If after one bite you experience a weird tingling sensation in your mouth that you've never had before you could, like many people in the UK, be suffering from an Oral Allergy Symptom.

Oral Allergy Syndrome, or the more commonly named Pollen Food Syndrome, can cause swelling in the mouth or throat with symptoms lasting up to an hour.

[Read more: Could you spot the signs of a severe allergic reaction?]

The majority of suffers are most likely to already have hay fever, but they are not the only people who can be affected by this not-so-well-known syndrome.

What is Oral Allergy Syndrome?

Head of Clinical Services at Allergy UK, Amena Warner says: “Oral Allergy Syndrome was originally the name given to a set of oral symptoms that arise from a ‘cross reactivity’ with birch pollen.

Now it is more widely recognised that other pollens from grass and weeds as well as trees can cause these same symptoms, which is why it is now termed Pollen Food Syndrome (PFS).

It is becoming increasingly more common and we are seeing children displaying these symptoms as well as adults.”

What causes Pollen Food Syndrome?

PFS is caused by proteins found in the likes of fresh fruit, raw vegetables, nuts and spices, which have a similar structure to the type found in pollen from trees, grasses or weeds.

The most common pollen found in PFS is birch tree pollen as it contains the allergen Bet v 1, which is highly cross-reactive to a wide range of plant foods.

The reason PFS is most common with hay fever suffers is down to the immune system confusing the similar proteins, identifying the protein as pollen and causing the individual to have an allergic reaction.

Although people with hay fever may not initially suffer from Pollen Food Syndrome, just as people without can.

Common foods associated with PFS

The most common foods known to cause, but not limited to, Pollen Food Syndrome are:

- apples
- peaches
- kiwi
- hazelnuts
- almonds

[Read more: Can you cope with a life-threatening allergy attack?]

Symptoms of PFS

If affected, sufferers are likely to experience symptoms within a matter of minutes after consumption, specifically within the mouth and throat.

The most common symptoms are:

- mild itching
- swelling (lips, tongue mouth or throat)
- itchy eyes or inside the nose
- tingling or itching sensation

More severe cases may include:

- nausea
- vomiting
- feeling light-headed
- breathing difficulties

What to do if you have a reaction or think you may suffer from PFS

If you begin showing signs of a reaction, the first step would be to rinse your mouth out with water or have a hot drink in order to stop any remaining allergens from activating.

Depending on the severity, symptoms should settle down within the 30 minutes to an hour.

People who suffer more severe symptoms should seek medical help immediately and describe it as an anaphylactic shock.

Antihistamine is also seen as a good temporary source of treatment, if the case is severe.

If you think you might suffer from Pollen Food Syndrome, speak to your GP, who may then refer you to an consultant allergist where details of reactions are listed and a prick test will be carried out.