Allergy
Food Allergy vs Food Intolerance: What is the Difference?
A simple guide to the difference between immune allergic reactions and digestive food intolerances.
Patient information page | Last reviewed: June 2026
The quick answer
Food allergy involves the immune system and can sometimes be life-threatening. Food intolerance usually involves digestion and can cause uncomfortable symptoms such as bloating, gas, tummy pain, or diarrhoea, but it does not cause anaphylaxis.
Many people experience tummy pain, bloating, diarrhoea, rashes, or swelling after eating certain foods. It is common to wonder whether this is a food allergy or a food intolerance. The words are often used as if they mean the same thing, but they describe different medical problems.
Knowing the difference matters because food allergy may need strict avoidance and an emergency plan, while food intolerance is usually managed by adjusting the amount or type of food.
1. The core difference
Food allergy
Food allergy involves the immune system. The body reacts to a food protein, such as peanut, milk, egg, fish, shellfish, wheat, soy, or tree nuts, as if it is dangerous. In some people, a very small amount can trigger a serious reaction.
Food intolerance
Food intolerance usually involves digestion or sensitivity to a food component. It does not involve the same immune pathway as allergy. Symptoms often depend on the amount eaten, and small amounts may be tolerated.
2. Comparing the symptoms
| Feature | Food allergy | Food intolerance |
|---|---|---|
| System involved | Immune system. | Usually digestive system. |
| Amount of food | A tiny amount can sometimes cause a severe reaction. | Often depends on portion size. Small amounts may be tolerated. |
| Timing | Often starts within minutes to 2 hours, although some allergic conditions can be delayed. | Often develops gradually after eating, commonly over hours. |
| Common signs | Hives, swelling of lips or face, vomiting, wheeze, throat symptoms, breathing symptoms, dizziness, or collapse. | Tummy pain, bloating, gas, diarrhoea, nausea, or discomfort. |
| Severity | Can be life-threatening if anaphylaxis occurs. | Can be very uncomfortable but does not cause anaphylaxis. |
3. Common triggers
Common food allergy triggers
Peanut, tree nuts, cow's milk, egg, fish, shellfish, wheat, soy, sesame, and some other foods. The pattern can vary by age and region.
Common food intolerance triggers
Lactose, some fermentable carbohydrates, caffeine, alcohol, certain food additives, and some naturally occurring food chemicals can trigger symptoms in some people.
4. Managing the conditions
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Food allergy: the trigger food may need strict avoidance. Label reading, cross-contact planning, and safe eating-out habits are important.
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Emergency planning: people at risk of anaphylaxis may be prescribed adrenaline auto-injectors and a written allergy action plan.
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Food intolerance: complete avoidance is not always needed. A food and symptom diary can help identify the trigger and the amount that causes symptoms.
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Dietitian support: if many foods are being restricted, or if a child is affected, ask for medical and dietitian advice to protect nutrition and growth.
5. Safety reminders
- Do not test a suspected serious allergy at home.
- Keep a clear symptom diary, including timing, amount eaten, and symptoms.
- Do not remove major food groups from a child’s diet without advice.
- Ask your doctor whether allergy testing is appropriate for your symptoms.
- If you have been prescribed adrenaline auto-injectors, keep them accessible and in date.
Related guides
See also: Which Allergy Test Do I Need? and How to Recognize Anaphylaxis and Use an Adrenaline Auto-Injector.
When to get urgent help
Call emergency services immediately if food symptoms include swelling of the lips, tongue, or throat, difficulty breathing, wheezing, chest tightness, hoarse voice, collapse, severe drowsiness, or rapidly worsening symptoms. Use your adrenaline auto-injector first if you have been prescribed one and anaphylaxis is suspected.