Which food intolerance tests are accurate?

There is no single blood test that accurately identifies every food intolerance. Depending on the suspected problem, assessment may include a food-and-symptom record, a supervised elimination and reintroduction, or a specific breath or blood test.

Intolerance does not mean the same thing as food allergy. Allergy involves an immune reaction and may require skin testing, specific IgE blood testing or a medically supervised food challenge. Intolerance can arise from difficulty digesting a component such as lactose or from another digestive condition.

Commercial panels that report IgG reactions to many foods do not establish that those foods cause symptoms. A positive result can reflect exposure to a food, and broad panels may lead to unnecessary restriction.

Record what you eat, the amount, when symptoms begin and details such as bloating, pain, bowel changes, headache or flushing. Include medicines, menstrual timing and stress where relevant, because these can reveal patterns or alternative explanations.

Discuss a focused plan with a GP or dietitian before removing several foods. Reintroduction helps test whether the suspected food truly reproduces symptoms, while nutrition advice reduces the chance of missing protein, vitamins, minerals or energy.

Call emergency services for breathing difficulty, throat or tongue swelling, collapse, severe dizziness or rapidly worsening symptoms after food, as these can signal a serious allergic reaction rather than intolerance.

Arrange prompt assessment for blood in the stool, persistent vomiting, dehydration, trouble swallowing, fever, unexplained weight loss, anaemia or symptoms that wake you repeatedly. These findings warrant evaluation for causes beyond food intolerance.

Ask what mechanism the proposed test measures, how its result would change management, whether allergy or coeliac disease needs assessment first, and how to reintroduce foods safely.