Food Allergy or Food Intolerance: Know the Difference

food allergy or intolerance

Food Allergy vs Food Intolerance

Food allergy and food intolerance are commonly confused, as food intolerance symptoms sometimes resemble food allergy symptoms. To make things even more perplexing, some foods can cause both.

A food allergy happens when the immune system wrongly sees the food as hostile and the body’s defense mechanism springs into action. This produces a range of symptoms that can vary from mild itching to severe breathing difficulties or even shock. These symptoms usually happen immediately after eating the food.

In food intolerance, the immune system is usually not involved, symptoms take much longer to develop, and are generally not life-threatening. However, food intolerance can adversely affect long-term quality of life.

Difference in Symptoms

Both food intolerance and food allergies produce a wide spectrum of symptoms. These may include:

  • Cutaneous (skin) symptoms
  • Vascular symptoms
  • Gastrointestinal symptoms
  • Respiratory symptoms

In food allergies, the most common reactions are cutaneous symptoms, such as hives and swelling of the lips or throat. Additional symptoms can include bronchospasm, nausea, vomiting, and dizziness. Reactions involving two or more organ systems, also known as anaphylaxis, may occur, and rarely may be life-threatening.

Food allergies are highly specific and occur only in response to particular food components, A minute amount of the allergen is sufficient to set off a reaction. In contrast, food intolerance is non-specific and requires a threshold amount of food to produce symptoms. This results in primarily gastrointestinal symptoms such as gas, abdominal pain or diarrhea. It’s not life-threatening, but it can be very uncomfortable.

The symptoms of food allergy and intolerance can also be caused by other conditions, so it is important to see your doctor for a medical diagnosis.

Other important differences between food allergies and food intolerances include:

  • Time: Symptoms of a true allergic reaction usually occur within minutes of consuming a food allergen, and a tiny amount may trigger a reaction. In contrast, food intolerance symptoms are delayed after food is consumed and are elicited by a larger amount of the offending food.
  • Severity: Food allergies can cause dangerous symptoms, whereas food intolerances just make you feel uncomfortable. People with food allergies should avoid their trigger food, even in small quantities. Some people with intolerance can have smaller amounts of that food.
  • Diagnosis: Food allergies are diagnosed by an Allergist and involve blood and skin testing or oral food challenge. Diagnosis for food intolerance involves trial-and-error with food elimination and re-introduction, which can be done by a Registered Dietician or physician. Breath Hydrogen tests can be done for lactose intolerance.

Different Types of Food Allergies

  • Wheat Allergy

    This type of allergy, not to be confused with gluten intolerance, is due to proteins contained in wheat and is more common in children than in adults.

  • Cow’s milk allergy

    This is due to the proteins contained in the milk. It generally appears very early in infants and disappears in 90% of children after the age of three.

  • Egg allergy

    Certain proteins particularly found in egg white provokes allergic reactions more commonly seen in children than in adults.

  • Peanut allergy

    This is one of the most dangerous food allergies as peanut protein is food in numerous foods.

  • Soy allergy

    This often provokes allergic reactions in children. However, in most cases, children outgrow this allergy by the time they are of school age.

  • Tree Nut allergy

    Tree nuts such as walnuts, hazelnuts, almonds, and pistachios are common food allergens. In most cases, nut allergy persists throughout a person’s life.

  • Fish and Shellfish allergy

    Fish, crustaceans, and mollusks are also responsible for food allergies which generally persist throughout a person’s life. People who are allergic to fish are not necessarily allergic to shellfish, and vice versa, but they are often allergic to several types of fish.

  • Sesame allergy

    Sesame, a seed often found in Asian food and snack foods, contains proteins that can provoke an allergic reaction.

Different Types of Food Intolerance

  • Lactose intolerance

    Lactase is an enzyme found in the intestine which breaks down lactose (a type of sugar found in milk) into glucose and galactose. While these two molecules are tolerated by most people, insufficient lactase provokes the symptoms of lactose intolerance.

  • Histamine intolerance

    Histamine is a molecule that forms in products that ferment, mature or rot, such as processed meat, cured meat, mature cheese, wine, sparkling wine, beer, and vinegar, as well as in strawberries, tomatoes, and chocolate.
    Disorders such as skin rashes, flatulence or diarrhea have been observed and are due to a dysfunction of the enzyme diamine oxidase, involved in the breakdown of histamine.

  • Gluten intolerance

    Gluten is a component of various cereals (wheat, rye, barley) which can trigger a complex autoimmune reaction, meaning that the body directs the immune response against itself. This is referred to as a celiac disease.

How to Manage Food Allergies and Food Intolerance

The easiest way to manage a food allergy or intolerance is to eliminate the offending food/s from the diet. Sometimes, the body can tolerate the food if it is avoided for a time, then reintroduced in small doses, particularly for food intolerances.

Before you eliminate or reintroduce foods, seek advice from a specialist doctor and dietician.


It is important to consult your doctor to accurately diagnose food allergies and avoid unnecessary food restrictions, which can result in poor nutrition. Regular follow-ups with the allergist are also essential so that your food allergy can be monitored closely.

For more information about allergy treatment and prevention contact Dr. Amy Schiffman in Boca Raton, Florida. She is board-certified by the American Board of Allergy and Immunology. Get in touch with her today to schedule your appointment.

Please call the office to discuss your allergy evaluation needs, and medications to avoid in preparation for testing.

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