Food Allergy

Food allergies are a serious medical condition that affects a significant portion of the population. It is essential to understand the causes, symptoms, and management of food allergies to effectively deal with them when they occur. Food allergies involve an abnormal immune response to certain food proteins, which can lead to a range of symptoms from mild to life-threatening.

In this article, we will explore the stages, types, symptoms, and management of food allergies to help readers better understand this complex condition.

What is a Food Allergy?

A food allergy is an adverse immune response to a specific food protein. When an individual with a food allergy consumes the offending food, their immune system mistakenly identifies the protein as a harmful substance and produces antibodies called Immunoglobulin E (IgE). These IgE antibodies attach to specific cells, causing them to release chemicals such as histamine, which lead to the symptoms of an allergic reaction.

The severity of food allergy symptoms can vary from person to person, ranging from mild discomfort to life-threatening anaphylaxis. Common symptoms include skin reactions (e.g., hives, itching, swelling), gastrointestinal distress (e.g., abdominal pain, vomiting, diarrhoea), respiratory issues (e.g., wheezing, shortness of breath), and cardiovascular problems (e.g., rapid heartbeat, low blood pressure). In severe cases, anaphylaxis can occur, which is a medical emergency requiring immediate treatment with epinephrine (adrenaline).

Food Allergy in Children

Food allergies are particularly common in children, with many developing allergies early in life. Managing food allergies in children requires careful planning, education, and collaboration among parents, caregivers, and doctors.

• Prevalence:
  • Food allergies affect an estimated 6–8% of children up to the age of four (Valero-Moreno et al., 2024)
  • Milk, eggs, and peanuts are among the most common allergens in children
• Diagnosis:
  • Diagnosing food allergies in children involves a combination of medical history, physical examination, skin prick tests, and blood tests
  • Oral food challenges may be conducted under medical supervision to confirm a diagnosis
• Management:
  • Strict avoidance of the allergenic food is the primary management strategy
  • Reading food labels carefully and communicating with caregivers and school staff about the child's allergies is essential
  • Having an emergency action plan and carrying epinephrine auto-injectors (such as EpiPen) is crucial for managing severe reactions
• Prevention:
  • Early introduction of potentially allergenic foods, such as peanuts, may help prevent the development of allergies in some children
  • Exclusive breastfeeding for the first 4–6 months of life may offer some protective benefits, although evidence is variable

Managing food allergies in children requires a collaborative effort among parents, caregivers, schools, and doctors. By working together and staying informed, families can help ensure the safety and well-being of children with food allergies.

Food allergies can be classified based on the specific food proteins that trigger the immune response. Some of the most common types of food allergies include:

• Milk allergy: An immune reaction to proteins found in cow's milk and dairy products.
• Egg allergy: An allergy to proteins in egg whites, yolks, or both.
• Peanut allergy: A potentially severe allergy to proteins in peanuts.
• Tree nut allergy: An immune response to proteins in various tree nuts, such as almonds, cashews, and walnuts.
• Fish and shellfish allergies: Allergies to proteins in finned fish or shellfish, such as shrimp, crab, and lobster.
• Soy allergy: An allergy to proteins in soybeans and soy products.
• Wheat allergy: An immune reaction to proteins found in wheat.

These allergies can develop at any age, although they most commonly appear in childhood. Some individuals may outgrow specific food allergies, while others may experience persistent or lifelong allergies.

Recognising the early signs of a food allergy is crucial for prompt diagnosis and management. Some of the initial symptoms to look out for include:

• Itchy or tingling sensation in the mouth: Often the first sign after consuming an allergenic food.
• Swelling of the lips, tongue, or face: This can occur shortly after ingestion.
• Hives or rash: Raised, itchy welts may appear on the skin.
• Abdominal discomfort: This can manifest as cramping or pain.
• Nasal symptoms: Sneezing or a runny nose may develop.

If any of these symptoms occur after eating a specific food, it is essential to consult a doctor for proper evaluation and diagnosis. Early recognition and management of food allergies can help prevent more severe reactions.

Some individuals may experience minor discomfort, while others may have life-threatening reactions to food allergies. It is crucial to recognise the symptoms of a food allergy to ensure prompt treatment and management.

The more severe symptoms of food allergies include:

• Vomiting and diarrhoea: These gastrointestinal symptoms can occur shortly after eating.
• Coughing or wheezing: Respiratory issues may arise, indicating airway involvement.
• Difficulty breathing: This can include a tight throat or chest and may lead to anaphylaxis.
• Dizziness or lightheadedness: A feeling of faintness can accompany other symptoms.
• Anaphylaxis: A severe, life-threatening reaction that may include a rapid drop in blood pressure, loss of consciousness, and severe breathing difficulties.

How Does Food Allergy Affect Your Body?

When a person with a food allergy consumes an allergenic food, their immune system overreacts, leading to various symptoms that can affect multiple body systems. The severity of these reactions can vary from mild discomfort to life-threatening anaphylaxis.

Affected Body Parts

• Skin: Hives, itching, and eczema are common skin manifestations of food allergies.
• Respiratory system: Wheezing, coughing, and difficulty breathing can occur when the airways are affected.
• Gastrointestinal tract: Abdominal pain, diarrhoea, nausea, and vomiting are possible symptoms when the digestive system is involved.
• Cardiovascular system: In severe cases, anaphylaxis can cause a drop in blood pressure and rapid heartbeat, leading to dizziness or loss of consciousness.

Immune System Response

• When an allergenic food is consumed, the immune system releases IgE antibodies.
• These antibodies trigger the release of histamine and other chemicals, causing inflammation and the various symptoms associated with food allergies.

Long-term Effects

• Repeated exposure to allergens may lead to ongoing symptoms in some individuals, particularly in conditions such as eczema or asthma.

The development and progression of food allergies can be divided into several stages:

• Sensitisation: This initial stage occurs when the immune system first encounters the food allergen and produces IgE antibodies specific to that protein. Sensitisation does not always result in a clinical allergic reaction, but it is a prerequisite for developing a food allergy.
• Elicitation: In this stage, the sensitised individual consumes the allergenic food, and the IgE antibodies bound to specific cells recognise the allergen, leading to the release of chemicals that cause allergic symptoms.
• Chronic allergic inflammation: With repeated exposure to the allergen, some individuals may experience persistent low-grade symptoms or develop additional sensitivities to other foods or environmental allergens.

Understanding these stages can help in the diagnosis and management of food allergies, as well as in developing strategies for prevention.

Food allergies occur when the body's immune system mistakenly identifies certain food proteins as harmful and triggers an allergic reaction. Several factors can contribute to the development of food allergies, and understanding these causes can help in prevention and management.

• Common allergenic foods:
  • Majority of food allergies are caused by 9 food items, including eggs, peanuts, milk, shellfish, soy, tree nuts, wheat, and fish (Daley et al., 2025)
  • However, any food has the potential to cause an allergic reaction
• Immune system overreaction:
  • In individuals with food allergies, the immune system mistakenly identifies a food protein as a threat and launches an allergic response
  • Genetic predisposition can increase the likelihood of developing a food allergy
• Other factors:
  • The presence of other allergies, asthma, or eczema may increase the risk of developing a food allergy
  • Delaying the introduction of allergenic foods does not prevent allergies and may even increase the risk for some foods, such as peanuts

By understanding the causes of food allergies, individuals can take steps to minimise their risk and effectively manage their condition.

Several factors can increase an individual's likelihood of developing a food allergy:

Genetic factors

• Family history of allergic conditions (e.g., asthma, eczema, food allergies)
• Specific genes (e.g., the MALT1 gene associated with peanut allergy)

Eczema

• Moderate to severe eczema, especially early-onset
• Impaired skin barrier allowing absorption of food allergens
• Microbiome changes
• Overuse of antibiotics and hand sanitisers
• Urban living and sterile indoor environments
• Caesarean section births may alter the gut microbiome

Other factors

• Age (more common in children, especially toddlers and infants)
• Delivery method (caesarean section may increase risk)
• Diet and environment (cultural variations in diet and infant feeding practices)

Understanding these risk factors can help identify individuals who may be more susceptible to developing food allergies, allowing for early intervention and management strategies.

Food allergies can lead to a range of complications, some of which can be severe and even life-threatening. Anaphylaxis is the most serious complication, characterised by difficulty breathing, rapid heartbeat, dizziness, and a sudden drop in blood pressure. This condition requires immediate medical attention to prevent potentially fatal consequences. Food allergies can also exacerbate atopic dermatitis (eczema) and worsen respiratory issues such as asthma.

In children, food allergies may impact growth and development if the allergenic foods are significant sources of essential nutrients and are not adequately replaced by alternative foods. Careful management of food allergies, including avoidance of trigger foods and prompt treatment of reactions, is crucial to minimise the risk of these complications and ensure the overall well-being of affected individuals.

While there is no guaranteed way to prevent food allergies, some strategies may help reduce the risk:

Early introduction of allergens

• Introducing common allergenic foods (e.g., peanuts, eggs) to infants at 4–6 months
• Following guidelines for safe introduction based on individual risk factors

Breastfeeding

• Exclusive breastfeeding for the first 4–6 months of life
• Continuing breastfeeding while introducing solid foods

Maintaining a healthy microbiome

• Avoiding unnecessary antibiotic use
• Promoting a diverse diet rich in fibre and fermented foods
• Encouraging outdoor play and exposure to a variety of environments

Managing eczema

• Keeping skin moisturised and treating flare-ups promptly
• Using mild, fragrance-free skincare products

Consulting with a doctor, particularly for high-risk infants, can help develop a personalised prevention plan based on individual circumstances and family history.

Diagnosing food allergies involves a combination of medical history, physical examination, and specific tests:

Medical history

• Detailed account of symptoms, timing, and suspected trigger foods
• Family history of allergies and related conditions

Physical examination

• Assessment of overall health and signs of allergic reactions
• Examination of the skin, respiratory system, and gastrointestinal tract

Skin prick test

• Small amounts of suspected allergens are introduced into the skin
• Positive result indicated by a raised, itchy bump (wheal)

Blood tests

• Measurement of allergen-specific IgE antibodies in the blood
• Higher levels suggest a greater likelihood of allergy

Oral food challenge

• Gradual introduction of the suspected allergen under medical supervision
• Gold standard for confirming food allergy diagnosis

Additional tests, such as component-resolved diagnostics (CRD) or atopy patch tests, may be used in specific cases. An accurate diagnosis is essential for developing an effective management plan and avoiding unnecessary dietary restrictions.

1. Emergency Treatment for Severe Reactions

The first-line treatment for anaphylaxis, a life-threatening allergic reaction, is epinephrine (a non-selective alpha- and beta-adrenergic agonist). It is administered via an intramuscular injection (e.g., EpiPen) to rapidly counteract symptoms such as airway swelling and low blood pressure. Patients at risk of severe reactions should always carry an epinephrine auto-injector.

2. Symptom Management and Long-Term Control

Antihistamines like diphenhydramine, cetirizine, loratadine, fexofenadine, and chlorpheniramine help relieve mild allergic symptoms such as itching, hives, and nasal congestion. For chronic or severe cases, omalizumab can be prescribed to reduce the immune system's overreaction and prevent allergic responses.

Living with a food allergy necessitates a structured approach to maintain a healthy lifestyle and ensure ongoing medical care. Here are some key tips for managing your condition post-diagnosis:

• First, work closely with a nutritionist or dietitian to develop a diet plan that avoids allergenic foods while still ensuring you get adequate nutrition. This involves carefully reading food labels and avoiding cross-contamination.
• Second, always be prepared for emergencies. Carry your emergency medications, such as an epinephrine auto-injector (e.g., EpiPen), at all times and know how to use them. Educate your family, friends, and caregivers about your allergy and the proper response in case of an emergency.
• Third, schedule regular follow-ups with your doctor to monitor your condition and adjust your treatment plan as necessary. This helps you stay informed about any new treatments or guidelines.
• Lastly, make lifestyle adjustments to avoid accidental exposure to the allergen. This might include changing your eating habits, avoiding certain restaurants or foods, and communicating your allergy clearly when eating out or travelling.

Remember, managing a food allergy is an ongoing process. But with proper care, precautions, and regular medical check-ups, you can lead a healthy life.

If you suspect that you or your child may have a food allergy, it is important to see a doctor for proper diagnosis and treatment. Some signs that warrant a medical consultation include:

• Hives, itching, or swelling of the lips, face, tongue, or throat after eating certain foods.
• Wheezing, nasal congestion, or trouble breathing after eating certain foods.
• Abdominal pain, diarrhoea, nausea, or vomiting after eating certain foods.
• Dizziness, lightheadedness, or fainting after eating certain foods.
• A severe reaction known as anaphylaxis, which can cause difficulty breathing, a drop in blood pressure, and loss of consciousness.

If you have already been diagnosed with a food allergy, see your doctor if you have any changes in your symptoms or if you have any questions about your condition or treatment plan. Additionally, if you have had a severe allergic reaction, even if you have used your epinephrine auto-injector, seek emergency medical care right away. A second wave of symptoms (biphasic reaction) can occur hours after the initial response.

• Food allergies are a serious and potentially life-threatening condition where the immune system reacts to certain foods.
• Common food allergens include peanuts, tree nuts, milk, eggs, wheat, soy, fish, and shellfish, as well as sesame, but any food can cause an allergy.
• Symptoms of a food allergy can range from mild (hives, itching, swelling) to severe (trouble breathing, dizziness, loss of consciousness).
• Anaphylaxis is a severe, potentially life-threatening allergic reaction that requires immediate medical attention.
• Diagnosis of food allergies involves a combination of medical history, physical examination, and tests such as skin prick tests or blood tests.
• Management of food allergies includes strict avoidance of the allergen, carrying emergency medications (like epinephrine auto-injectors), and regular medical follow-ups.
• If you suspect a food allergy, see a doctor for proper diagnosis and treatment. If you have a diagnosed food allergy, work with your healthcare team to develop a comprehensive management plan.