Verywell / Zorica Lakonic
Oral allergy syndrome(OAS) is a key in of food allergy.
People with OAS are sensitive to specific types of pollen as well as the foods related to those pollens.
OAS is sometimes also called Pollen Food Allergy Syndrome.
Verywell / Zorica Lakonic
What is Oral Allergy Syndrome?
Most people are familiar withcommon food allergiesto things like peanuts, shellfish, tree nuts, etc.
However, it is also possible to have less common allergies to things likecitrusorcelery.
In many cases, these reactions are resulting from oral allergy syndrome (OAS).
People with OAS have usually already been diagnosed with nasalallergiesto things like tree, weed, or grass pollen.
Some foods contain proteins that are similar in structure to these inhaled allergens.
This causes people with OAS to have food allergy symptoms when they consume those foods.
This is a process known as cross-reactivity.
Symptoms usually appear in the mouth and can occur within five minutes of eating an apple.
For most people, the symptoms will occur within 30 minutes.
Symptoms tend to resolve when you stop eating the apple.
It is also possible to have a more severe reaction, such as throat swelling.
This can cause breathing difficulty.
There is cross-reactivity between different citrus fruits.
This means allergy to one citrus fruit increases the likelihood of allergy to another.
In most cases, they begin within minutes of eating the fruit.
Cross-reactivity with ragweed is known to play a role in allergic reactions to bananas.
Across the globe, spices have become some of the most common food allergens.
Cross-reactivity is commonly due to:
The main symptom is itching in the mouth.
This is extremely rare, however.
Celery
Celery allergies are relatively common.
According to some research, 30% to 40% of allergic individuals are sensitized to celery.
The most common symptoms of a celery allergy include itching and swelling in and around the mouth.
Occasionally, there can be a whole body response, sometimes leading to anaphylaxis.
Coconut is not a tree nut, however.
Most people with a tree nut allergy can safely eat coconut.
Few people have a true coconut allergy, but they do exist.
Symptoms include an itchy mouth and, extremely rarely, anaphylaxis.
Products such as lotions and soaps containing coconut may causecontact dermatitisin some people.
Latex
Latex is produced from the sap of the rubber tree.
The sap contains proteins that are similar to those found in other foods, especially fruit.
In people with this condition, eating these foods can cause allergy symptoms.
Symptoms of Oral Allergy Syndrome
Symptoms of OAS usually appear in the mouth.
It is uncommon for them to appear elsewhere or to progress to anaphylaxis, though it can happen.
Typically, symptoms include:
Symptoms of OAS usually disappear on their own and do not require treatment.
This typically happens as soon as you stop eating the food.
People with OAS have a low risk of anaphylactic shock, but it can happen.
If any of these symptoms occur, seek medical care at once.
How is Oral Allergy Syndrome Diagnosed?
OAS can usually be diagnosed based on your symptoms and medical history.
Your healthcare provider may also want to do a skin prick test or an oral food challenge.
A skin prick test involves introducing an allergen into a small prick on your skin.
If you are allergic, you will develop a reaction at the site.
Either way, you will need to pay close attention to your symptoms.
Usually, these symptoms go away without treatment.
If they progress beyond your mouth, however, they can put you at risk for anaphylaxis.
Talk to your healthcare provider if you’ve ever experienced symptoms after eating one of these potentially cross-reactive foods.
The most effective way to treat a food allergy, including OAS, is by avoiding the trigger.
High temperatures break down the proteins responsible for OAS.
Other strategies are to eat the food in canned form or to peel foods that can be peeled.
This is because the proteins responsible for allergies are often concentrated in the skin.
People may develop allergies to foods they could previously eat without symptoms.
With OAS, the important thing is to avoid those foods that cause symptoms.
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