I have a burning sensation in my mouth. How can I tell whether I am having an allergic reaction?

Burning in mouth. People that are allergic to airborne pollens often experience burning or itching in their mouth after eating a fruit or vegetable distantly related. This "oral allergy syndrome" is common and constitutes a local reaction rather than a severe problem. Patients with significant food allergies may experience mouth symptoms but often also experience digestive/skin/respiratory problems.
It is difficult. In my experience a burning sensation in the mouth is probably not do to an allergy such as we see in hayfever allergy but can be related to a variety of conditions including infectious and nutritional in addition to sensitivities.