For most people, eating is a fundamental part of daily life, but for some, certain foods can provoke dangerous, even life-threatening reactions. A food allergy arises when the immune system mistakenly labels a harmless food component (an allergen) as a threat. This misidentification triggers the body to produce allergy-specific antibodies (immune proteins) that target these substances. Symptoms can appear anywhere from minutes to hours after exposure and range from mild discomfort to severe crises. Unlike food intolerance, which is a non-immune, chemical response causing usually mild issues, true allergies are becoming more prevalent, affecting about 10 % of infants and 2 % of adults in Australia. Because untreated allergies carry serious risks, early diagnosis by a healthcare professional is essential to learn how to manage the condition and respond if a reaction occurs.
Allergy or Intolerance
People often confuse food intolerances with allergies since some signs overlap, but intolerances stem from chemical processes rather than immune activity. They do not involve immune-system antibodies, rarely lead to serious reactions, and won’t appear on standard allergy tests. Nevertheless, intolerances or reactions to additives can still cause wheezing, asthma, hay fever, or hives. Occasionally, adverse responses after eating signal other issues, like food poisoning, toxicity, enzyme deficiencies, food aversion, or skin irritation on contact. If you suspect an allergy or intolerance, it’s best to consult your GP for an accurate diagnosis.
Food allergy symptoms
Even tiny amounts of a triggering food can spark a reaction, which may be life-threatening. Reactions often involve the face, digestive tract, skin, cardiovascular system, or lungs, and can differ in presentation and severity each time.
- Mild to moderate symptoms:
- Itching, burning, or swelling around the mouth and lips
- Puffiness of the face or eyes
- Abdominal pain
- Nausea and vomiting
- Skin rash (eczema) or hives
- Diarrhoea and stomach cramps
- Severe reactions / Anaphylaxis:
- Swelling of the tongue
- Throat tightness or swelling
- Difficulty speaking or swallowing
- Respiratory distress (coughing, wheezing, asthma)
- Weak or rapid pulse
- Pale, limp appearance (especially in children)
- Dizziness or fainting
- Heart palpitations
- Shock or circulatory collapse
- Anaphylaxis, a medical emergency
Some allergies are harder to recognize, especially in young children, where symptoms like reflux, colic, or chronic diarrhoea might not be immediately linked to a food allergy.
Areas affected by food allergy
Allergic reactions can impact multiple parts of the body, including:
- Eyes
- Nose
- Mouth
- Throat
- Skin swelling
- Digestive organs
- Skin
- Lungs
- Central nervous system
Reaction severity
The intensity of an allergic response can vary greatly and is influenced by factors such as:
- The strength of the allergy itself
- Quantity of allergen consumed
- Whether the allergen is eaten alone or with other foods (e.g. whole egg vs. egg in a muffin)
- The form of the allergen (liquids absorb faster; cooking may reduce allergenicity)
- Recent exercise
- Alcohol consumption
- Coexisting asthma
- Phases of the menstrual cycle
- Specific areas of the body involved
Main causes of food allergies
Allergic reactions can occur via ingestion, inhalation, or even skin contact. While any food can be problematic, eight major groups account for approximately 90 % of cases:
- Eggs
- Milk and dairy products
- Peanuts
- Tree nuts (e.g. almonds, cashews, brazil nuts, walnuts, pine nuts)
- Fish
- Shellfish
- Wheat
- Soybeans
Seeds such as sesame and mustard are also significant allergens in some regions. Cross-reactivity can occur; for example, someone allergic to prawns may also react to crab or lobster, so related foods should be approached with caution.
Can food allergies go away?
Many children eventually outgrow allergies to cow’s milk, soy, wheat, or eggs. However, allergies that first appear in adulthood are more likely to persist.
Diagnosing food allergies
Consistent symptoms after eating a specific food suggest an allergy, but variability in reactions can complicate diagnosis. A GP, clinical immunologist, or allergy specialist should confirm the condition, select appropriate tests, and help you with ongoing management. Avoid self-diagnosis, as it can be both uncomfortable and risky.
Allergy tests
To identify the allergen, specialists review your history and may use skin prick or blood tests to detect specific IgE antibodies. In some cases, an oral food challenge or temporary elimination diet may be performed, but only under medical supervision.
Managing and treating food allergies
After diagnosis, strict avoidance of the trigger is essential. Since accidental exposure can occur, work with an allergy specialist to prepare for emergencies:
- Always carry an adrenaline autoinjector (e.g. EpiPen) and your ASCIA Action Plan
- Learn to recognize early signs and emergency steps
- Carefully read food labels
- Inform restaurant staff about your allergy
- Notify school or childcare personnel for allergic children
- Prevent cross-contamination in the kitchen
- Confirm with your pharmacist that medications are free of allergens (e.g. lactose)
ASCIA Action Plan
Those diagnosed with food allergies should maintain an ASCIA Action Plan (Australasian Society of Clinical Immunology and Allergy) and always carry an adrenaline (epinephrine) autoinjector if prescribed.
What to do during an allergic reaction?
If allergic reaction is:
- Severe or anaphylactic reactions require immediate emergency help, call for medical assistance right away.
- For mild reactions:
1. Stop consuming the suspected food immediately 2. Over-the-counter antihistamines may ease symptoms