Oral Allergy Syndrome


Oral Allergy SyndromeThe Oral Allergy Syndrome is the most common food-related allergy in adults.  In actuality, the oral allergy syndrome is not a direct food allergy. Rather it represents cross-reactivity between distant remnants of tree or weed pollen still found in certain fruits and vegetables.  Therefore, the oral allergy syndrome is only seen in those allergic to tree and weed pollen. The oral allergy syndrome is commonly called oral allergy or mouth allergy by those who suffer from this aggravating condition. Fortunately, symptoms of the oral allergies are generally mild and transitory, and rarely does it progress to a severe systemic allergic reaction such as anaphylaxis.

Oral Allergy Syndrome Symptoms

Oral allergy syndrome symptoms are classically itching of the throat, mouth, and tongue. The itchiness of the throat commonly results in the patient trying to relieve this symptom by rubbing the tongue against the soft palate making a characteristic “clucking” sound.  These symptoms present within several minutes of ingestion of uncooked fruits and vegetables. Symptoms are almost always localized to the upper oral tract. Lip swelling can occasionally occur.The vast majority of patients experience symptoms within five minutes of ingestion.  Depending on the time of year, the presentation can be affected by the particular pollen season.

Oral Allergy Syndrome Causes

Oral allergy symptoms result from ingestion of fruit or vegetable proteins that cross-react with antibodies of tree or weed pollen proteins. It should be emphasized that this is not a direct allergy to the fruit or vegetable, but rather a reaction to the tree or weed pollen with which it cross-reacts. Therefore, allergy testing to the fruit or vegetable itself rarely yields a positive result. Testing to its corresponding pollen however, will be highly positive.

Who is Affected by Oral Allergy Syndrome?

By definition, persons with oral allergy syndrome have allergy to either tree or weed pollens. The oral allergy syndrome can occur in individuals allergic to any tree or any weed species. Studies suggest that 25%-75% of pollen allergic individuals will have oral allergy symptoms. Both children and adults can be affected by the oral allergy syndrome.

Foods That Cause Oral Allergy Syndrome

Essentially, any raw fruit or vegetable can potentially elicit symptoms in tree or weed allergic individuals. However, this has been described most often with the following:

  • Birch tree pollen allergy may cause symptoms upon the ingestion of apple, pear, apricot, and almond and, to to a lesser extent with celery, carrot, hazelnut, soy, and peanut.
  • Birch pollen allergic patients have also been observed to have cross-reactivity to latex, grass, olive tree, and mugwort pollen.
  • Mugwort pollen may cause symptoms upon the ingestion to celery,  and to a lesser extent with mustard, anise, coriander, cumin, fennel, and parsley.
  • Celery attributed symptoms are also seen in areas where birch is prevalent as well, as there is a high degree of cross reactivity.
  • Ragweed allergy commonly causes symptoms upon the ingestion of foods in the gourd melon family members such as watermelon, cantaloupe, honeydew, zucchini, and cucumber, as well as with banana.
  • There are also reports with peach, plantain, and saffron. This is not limited to just ragweed, but can include other weed family members.


It is also important to mention a related entity, the Latex-Fruit Syndrome, which operates under very similar circumstances.  Latex is tree derived and its primary allergen shares similarities with fruit proteins.  Latex is an ubiquitous allergen in our environment, and there is high degree of contact in day to day activities.

The following food proteins have demonstrated cross reactivity with latex proteins:

  • melon
  • banana
  • avocado
  • chestnut
  • kiwi
  • potato
  • bell pepper
  • mango
  • papaya
  • passion fruit
  • tomato
  • celery

Oral Allergy Syndrome Treatment

The treatment strategy for any food allergy, including the oral allergy syndrome, is avoidance.  This condition is limited to ingestion of only uncooked fruits or vegetables.Cooked fruits and vegetables are generally well tolerated, as the heating process breaks down the allergenic proteins.

Antihistamines are generally very effective in reducing or eliminating the throat itching that occurs with ingestion. An allergist may recommended that individuals with oral allergy syndrome carry an EpiPenĀ® or another epinephrine auto-injector for the rare occasion whereby a more serious reaction would occur. Anaphylaxis is very rare with the oral allergy syndrome. Immunotherapy, or desensitization, is not indicated for the treatment of oral allergy symptoms, although some patients on immunotherapy which includes the relevant allergens may see some improvement in oral allergy syndrome symptoms.



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