Is a banana allergy common and how do you test for it?

No: Banana allergy is not that common. Make an appointment with you allergists. After the obtain a history and perform a physical exam they may suggest skin testing with a commercial reagent and / or they may use a fresh piece of banana. Alternatively they may order a blood test. If there is a degree of suspicious for banana allergy and the testing does not help a food challenge may be done.

Think latex: Banana allergy is not very common. Recent development of reactions to banana when you've eaten bananas for years without problems suggest cross-reactivity with latex and a potentially dangerous latex allergy. Discuss this with your primary care physician or consult a board-certified allergist.