate small amounts of the food without experiencing symptoms.
Symptoms may develop gradually and are typically limited to the digestive system. While they can be uncomfortable and affect quality of life, they do not usually cause severe or life-threatening reactions.
Common symptoms of food intolerance include:
- Bloating
- Gas
- Abdominal cramping
- Stomach pain
- Nausea
- Diarrhea
- Constipation
Lactose Intolerance: A Common Example
One of the most common food intolerances is lactose intolerance, which occurs when the body does not produce enough of the enzyme lactase to properly digest lactose, the natural sugar found in milk and dairy products.
Symptoms may include:
- Bloating and gas
- Stomach cramps
- Diarrhea
- Constipation
- Nausea
Some people can tolerate small amounts of lactose, while others may need to avoid lactose-containing foods altogether. Lactase enzyme supplements may help some individuals digest lactose-containing foods more comfortably.
Shared Symptoms
Food allergies and food intolerances can sometimes cause similar symptoms, including:
- Nausea
- Stomach pain
- Diarrhea
- Vomiting
Because these symptoms overlap, it can be difficult to determine the cause without medical evaluation.
Symptoms More Commonly Associated with Food Intolerance
- Gas
- Bloating
- Abdominal cramping
- Heartburn
- Headaches
- Irritability or difficulty concentrating
Symptoms More Commonly Associated with Food Allergy
- Hives or itchy skin
- Skin rashes
- Wheezing or shortness of breath
- Chest tightness
- Swelling of the face, lips, tongue, or throat
- Difficulty swallowing or breathing
- Dizziness or fainting
- Anaphylaxis
Is Food Sensitivity the Same as Food Intolerance?
Not exactly.
Some people experience symptoms after eating certain foods but do not have a food allergy, food intolerance, or celiac disease. These reactions are often referred to as food sensitivities.
Food sensitivities can cause symptoms such as:
- Stomach pain
- Fatigue
- Joint discomfort
- Headaches
- Skin rashes
- Brain fog
One example is non-celiac gluten sensitivity, in which people experience symptoms related to gluten consumption but do not have celiac disease or a wheat allergy.
Food sensitivities are often identified through an elimination diet in which suspected foods are removed and gradually reintroduced under the guidance of a healthcare professional.
Treatment and Prevention
If You Think You Have a Food Allergy
If you experience symptoms of a food allergy, talk with your healthcare provider or an allergist. Testing may help identify the food you’re allergic to.
If a food allergy is diagnosed, the most effective treatment is strict avoidance of the allergen.
If You Think You Have a Food Intolerance
Keeping a food and symptom diary can help identify patterns between what you eat and how you feel.
Your healthcare provider may recommend temporarily eliminating certain foods and then reintroducing them to determine whether they are contributing to symptoms.
Before making significant dietary changes, consult a healthcare professional or registered dietitian to ensure your nutritional needs are being met.
Regardless of whether you have a food allergy or a food intolerance, learning how to read ingredient labels carefully is an important part of managing your condition.
When to See a Doctor or Allergist
If you consistently experience symptoms after eating certain foods, schedule an appointment with your healthcare provider to determine the cause.
If you have a food allergy, you may be at risk for anaphylaxis, even if previous reactions have been mild. Your healthcare provider may recommend carrying an epinephrine auto-injector and will teach you how and when to use it.
Call 911 immediately if someone experiences symptoms of anaphylaxis, including difficulty breathing, throat swelling, severe dizziness, or loss of consciousness.
