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Why Is My Mouth So Itchy After Eating Fruit?

by Jack Emerald 4 years ago in health
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You are not alone. Many people suffer from Oral Allergy Syndrome (OAS).

Have you ever eaten a fruit such as an apple, banana, or perhaps a kiwi, and been totally confused as to why your tongue was so itchy? Or maybe your lips and mouth start to swell like Will Smith in Hitch? Perhaps your throat becomes crazy itchy and you have no clue why?

More generally…

Have you ever eaten a raw fruit or vegetable and had an allergic reaction?

You may not have realized it before, but you might have Oral Allergy Syndrome (OAS).

Definition of Oral Allergy Syndrome

A condition that occurs in a subset of those who suffer from intense seasonal allergies. In these people, the consumption of raw fruits and vegetables, and occasionally nuts, initiates an immediate reaction resulting in rapid onset symptoms in the mouth and throat. These symptoms may include itching, swelling, or development of a rash.

A good way to see if you’re prone to OAS is to see if you have already been diagnosed with seasonal allergies in one of the following three categories.

Spring Trees

A notable spring tree pollen is Birch. If you have a Birch allergy, you might have had an allergic reaction to one of the following fruits/nuts:

  • Apple
  • Apricot
  • Carrot
  • Celery
  • Cherry
  • Kiwi
  • Peach
  • Pear
  • Plum
  • Almond
  • Hazelnut

Summer Grasses

Summer grass pollen is a common seasonal allergy that includes Timothy and Orchard grass hay. There are several fruits whose proteins mimic the proteins found in these summer grass pollens:

  • Cantaloupe
  • Honeydew
  • Orange
  • Tomato
  • Watermelon

Fall Weeds

The Ragweed and Mugwort pollens are common causes of allergic reactions during the end of summer and into autumn. Allergists often test these pollens to determine if you have severe fall allergies. The fruits and vegetables listed below have molecular structures that are very similar to fall pollens:

  • Banana
  • Cantaloupe
  • Carrot
  • Celery
  • Cucumber
  • Honeydew
  • Peach
  • Watermelon
  • Zucchini

Symptoms of Oral Allergy Syndrome

Generally, symptoms of OAS manifest almost immediately after eating the offensive food. Symptoms generally begin in the mouth localized to the lips or tongue. After a few minutes, the reaction may spread to the throat. The reaction can be described as a general discomfort or an itchy feeling. Since the throat is connected to the nose and ears via the same cavity, OAS reactions may spread to itchiness in the ears. It is not uncommon for an OAS sufferer to develop a reaction that affects the eyes or nose. A rash may also appear over the throat or on the face.

Where things get a little tricky is when OAS spreads to the gastrointestinal tract. Most commonly, the acids in the stomach break down these fruits and vegetables to the point that the allergens are destroyed. However, in a subset of sufferers, the stomach does not do a good job of denaturation of the fruit and vegetable proteins. If the stomach does not successfully break down the food, then the OAS sufferer will be hit with a second round of reactions. The gastrointestinal reaction may begin with terrible indigestion and escalate to vomiting and diarrhea.

Denaturation of Proteins

Shows the process of how the allergens are broken down.

The proteins in the fruit and vegetables are the main culprit for the allergic reaction. There are certain ways that the proteins can be denatured. The easiest way to change the chemical composition of a fruit or vegetable is to cook it. You might notice that you have an allergic reaction to a raw apple, but never have a problem with apple pie. This is because when you cook the apple, you alter the molecular composition of the fruit. A great way to mitigate the affects of OAS is simply to only consume cooked fruits or vegetables. Keep in mind that jams and preserves are essentially boiled fruit, so these should be an OK option for the OAS sufferer.

You may not be able to eat crudités at your next party, but if you roast these veggies in the oven, you should be good to go.

There are some useful ways to mitigate symptoms.

The number one way to mitigate symptoms was listed above. Avoid, avoid avoid. Do not eat raw fruits or vegetables and you have little to worry about. Here are a few other options.

Peel the fruit.

If you only have really mild symptoms, you may find success in peeling the fruits or vegetables. For some reason, the allergic proteins exists mainly in the skin of these foods. By peeling these fruits you will limit the amount of culprit proteins that you are exposed to.

Frozen Fruits and Vegetables

Freezing fruit also changes the chemical composition, that is why frozen fruit tastes different when compared to fresh fruit. Freezing does not change the composition as much as cooking, but it may do enough to reduce mild symptoms. Give it a try!

What should you do if you accidentally ate a raw fruit or vegetable?

If you only suffer from the first phase of oral allergy symptoms (i.e. those that do not spread to the GI tract), then you can simply take an antihistamine. Common antihistamines include Benadryl, but the generic version works just as well.

Please note that if you already have a nut allergy, you may experience a severe OAS reaction. If this is the case, then you should carry an emergency epinephrine injector. Also known as an EpiPen, epinephrine injectors will save you just in case you slide into anaphylaxis.

Are there any cures for Oral Allergy Syndrome?

I have just outlined how to mitigate the reaction and how to respond to a reaction. We are able to address the symptoms. However, curing the condition is a lot more complicated. As of now, there is no cure to Oral Allergy Syndrome.

Some people have had success with allergy immunotherapy. This can improve the condition and occasionally results in total remission. Allergy immunotherapy is a means by which an allergist exposes you to a tiny amount of the allergen, hoping that you will build up a tolerance over time. This is a very long and expensive process that rarely works.

Going forward, scientists will experiment with gene therapy to see if there is an underlying reason why certain individuals are more susceptible to seasonal allergies.

Latex Allergy

No, not the typesetting program!

Latex is a natural compound that is a type of rubber that can be used to manufacture hospital gloves. The protein in Latex has been found to cause some people to have allergic reactions in the form of rashes when wearing the gloves. The same cross-reactivity to proteins found in different pollens and fruits can be seen with latex and tropical fruits. If you notice that you have OAS symptoms to the following tropical fruits, you may have an allergy to latex:

  • Kiwifruit
  • Passionfruit
  • Cherries
  • Potatoes
  • Paw-Paw
  • Papaya
  • Banana
  • Avocado
  • Fig
  • Peaches
  • Nectarines
  • Plums
  • Tomatoes
  • Celery
  • Chestnuts

What You Should Do If You Think You Have OAS

Photo from National Jewish Health

Definitely go to your physician so that he/she can give you a referral to see an allergist. The allergist will be able to run tests that may include skin pricks or blood samples to determine which allergens and types of pollen you are most allergic to. Your allergist will then be able to help you determine which fruits and vegetables you should stay away from. They will also be able to determine if you have a latex allergy.

If you suffer from OAS, you are not alone, and there are ways to keep your symptoms at ease!


About the author

Jack Emerald

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