April 10, 2025 | Black & Kletz Allergy
Pollen food allergy syndrome (PFAS), also known as oral allergy syndrome, is a condition in which there is first a “sensitization” of the immune system to various pollens and subsequent “reactions” when exposed to these pollens. Secondly, there is a similarity of the protein allergens in the pollen and the protein allergens of certain raw or fresh fruits and/or vegetables. The individual’s immune system, which has been previously sensitized to pollen, will also react to the similarly structured proteins in the raw or fresh fruits and/or vegetables. As a result, when a person who has a pollen allergy (usually trees and/or weeds) eats certain raw or fresh fruits and/or vegetables, that individual’s immune system “thinks” that it is being exposed to pollen proteins when in fact it is being exposed to fruit and/or vegetable proteins that have a very similar chemical structure to the pollen proteins. The body in turn reacts to the fresh fruit and/or vegetable proteins in a similar fashion as a typical allergic reaction but is usually more localized to where the food makes direct contact, such as the lips, tongue, palate, ears, gums, and/or throat. Essentially, there is a cross-reaction to the fresh fruit and/or vegetable because that food is mistaken for pollen and thus reacts in a similar way except the reaction is mostly where contact occurs between the food and the mouth. Note that if the fruit or vegetable is cooked, the pollen food allergy reaction does not usually take place because the heating of the fruit and/or vegetable denatures the protein resulting in the immune system not recognizing this denatured protein anymore because the altered structure of the protein does not look like the pollen protein (allergen) anymore.
The symptoms experienced by the individual who has pollen food allergy syndrome typically includes itching of the lips, tongue, palate, ears, gums, and/or throat after eating raw fresh fruits and/or vegetables. Swelling of the lips, tongue, and uvula, as well as a tightness of the throat feeling may occur in some individuals. Very rarely, a more severe allergic reaction such as hives, generalized itching, wheezing, shortness of breath, drop in blood pressure, and/or anaphylaxis can occur. In these patients, a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) or intranasal epinephrine device (e.g., Neffy) is prescribed and individuals are told to go to the closest emergency room if the self-injectable epinephrine device or epinephrine nasal spray is used. It should be noted that certain nuts in certain individuals may also cause pollen food allergy syndrome symptoms. However, it must be stressed that most nut allergy reactions are not a result of pollen food allergy syndrome but rather a true IgE-mediated Type I allergic reaction which may result in a reaction that is severe and even life-threatening.
About 33% of people who have seasonal allergic rhinitis (i.e., hay fever) have pollen food allergy syndrome. In adults, close to 55% of all food allergic reactions are due to a cross-reaction between a food and a pollen. Luckily however, the reaction experienced by most individuals who have pollen food allergy syndrome is minor and self-limited. The symptoms of pollen food allergy syndrome usually occur within minutes of ingesting the food. In pollen food allergy syndrome, in general, once the allergen reaches the stomach, it is broken down by the stomach acid, and the allergic reaction does not progress further. Although the symptoms can occur at any time during the year, pollen food allergy syndrome symptoms most often occur during the corresponding pollen season. The allergenic proteins associated with pollen food allergy syndrome are usually destroyed by cooking the food. As a result, most reactions in patients with pollen food allergy syndrome are caused by eating “raw” or “fresh” fruits and/ or vegetables. The main exceptions to this are celery and nuts, which may cause reactions even after being cooked.
Certain pollens are more likely to cross-react with certain raw or fresh fruits, vegetables, and/or nuts. The list below demonstrates the cross-reactivity that may occur between common pollens and raw or fresh fruits, vegetables, and/or nuts:
- Alder pollen: Apples, cherries, peaches, pears, almonds, celery, hazelnuts, parsley
- Birch pollen: Apples, avocados, apricots, carrots, bananas, cherries, figs, nectarines, kiwis, peaches, pears, plums, prunes, strawberries, almonds, hazelnuts, peanuts, coriander, celery, chicory, fennel, potatoes, parsley, parsnips, peppers, wheat, soy
- Grass pollen: Tomatoes, oranges, melons, figs
- Mugwort pollen (i.e., celery-mugwort-spice-syndrome)
: Celery, carrots, fennel, coriander, parsley, peppers, sunflower - Ragweed pollen: Melons (e.g., honeydew, cantaloupe, watermelon), bananas, artichokes, cucumbers, zucchini, Echinacea, dandelions, chamomile tea, hibiscus tea
Note: All of the above pollens may also cross-react with berries (e.g., strawberries, blueberries, raspberries), citrus fruits (e.g., oranges, lemons), watermelon, mangos, peanuts, figs, grapes, pomegranates, and/or pineapple.
In addition to the above, there are 3 syndromes that associated with pollens and foods:
Latex-fruit syndrome — About 30-50% of people who are allergic to natural rubber latex have an accompanying hypersensitivity to some plant-derived foods, especially fresh fruits. Several fruits and vegetables (e.g., bananas, avocados, kiwis, chestnuts, melons, celery, apples, carrots, tomatoes, white potatoes) have been linked with this syndrome.
Celery-mugwort-birch-spice syndrome — The celery-mugwort-birch-spice syndrome is essentially a severe form of celery allergy seen in adults and children who are sensitized to both mugwort and birch pollens. Affected individuals react to celeriac (i.e., the root of the celery plant or celery tuber).
Mugwort-mustard allergy syndrome — Individuals sensitized to mugwort pollen may develop a systemic food allergy reaction to mustard.
Diagnosis: The diagnosis of pollen food allergy syndrome begins after the allergist performs a comprehensive history and physical examination which is consistent with the symptoms of pollen food allergy syndrome. Allergy prick skin testing, food elimination, and oral food challenges may also be beneficial in helping to establish the diagnosis. Food prick skin testing with fresh foods is more dependable than using commercially-prepared food extracts because the process of making the extract can destroy the responsible protein allergen.
Treatment: The management of pollen food allergy syndrome involves avoiding exposure to the involved raw or fresh fruits, vegetables, and/or nuts in order to prevent the itching feeling in the mouth and throat, as well as to reduce the risk of rare systemic symptoms. Using oral antihistamines can lessen the severity of symptoms that may occur, however systemic reactions require treatment with epinephrine devices. Individuals with a history of a systemic reaction should be prescribed a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) or an epinephrine nasal spray (e.g., Neffy) and instructed on when and how to use the device. It is important that an individual go immediately to the closest emergency room once an epinephrine device is used.
Some studies have demonstrated that treating pollen allergies with allergy immunotherapy (i.e., allergy shots, allergy injections, allergy hyposensitization) can reduce the symptoms associated with cross-reacting fruits and vegetables that cause pollen food allergy syndrome.
The board certified allergists at Black and Kletz Allergy have over 50 years of experience in diagnosing and treating food allergies. We treat both pediatric and adult patients. Black & Kletz Allergy has 3 convenient locations with on-site parking located in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. The Washington, DC and McLean, VA offices are Metro accessible and we offer a free shuttle that runs between the McLean, VA office and the Spring Hill metro station on the silver line. To schedule an appointment, please call any of our offices or you may click Request an Appointment and we will respond within 24 hours by the next business day. We have been servicing the greater Washington, DC metropolitan area for many decades and we look forward to providing you with the utmost state-of-the-art allergy care in a friendly and pleasant environment.
