Symptoms, diagnosis, treatment and more

Most people are familiar with hay fever and food allergies, but many don’t realize there may be a connection. Many people with hay fever also experience allergic symptoms in or around the mouth after eating certain raw fruits and vegetables, including watermelon. This type of reaction is known as pollen food allergy syndrome or oral allergy syndrome (AOS).

Technically, a watermelon allergy is OAS, which is different from a food allergy. Unlike a food allergy, VS symptoms are not caused by food protein. Instead, ODS is caused by pollen allergens that cross-react with certain plant foods, triggering an allergic reaction from the immune system.

This article explains the symptoms, diagnosis, and treatment of watermelon allergy. It also covers risk factors for developing a watermelon allergy and foods to avoid if you develop OAS.

Watermelon Allergy Symptoms

Unlike food allergies, which can cause many systemic (body-wide) symptoms, watermelon allergy caused by OAS usually only produces localized itching. Symptoms of OAS include:

  • Itchy mouth
  • Sore throat
  • Swelling of the lips, mouth, tongue and throat

People with OAS usually only experience a reaction when eating raw fruits or vegetables, because cooking changes the proteins involved. These symptoms usually start immediately after putting the watermelon in your mouth and go away soon after swallowing it.


Although rare with OAS, anaphylaxis, a serious and life-threatening allergic reaction, can occur with any allergy. So, if you experience any of the following anaphylaxis symptoms, get medical help right away:

  • Urticaria
  • Swelling
  • Wheezing
  • Unconsciousness
  • Chest tightness
  • Difficulty breathing
  • Hoarseness
  • Difficulty swallowing
  • Vomiting
  • Diarrhea
  • stomach cramps
  • Rinsing
  • A sense of impending doom

How is watermelon allergy diagnosed?

A careful history can usually provide enough clues to a health care provider that OAS may be the culprit. However, certain diagnostic tools can help them confirm their suspicions.

Allergy testing may include:

  • Skin test, where an allergist (an allergy specialist) scratches your skin with an allergen and then watches for a reaction
  • Blood test, where a lab technician evaluates your blood for IgE antibodies
  • Oral food challenge, where you consume suspicious foods and document any reactions

If you do not test positive for a specific food allergy, but you test positive for grass or ragweed pollen, an allergist can diagnose a watermelon allergy.

Watermelon Allergy Risk Factors

A ragweed allergy is associated with OAS reactions to watermelons. Although anyone can develop OAS, the condition is less common in young children.

What causes watermelon allergy?

Certain foods correlate with particular environmental allergens. For example, if you are allergic to various types of melons, you may also suffer from allergic rhinitis (nasal allergies) caused by ragweed pollen.

Symptoms of VS are your body’s reaction to proteins in the fruit that resemble those in pollen. This cross-reactivity confuses the immune system, resulting in symptoms of OAS.

Other common correlations are as follows.

  • Birch pollen: apple, almond, carrot, celery, cherry, hazelnut, kiwi, peach, pear, plum
  • Grass pollen: celery, melons, oranges, peaches, tomatoes
  • Ambrosia pollen: banana, cucumber, melons, sunflower seeds, zucchini

Although the above associations are possible, they do not exist in every individual. For example, a person allergic to birch pollen may have apple OAS but not react to the other foods mentioned. Similarly, a person may have a ragweed pollen allergy and only notice oral symptoms with melons.

Watermelon allergy in children and babies

Although less common in young children, older children, teens, and young adults can suddenly develop VS even after years of eating watermelon without any problems.

A 2015 study published in the International dental journal assessed the prevalence of OAS in children. In 120 children with seasonal allergic rhinitis, OAS symptoms were most pronounced in those who were allergic to birch.

In addition, ODS was more common in adolescents than in older children and more common in people with allergic rhinitis and asthma, as well as allergic rhinitis and eczema.

to sum up

The most important risk factor for watermelon allergy is an allergy to pollen, especially grass and ragweed. OEA is more common in adults, but children can also develop OEA. It is more common in adolescents than in young children.

Watermelon Allergy Treatments

Since the symptoms are mild and fade quickly, treatment is usually not necessary.

How to Treat an Allergic Reaction to Watermelon

If you ever have a severe allergic reaction, a healthcare professional will likely prescribe you an EpiPen.

An EpiPen is a synthetic form of epinephrine hormone that you inject when you experience anaphylaxis. It can stop the allergic reaction and give you time to seek emergency medical attention.

When to See a Health Care Provider

If you have symptoms of VS, it’s a good idea to make an appointment with an allergist or your primary health care provider for a diagnosis. Also, if you experience symptoms of anaphylaxis, such as difficulty breathing, swelling, or hives, seek emergency medical attention immediately.

Foods to Avoid

If you have a watermelon allergy caused by OAS, you should avoid consuming watermelon. In addition to whole watermelon, keep an eye out for watermelon in salads, drinks, and smoothies.

People with OAS often have reactions to more than one food. So, if you are allergic to ragweed, you may also react when you eat these foods:

  • Banana
  • cantilope
  • Chamomile
  • Cucumber
  • Echinacea
  • Honeydew
  • Sun-flower seeds
  • Zucchini

If you notice a reaction to other foods, add them to your list of foods to avoid.


Oral allergy syndrome causes an allergy to watermelon. This happens when you have a pollen allergy that cross-reacts with specific proteins in certain fruits and vegetables, including watermelon.

Symptoms are immediate and localized and include itching and tingling in the mouth and throat. Symptoms go away quickly, usually on swallowing. Rarely, anaphylaxis may occur. Treatment is to avoid offending foods and use an EpiPen for severe reactions.

A word from Verywell

If you have seasonal allergic rhinitis, you are at increased risk for ODS. However, not everyone with a pollen allergy develops ODS. Remember that OAS can occur even after eating watermelon without a problem for a lifetime. So if you suddenly develop symptoms, seek a diagnosis. This way, you will have a clear idea of ​​how to handle the situation in the future.

Frequently Asked Questions

  • What’s in watermelon that makes you allergic?

    When you have a watermelon allergy, your body actually mistakes melon proteins for pollen-like proteins. This confusion of the immune system is known as “cross-reactivity”.

  • What is pollen and food allergy syndrome?

    Pollen and food allergy syndrome (PFAS) is another term for oral allergy syndrome (OAS). This means that when you have a pollen allergy, the proteins in certain plant foods can resemble those of pollen and disrupt your immune system, leading to localized VS symptoms like itching when you eat certain foods.

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