Oral allergy syndrome is an allergic reaction to food that directly affects the mouth, lips, tongue, and throat. It is synonymous with allergic rhinitis, better known as hay fever. Some fresh fruits, nuts, and vegetables have proteins similar to pollen structure. Eating these can give you an oral allergy syndrome, and can cause an allergic reaction in the mouth and throat.

In other words, the body confuses the protein of the fruit with the protein of the pollen. Specific immunoglobulin E antibodies in the immune system trigger allergic reactions. For this reason, the disorder is often referred to as pollen-fruit allergy syndrome. Since these foods are commonly available throughout the year, oral allergy syndrome is not seasonal.

OAS Food Trigger List 

Proteins are present in all organic matter. The immune system detects unique proteins to target bacteria, viruses, and other unwanted germs. 

However, regular proteins, such as pollen, are often classified as harmful as well.

Oral Allergy Syndrome
Oral Allergy Syndrome

These proteins are available in large quantities after they are ingested or inhaled, and the immune system detects them as abnormal. The body responds with a severe immune response, leading to swelling, various other allergy symptoms, and pain.

Experts claim that more than 60% of all food allergies are likely cross-reactions to pollen allergies. Birch pollen is one of the most common causes of allergic rhinitis. But numerous trees, grasses, and weeds may also cause it.

Different people are allergic to different kinds of food. However, OAS occurs only as a result of cross-reactivity between pollen and some fruits.

Some common food of OAS triggers include:


Herbs and Vegetables

  • Apiaceae family: Celery, carrots, parsley, parsnips, cumin, dill, chervil, and fennel
  • Lettuce
  • Artichokes
  • Cucumbers
  • Peas
  • Carrots
  • Tomatoes
  • Corn
  • Bell peppers
  • Zucchinis
  • Sunflower seed
  • Fresh herbs, such as parsley or coriander

If you have OAS, tree nuts, such as hazelnuts and almonds, can cause your symptoms to flare up. This allergy is milder than those from other nuts, which tend to be fatal. 

Some symptoms of this allergy include

Symptoms of oral allergy syndrome develop soon after consuming specific foods. Symptoms vary considerably and can peak at various stages of life.

Mild signs include

Very severe signs include

  • Swelling in the throat
  • Nausea and vomiting
  • Additional signs can include hives and asthma. Typically, hives occur when the food is sliced, chopped, or scraped.

Diagnosis and Treatment for Oral Allergy Syndrome

Here you can see the diagnosis and treatment for oral allergy syndrome:


The diagnosis of oral allergy syndrome sometimes involves multiple steps. Usually, these include laboratorian processes.

Medical care

Clinical techniques are the most common ones. Diagnosis includes observations of allergic rhinitis along with itching and tingling that occurs after eating fresh fruits or vegetables. In certain cases, an accurate medical history indicates a correlation between eating a particular type of food and the onset of tingling or swelling.

In such cases, an elimination diet may be recommended by the doctor. An individual avoids particular groups of foods that may cause oral allergy syndrome for a given period and records whether there is a difference.

Laboratory tests

Laboratory examinations usually include a skin test, a scratch test, or a blood test. For skin examination, the dermatologist labels the grid on the back or forearm and uses extracts of pollen, fruit, or vegetables. Any marks that form on the skin will be assessed after 15 minutes to analyze the extent of the reaction.

If the prick tests are positive but the food itself does not cause a reaction, a person may be asked to consume a certain amount of suspicious food. The answer immediately after consuming this food will confirm the existence of an oral allergy syndrome.

In certain cases, blood tests may be used to diagnose the disease.


There are no specific remedies for oral allergy syndrome apart from avoiding particular foods associated with allergy symptoms. Careful diet control can ensure that people with the condition can lead normal lives otherwise. 

People with oral allergy syndrome should get proper knowledge of the disorder to help them understand what food is off-limits. In the event of an allergic reaction, the initial treatment normally includes rinsing the mouth with water and then resting. 


Antihistamines normally take 1-2 hours, while the symptoms of oral allergy syndrome generally begin to fade after about 30 minutes. However, an antihistamine can avoid long-lasting effects and therefore should be taken as soon as the reaction takes place.

In certain cases, immune systems can be less susceptible to allergens by immunotherapy or allergy shots. This is particularly useful when a single allergen is involved.

Cooked food

In some cases, cooking foods can kill proteins that cause oral allergy syndrome. However, this depends on the food that causes allergies.

Generally, nuts and spices are exceptions to the cooking norm. Nuts contain several allergens, not all of which are killed by the high temperature. The same is true for celery. Allergens in strawberries are also heat tolerant. Pasteurized fruit juices are usually good as they have been heat-treated.

Processed fruit juices are usually good as they have been heat-treated. Some smoothies may, however, contain raw, unpasteurized juices or purees. This should at best be avoided if any of the ingredients are triggers.

However, most foods are made safe enough by cooking. For instance tomatoes, apples, potatoes, pears, and most soft fruit.

Healthy lifestyle tips

In certain cases, avoiding food completely is the only effective way to prevent signs of oral allergy syndrome. However, there are several approaches that people might want to try so that they can enjoy their favorite food. Microwave fruits – particularly apples – for about 1 minute and then chilled immediately can reduce the effects of oral allergy syndrome to a manageable level. This process can remove the key proteins that trigger reactions.

Also, these proteins are normally high in the skin, so peeling fruit before eating them will greatly minimize reactions. Wearing gloves when peeling fruit can alleviate the risk of hives. Not stir-frying vegetables can also lower the risk of asthma.

People with oral allergy syndrome frequently find that their condition worsening during the pollen season, so they may prefer to avoid triggering foods for the whole season.

Also, controlling seasonal allergic rhinitis is crucial in dealing with symptoms of an oral allergy syndrome. This is usually achieved with antihistamines and a steroid nasal spray 2 weeks before the start of the season, accompanied by daily use during the season.

Also Red; Things To Avoid If You Are Allergic To Water