What are the other Names for this Condition? (Also known as/Synonyms)

• Pollen-Food Syndrome

What is Oral Allergy Syndrome? (Definition/Background Information)

• Oral Allergy Syndrome is an allergic condition that manifests as an abnormal immune reaction/response of the mouth and throat on eating certain specific raw fruits and vegetables such as orange, melon, pear, tomato, and cucumber, among others. The condition may also occur from eating nuts such as walnuts, peanuts, and almonds
• Oral Allergy Syndrome is often associated with pollen allergy, and so the condition is also known as Pollen-Food Syndrome. The allergic reaction noted may include swollen mouth parts, runny nose, throat pain, nausea, and rarely, breathing difficulties. In some individuals, Oral Allergy Syndrome may lead to an anaphylactic shock, which is a medical emergency
• In majority of cases, the condition is mild, and the symptoms may last for only about 1-2 hours. If necessary, an antihistamine oral medication may be administered. The prognosis of individuals with Oral Allergy Syndrome is typically excellent

Who gets Oral Allergy Syndrome? (Age and Sex Distribution)

• Oral Allergy Syndrome is normally seen in older children and adults; unlike food allergy, this condition is uncommon in babies and young children
• Both males and females are affected, and no gender preference is noted
• Worldwide, there is no racial or ethnic preference observed

What are the Risk Factors for Oral Allergy Syndrome? (Predisposing Factors)

The risk factors for Oral Allergy Syndrome include:

• Individuals with any form of pollen allergy have a higher risk for developing Oral Allergy Syndrome
• Any family history of allergies may put one at a higher risk for developing the condition
• Having one form of allergy may place one at risk for other allergy forms
• Consuming raw fruits and vegetables

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Oral Allergy Syndrome? (Etiology)

An allergic reaction occurs in an individual with Oral Allergy Syndrome because the immune system recognizes certain compounds/proteins in the raw plant foods as being dangerous and harmful to the body. However, consuming cooked plant products is not known to result in this allergic syndrome.

• Intake of the food (protein) results in the production of antibodies, specifically immunoglobulin E (IgE). The next time the individual is exposed to the particular food, the antibodies that are circulating in blood causes an antibody-antigen reaction
• The antibody-antigen reaction results in the production of histamine and other chemical messengers, which cause the symptoms seen during an allergic reaction. The quantity of food that triggers an allergy need not be significantly large

However, it is unclear why individuals with specific forms of pollen allergies are more at risk for Oral Allergy Syndrome on consuming specific plant foods. According to medical literature, the following is noted:

• Individuals with grass pollen allergy are known to be allergic to potato, kiwifruit, tomato, and peanuts
• Individuals with ragweed pollen allergy are known to be allergic to sunflower seeds, banana, and cucumber
• Individuals with birch pollen allergy are known to be allergic to apple, nuts (such as almond, walnut, and hazelnut), carrot, pear, coriander (seeds of the cilantro plant), plum, peas, and beans

What are the Signs and Symptoms of Oral Allergy Syndrome?

The signs and symptoms of Oral Allergy Syndrome are usually short-term and may include:

• Redness and swollen mouth parts and throat; itching of the oral cavity is common
• Runny nose and eyes
• Throat pain
• Feeling nauseous
• Puffed-up eyes
• In particular, the throat, mouth, tongue, lips, eyes, and ears may be affected
• The onset of signs and symptoms may be seen immediately on eating the allergic food; or later, even after an hour
• In many individuals, the signs and symptoms do not exceed an hour or so

Generally, not all episodes of allergy will be of the same severity. A severe allergic reaction (anaphylaxis) is a medical emergency. It may be noted occasionally.

How is Oral Allergy Syndrome Diagnosed?

A diagnosis of Oral Allergy Syndrome may involve the following exams and procedures:

• Physical examination, assessment of symptoms, and medical history evaluation (history of allergies in the family)
• Food diary: Once an allergy is suspected, the healthcare provider may request to maintain a food diary, to note what is being consumed on a regular basis and the corresponding symptoms observed. The healthcare provider can help check which food products are causing allergies through a process of elimination

The following tests may be conducted to diagnose Oral Allergy Syndrome:

• Oral food challenge testing: When the individual is administered the allergens in a controlled manner to check for symptoms that develop
• Radioallergosorbent (RAS) test; to determine the specific allergy-causing substance
• Skin-prick test:
  • For this test, tiny amounts of certain substances are injected right underneath the skin (forearm, upper arm, or back)
  • After 15-20 minutes, if the spot where the chemical was injected swells, or if there is redness noticed, then it indicates that the individual may be allergic to the substance
• Blood test to detect antibodies (IgE antibody test)

A differential diagnosis is important to exclude other conditions that present similar signs and symptoms. These may include:

• Allergic contact dermatitis
• Anaphylaxis
• Angioedema
• Contact cheilitis
• Contact stomatitis 
• Contact urticaria
• Eosinophilic esophagitis
• Gastroesophageal reflux disease (GERD)
• Lip licker's dermatitis
• Oral lichen planus

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Oral Allergy Syndrome?

The complication of Oral Allergy Syndrome is associated with the allergic reaction itself and it depends on the severity of the reaction. In a vast majority of cases, no significant complications are noted. The possible complications include:

• Breathing difficulties if the condition is severe
• Anaphylactic shock that may be life-threatening
• Having one form of allergy can make the individual vulnerable to other allergy forms
• In severe allergic reactions, a tracheostomy may have to be performed to enable oxygen delivery to the lungs
• Recurrence of the condition
• Treatment complications

How is Oral Allergy Syndrome Treated?

In most cases, the condition is mild and no significant treatment measures are needed since the symptoms are known to subside quickly (usually in an hour). Washing or rinsing the mouth repeatedly with water and taking oral antihistamine medication may be sufficient treatment.

In general, the treatment measures available for Oral Allergy Syndrome include:

• Avoiding consumption of specific raw plant foods and food products; elimination diets supervised by a qualified dietitian
• Anti-allergic medication for mild reactions; antihistamine therapy, which is prescribed by the allergist
• Symptomatic treatment; use of decongestants, especially for nose block including steroid sprays
• In the case of anaphylaxis (severe allergic reaction), epinephrine or adrenaline is immediately administered
• Breathing support, as necessary, to control asthma symptoms and low blood pressure
• Immunotherapy, in case of severe allergies, for long-term tolerance development

Regular follow up visits with the healthcare provider is important and recommended.

How can Oral Allergy Syndrome be Prevented?

Oral Allergy Syndrome may be prevented by considering the following steps:

• Avoid consuming raw the specific plant food item that one is allergic to. Ensure that the specific allergic food item is well-cooked prior to consumption
• Check ingredients of food before using; educate oneself on foods that potentially contain the allergic substance
• Parents must be watchful and read food labels, to ensure they do not inadvertently give their child such foods
• Appropriate maternal diet during pregnancy can help build stronger resistance (against allergies) in children
• While eating out, explain the specific food allergies to the hotel/restaurant service staff, in order to ensure that the food is without the substances one is allergic to

What is the Prognosis of Oral Allergy Syndrome? (Outcomes/Resolutions)

• The prognosis of Oral Allergy Syndrome depends on the severity of the signs and symptoms, but is generally excellent with appropriate treatment in a vast majority of individuals
• In some cases, the allergic reaction may be severe, causing anaphylaxis. This is a medical emergency that can lead to a respiratory failure. It requires an immediate treatment of the condition. In such cases, the prognosis may be unpredictable, and depends on whether immediate medical assistance is provided or was delayed

Additional and Relevant Useful Information for Oral Allergy Syndrome:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/