Allergy tolerance tests: what to expect

Depending on the suspected trigger, a clinician may use a skin-prick test, a blood test for allergen-specific antibodies, or a supervised challenge. A positive result shows sensitisation; it does not by itself prove that normal exposure causes symptoms.

Skin-prick testing places small amounts of selected allergens on the skin and checks for a local raised reaction. Blood testing can be useful when skin testing is unsuitable. Neither method measures how severe a future reaction might be.

The term tolerance test can also refer to a medically supervised exposure, often called a challenge. This is different from trying the suspected food or medicine at home. The clinician chooses the test from your reaction pattern, timing, exposures and current health.

Bring a list of suspected triggers, what happened after exposure, how quickly symptoms began, medicines taken and any photographs of rashes. Tell the clinic about asthma, pregnancy, previous severe reactions and all medicines or supplements.

Some antihistamines can affect skin-test results, but do not stop prescribed medicine unless the testing clinic gives specific instructions. After testing, follow the clinician's exposure or avoidance plan rather than removing many foods without guidance, because broad restriction can make nutrition harder to manage.

Call emergency services for trouble breathing, throat or tongue swelling, a hoarse voice, faintness, collapse, confusion, or rapidly worsening symptoms affecting more than one body system. Use prescribed adrenaline immediately according to your action plan, then seek emergency care even if symptoms improve.

Arrange a routine review when reactions recur, the trigger is unclear, symptoms interfere with eating or breathing, or asthma becomes harder to control. Testing should take place in a setting equipped for the type of reaction being assessed.

Ask which suspected allergens are worth testing, whether your medicines affect the chosen method, what a positive or negative result changes, and whether you need an emergency action plan. If a challenge is proposed, ask where it will occur, how you should prepare and what observation is needed afterward.