What are the first signs of food intolerance?

Food intolerance is a difficulty digesting or reacting to a food, rather than an immediate immune emergency. Symptoms may build gradually and can return when the same food is eaten. The pattern is usually digestive: bloating, cramping, excess wind, loose stools, or feeling sick. Read more about [Bloating](/symptoms/bloating/) and [Diarrhoea](/symptoms/diarrhoea/).

Symptoms can have many causes, so an episode does not prove that one food is responsible. A food allergy can cause a faster reaction with hives, swelling, wheezing, or breathing difficulty and needs urgent attention.

Keep a simple food and symptom diary: record what you ate, the portion, when symptoms began, and how long they lasted. Avoid making several major exclusions at once, because that can hide the pattern and reduce dietary variety.

Arrange a clinical assessment if symptoms recur. A clinician may review the diary and suggest [Food Intolerance Testing](/treatments/diagnostics-and-screening/food-intolerance-testing/), while [Nutrition Counselling](/treatments/lifestyle-and-wellness/nutrition-counselling/) can help you remove or replace foods safely.

Seek urgent help for trouble breathing, swelling of the lips or tongue, faintness, or a rapidly spreading itchy rash after eating. Contact a clinician promptly for persistent vomiting or diarrhoea, blood in the stool, unexplained weight loss, or symptoms that repeatedly disturb sleep.

Which symptoms and timings make intolerance more likely? Could another digestive condition explain this pattern? Should I avoid a suspected food, and how can I maintain balanced nutrition while testing that change?