Pollen-food cross-reactivity
If you are allergic to pollen, you may have noticed that certain foods cause an uncomfortable sensation in your mouth. That is oral allergy syndrome (OAS) - the most common form of cross-reactivity between pollen and food.
What is oral allergy syndrome?
Oral allergy syndrome (OAS) occurs when the immune system reacts to similarities between proteins in pollen and proteins in certain foods. It most often affects people who are already allergic to tree, grass or weed pollen.
Typical OAS symptoms include:
- Itching or tingling of the lips, tongue, throat or palate
- Mild swelling of the lips or tongue
- Redness or irritation around the mouth
- An uncomfortable sensation in the ears (rare)
Symptoms usually appear within a few minutes of eating fresh food and tend to fade quickly. It is worth noting that cooking often destroys the proteins that trigger the reaction, so many people can eat a cooked version of the same food without any problem.
Important note
This information is for general guidance and does not replace medical advice. If you suspect an allergic reaction or experience serious symptoms (difficulty breathing, throat swelling, anaphylaxis), seek medical help immediately. For the diagnosis and treatment of allergies, see an allergist or immunologist.
Cross-reactivity by pollen type
Select the pollen you are allergic to in order to see the list of foods that may trigger reactions:
Hazel (Corylus)
We have no recorded food cross-reactions for this allergen.
Alder (Alnus)
Alder belongs to the same family (Betulaceae) as birch and shares similar proteins. Cross-reactivity is most pronounced with stone fruit and some nuts. Symptoms are usually milder than with a birch allergy.
Related allergens: Birch
Fruit
Vegetables
Nuts
Spices
Legend:
Elm (Ulmus)
We have no recorded food cross-reactions for this allergen.
Cypress (Cupressaceae)
We have no recorded food cross-reactions for this allergen.
Ash (Fraxinus)
We have no recorded food cross-reactions for this allergen.
Birch (Betula)
Birch contains the Bet v 1 protein, which is similar to proteins in many fruits and vegetables. This is the most common cause of oral allergy syndrome in Croatia. Symptoms usually include itching and swelling of the lips, tongue and throat after eating fresh fruit.
Related allergens: Alder
Fruit
Vegetables
Nuts
Spices
Legend:
Hornbeam (Carpinus)
We have no recorded food cross-reactions for this allergen.
Oak (Quercus sp.)
We have no recorded food cross-reactions for this allergen.
Holm oak (Quercus ilex)
We have no recorded food cross-reactions for this allergen.
Plane tree (Platanus)
We have no recorded food cross-reactions for this allergen.
Willow (Salix)
We have no recorded food cross-reactions for this allergen.
Walnut (Juglans)
We have no recorded food cross-reactions for this allergen.
Sweet chestnut (Castanea)
We have no recorded food cross-reactions for this allergen.
Pine (Pinus)
We have no recorded food cross-reactions for this allergen.
Olive (Olea europaea)
Olive mainly shows cross-reactivity with other plants from the Oleaceae family (jasmine, ash), but it rarely causes food reactions. Oral allergy syndrome with an olive pollen allergy is extremely rare. People allergic to olive pollen can usually eat olive oil and olives without any problem.
Fruit
Legend:
Grass (Poaceae)
Grasses (Poaceae) can cause cross-reactivity with certain fruits and vegetables, especially those from the gourd family (Cucurbitaceae). Reactions are usually milder and less common than with tree pollen. Grass proteins can also trigger reactions to cereals.
Fruit
Vegetables
Other
Legend:
Plantain (Plantago)
We have no recorded food cross-reactions for this allergen.
Nettle (Urticaceae)
We have no recorded food cross-reactions for this allergen.
Pellitory (Parietaria)
We have no recorded food cross-reactions for this allergen.
Mugwort (Artemisia)
Mugwort is known for causing the "celery-mugwort-spice syndrome". Cross-reactivity is very common with celery, carrot and various spices. People allergic to mugwort often react to several different foods at once. Symptoms can be stronger than with other forms of oral allergy.
Related allergens: Ragweed
Fruit
Vegetables
Spices
Other
Legend:
Ragweed (Ambrosia)
Ragweed belongs to the Asteraceae family and can cause cross-reactions with bananas, melons and watermelon. It is one of the most aggressive allergens, and food reactions can be stronger than with other pollens. Cooking usually does not ease the symptoms the way it does with other allergies.
Related allergens: Mugwort
Fruit
Vegetables
Spices
Other
Legend:
Frequently asked questions
Why can I eat cooked fruit but not fresh fruit?
The proteins that cause oral allergy syndrome are usually heat-labile, meaning they break down at high temperatures. Cooking, baking or heating often destroys these proteins, so cooked food does not trigger a reaction. That is why many people can eat apple pie but not fresh apples.
Are all varieties of a fruit equally problematic?
No. Different varieties of the same fruit can contain different amounts of allergenic protein. For example, some apple varieties (such as Golden Delicious) can cause stronger reactions than others. Experimenting with different varieties can help you find the ones you tolerate better.
Can I develop new allergies over time?
Yes. Cross-reactivity can develop or change over the years. People with a pollen allergy can develop new food sensitivities, especially if pollen exposure increases or the pollen allergy worsens. Keep track of your reactions and talk to your doctor about any changes.
When should I see a doctor?
See an allergist if you experience symptoms beyond mild itching in the mouth, if symptoms get worse, if they affect your quality of life, or if you have any respiratory symptoms (coughing, wheezing). Also, if you are not sure whether it is OAS or a true food allergy, testing can be helpful.
What are protein families and why do they matter?
The proteins that cause allergies are grouped into families based on their structure. For example, the Bet v 1 protein from birch is similar to proteins in apples, cucumbers and celery. That is why an allergy to one type of pollen can trigger reactions to several different foods that contain similar proteins.
Tips for managing cross-reactivity
- 1.Cook your food: Cooking, heating or baking often destroys allergenic proteins and makes the food safe to eat.
- 2.Peel your fruit: Many allergens are concentrated in the fruit's skin. Removing the peel can reduce the reaction.
- 3.Watch the pollen season: OAS symptoms can be stronger during the flowering season of the pollen you are allergic to.
- 4.Keep a diary: Write down which foods cause reactions and when, so you can spot patterns.
- 5.Consult an allergist: A specialist can confirm the diagnosis, recommend immunotherapy or prescribe medication if needed.
Personalize your pollen forecast
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The information on this page is based on scientific studies of cross-reactivity and oral allergy syndrome, including research published in journals such as Allergy, the Journal of Allergy and Clinical Immunology and Clinical & Experimental Allergy. The data is adapted for allergens present in Croatia.