Avocado allergy can take two different forms: one associated with allergy to tree pollen, such as birch, and another type associated with latex allergy. People with birch-pollen allergy can develop symptoms either immediately or up to 1 hour after eating fresh avocado or an avocado-containing food. Symptoms comprise local reactions in the mouth and throat with itching and inflammation (called oral allergy syndrome, OAS).

Others develop an avocado allergy because of the similarity between the allergens in avocado and natural rubber latex (e.g. gloves, condoms, balloons) a condition known as the latex-fruit syndrome. Symptoms developed by these individuals comprise generalised urticaria, abdominal pain, vomiting and sometimes life-threatening symptoms. These individuals may also develop adverse reactions to chestnut, banana, mango and kiwi.