Food Allergy: Symptoms, Causes & Treatment

Food allergy is a condition in which the immune system mistakenly treats a protein in a certain food as a harmful substance threatening the body, launching an immune reaction directed against it. Food allergy differs from food intolerance (such as lactose intolerance); the latter does not involve the immune system, its symptoms are often digestive and less dangerous, while food allergy may be severe and sometimes life-threatening.

Food allergy symptoms usually appear quickly within minutes to two hours of eating the causative food, and their severity varies: they may be mild like itching, a skin rash (hives), or lip swelling, or digestive like abdominal pain, nausea, vomiting, and diarrhea, or respiratory like sneezing and congestion. Its most dangerous form is the severe allergic reaction known as anaphylaxis, in which rapid multi-system symptoms appear such as difficulty breathing, throat swelling, low blood pressure, and dizziness, a life-threatening emergency needing an adrenaline injection immediately. The most common allergy-causing foods are known, including milk, eggs, tree nuts, peanuts, wheat, soy, fish, and shellfish, and their frequency differs between children and adults.

Diagnosing food allergy relies on linking symptoms to a certain food, confirmed by the doctor with skin tests or blood tests and sometimes a food challenge test under medical supervision. There is so far no treatment that removes the allergy in most people, so the cornerstone is strictly avoiding the causative food, carefully reading product ingredients, and watching for cross-contamination during food preparation. Most important for those at risk of a severe reaction: knowing how to recognize anaphylaxis symptoms, carrying a self-injectable adrenaline pen and using it immediately when needed, then calling emergency services. The good news is that many childhood allergies (such as milk and egg allergy) may fade with growth, while others (like nuts) tend to persist.

• Itching or a rash (hives) and swelling of the lips or face.
• Abdominal pain, nausea, vomiting, and diarrhea.
• Sneezing, congestion, and respiratory symptoms.
• Anaphylaxis (emergency): difficulty breathing, throat swelling, low blood pressure, dizziness.

• A mistaken immune reaction to a protein in a certain food.
• Common foods: milk, eggs, tree nuts, peanuts, wheat, soy, fish, shellfish.
• Genetic predisposition and a family history of allergy or asthma.

• Linking symptoms to a certain food (medical history).
• Skin tests or allergy blood tests.
• A food challenge test under medical supervision in selected cases.

The cornerstone

• Strictly avoiding the causative food, reading product ingredients, and watching for cross-contamination.

During a reaction

• Antihistamines for mild symptoms with the doctor's guidance.
• The self-injectable adrenaline pen immediately for anaphylaxis, then calling emergency services.

Many childhood allergies may fade with growth. This content is educational and does not replace consulting an allergist.

• Life-threatening anaphylaxis.
• Malnutrition or excessive food avoidance in children without supervision.
• Anxiety and impact on social quality of life.

• Avoiding the causative food and reading labels carefully.
• Informing restaurants and food providers of the allergy.
• Carrying an adrenaline pen for those at risk of a severe reaction and knowing how to use it.