Common allergy tests: what to know

A skin prick test places tiny amounts of suspected allergens on the skin, usually the forearm or back, then checks for a local reaction. A blood test measures allergy-related antibodies to selected substances. Neither test should be interpreted in isolation: a positive result can show sensitivity without proving that the substance causes every symptom, while a negative result may not answer every clinical question.

Testing may be considered for recurring nose or eye symptoms, suspected [Food Allergy](/conditions/food-allergy/), asthma linked with exposures, or reactions to dust mites and pets. Conditions such as [Allergic Rhinitis](/conditions/allergic-rhinitis/) and [Allergic Conjunctivitis](/conditions/allergic-conjunctivitis/) are diagnosed using the symptom pattern as well as any test result.

Bring a symptom diary describing timing, foods, medicines, environments, exercise, and the reaction itself. Include photos of skin changes if they disappear before the appointment. Tell the clinician about medicines, pregnancy, skin conditions, previous reactions, and any breathing symptoms. Some medicines can affect skin testing, so do not stop prescribed treatment without specific advice.

Testing should be targeted rather than a broad search for every possible trigger. The result is most useful when it answers a clear question and guides avoidance, treatment, or further evaluation.

Seek emergency help immediately for sudden breathing difficulty, throat or tongue swelling, faintness, or widespread symptoms after a suspected exposure; this may be [Anaphylaxis](/conditions/anaphylaxis/). Testing is not a substitute for urgent treatment. Arrange routine review for repeated reactions, unexplained wheezing, persistent sinus symptoms, or symptoms affecting sleep and daily activities.

What reaction are we trying to investigate? Which test is suitable for me? Should I pause any medicine before testing? How will a positive or negative result change my plan? Do I need an allergy specialist?