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Oral allergy syndrome

Oral allergy syndrome
Do you get an itchy throat or swollen lips when you eat certain foods? You could be suffering from oral allergy syndrome. In this post, I’ll be discussing what causes it and more.

I have decided to write this as an additional post to my hayfever, diet and exercise post, being a sufferer of OAS myself and knowing that it affects a very high number of hayfever sufferers.

What is oral allergy syndrome and what causes it?

OAS also known as pollen food syndrome is an allergic reaction to protein in certain plant foods. The protein is seen in a similar way to pollen in the air and as such is closely related to a hayfever sufferers allergic reaction where the immune system over reacts and mistakes it as a harmful bacteria. Therefore it tends to affect those that have allergic reactions mainly to tree pollen (birch pollen), but can also affect those with grass/weed related hayfever and is therefore also known as cross-reactivity.

As a side note. If you suffer from an itchy mouth/ throat in the evening, it is possible this can be caused by dusty dry air in your bedroom and not just a reaction from food you have eaten.

What are the symptoms of oral allergy syndrome?

Usually you will feel OAS in or around the mouth and it usually will last for a short period until the protein is broken down my your saliva, usually within an hour, but often just a few minutes. It can be worse at the time of your hayfever period as your body is already reacting to the pollen in the air. OAS symptoms are normally mild and include:

  • Itchy roof of mouth (soft palate)
  • Itchy throat
  • Tingling sensation in the mouth (tongue)
  • Itchy ears
  • Possibly sometimes: sneezing or runny nose, itchy eyes, itchy nose, swollen red lips

Other allergies may cause similar symptoms, such as latex and brewer’s yeast allergies, so it may be worth checking with your doctor just in case.

Severe reactions, such as rashes, stomach cramps, vomiting, diarrhoea, wheezing, breathing difficulties, increased heart rate, anaphylaxis and extreme swelling needs to be seen by a medical professional/doctor, as this may indicate a direct allergic reaction to the foods you have just eaten rather than OAS and a direct allergic reaction could be life threatening, such as in the case of a nut or seafood allergy for example.

What foods can cause oral allergy syndrome?

The following are some of the most common foods to cause a reaction and they are mainly made up of raw plant based foods with a protein make-up similar to that found in trees.

  • Almonds
  • Apples
  • Apricots
  • Bananas
  • Brazil nuts
  • Cantaloupe
  • Carrots
  • Cashew nuts
  • Celery
  • Cherries
  • Cucumbers
  • Hazelnuts
  • Honeydew
  • Kiwi
  • Mango
  • Melon
  • Oranges (various types)
  • Pea
  • Peaches
  • Peanuts
  • Pears
  • Peppers
  • Plums
  • Potatoes
  • Some herbs and spices
  • Soy milk
  • Strawberry
  • Tomatoes
  • Watermelon
  • Wheat

What can you do about oral allergy syndrome?

One thing you could do is cook (bake, steam, poach or microwave) your food, yes as much as I believe raw foods can give you great health benefits, the cooking of the foods that affect you means you can breakdown and change the structure of the proteins. This stops the immune system reacting to it as a pollen. However for some people it is possible to still get a reaction, therefore if you suffer from a reaction after cooking the foods it may be best to avoid that food altogether.

Some raw foods could be substituted with canned fruits/vegetables, but be aware of their sugar/salt content.

You could also try peeling some foods, as most of the protein can be found in the skin and you may find it can be enough to stop your reaction to that food.

Don’t consume large amounts of the foods that can cause the reaction, such as creating smoothies loaded with raw vegetables or fruit or a plate full of various nuts for example.

Also, use hayfever medication such as an antihistamine to help reduce histamine production.

Another thing you need to do is avoid processed/junk food as these are unhealthy and won’t improve your health or immune system. A healthy immune system can help reduce the reaction and symptoms associated with it.

Catch 22: some foods contain quercetin that helps fight allergies, but they are also often the ones that have the plant protein, so you may have to work out which ones cause you an issue and which one’s don’t.


There isn’t really much to summarize, other than either recognise foods that cause you issues and take steps to reduce or avoid their effect on you or get professional advice if in doubt about the causes of your reaction to the foods you consume.