I ate a piece of avocado today, and my ears and throat were itchy shortly thereafter. i have eaten avocado in the past with no problem. could i suddenly be allergic?

Yes: Yes. You may have become sensitized from previous exposure.

Complex: Yes you can develop sensitivity to a certain agent after years of exposure, avocado cross reacts with other agents in the environment such as latex, so double exposure can enhance development of allergies, you probably want to avoid avocados, keep an antihistaminic handy if you have a reaction, if any other allergy problem check aaaai.org or acaai.org for an allergist in your area,

Might be allergic.: Food allergy carries the risk of anaphylactic shock; can be life-threatening and needs epinephrine immediately. ER visits for this rose sharply in US last 5 yrs. However, some fresh fruits and vegetables cause local mouth itch/burn only in some who are allergic to pollen. Avacado can do this, but don't assume it-important to know the difference. See an allergist.

Possibly allergic: avoid avocado for 1 week and then eat and see if you get symptoms. If you don't get symptoms then your throat itching was from something else. Throat itching associated with a food could be a marker for angioedema to develop at a later date. Angioedema is a severe life threatening reaction. At any sign of throat closing or difficulty breathing seek immediate medical attention

Yes: Although this may just be from oral allergy syndrome, you should consult an allergist before attempting to eat avocado again. Do you have latex allergy also?