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What are Allergies?

An allergy is when your body’s immune system reacts to something that’s normally harmless to most people. If you come into contact with a substance that your immune system views as a threat, it responds by releasing a chemical called histamine. The release of histamine, along with other substances released by the body, is what causes the allergic reaction. Where you experience the reaction depends on where histamine was released in your body. For example, if you’re allergic to something you inhale—like pollen, dust mites, animal dander or mold—your nose, lungs and eyes could be where you’ll have symptoms. If you’re allergic to any food, you may experience symptoms in your mouth, stomach or intestines. In most cases, it’s not so easy to trace a symptom back to its cause.

Experience the reaction

About Allergy Symptoms

Allergy symptoms can range from mild—like sneezing and watery eyes—to severe – like anaphylaxis, a rare but serious, life-threatening allergic reaction. Mild and more common allergy symptoms include: 

  • Sneezing
  • Watery eyes
  • Runny nose
  • Wheezing
  • Coughing
  • Stomach pain

Symptoms can easily be confused with other conditions like an everyday cold, flu or celiac disease. And it gets more complicated because your allergies—and symptoms—can change over time and with age.

Recognizing the typical symptoms or signs of allergies is the first step toward an accurate diagnosis, appropriate management and optimal symptom relief. Learn more below about common symptoms and the allergies that may be the cause.

common allergy symptoms, signs, and causes






Why don’t I have ALLERGY symptoms all of the time?

Everyone has their own unique combination of allergic triggers and not all of them are obvious. You may experience mild reactions to several things, but they are so small that you don’t notice them on their own. But when you encounter multiple things you are allergic to at the same time, all of those small reactions can add up to the point where you start having allergy symptoms.1,2 Determining your allergic triggers can help you stay below the point where you start experiencing symptoms – your symptom threshold. Learn more about how your allergic triggers can add up to symptoms.

    Symptom threshold     

Allergy Season
Am I Allergic?

Am I allergic?

You may think what you’re experiencing is normal, but so many people are used to living with their symptoms that they never consider asking for help. So, how do you know if your symptoms are caused by an allergy or not? A simple blood test—together with your medical history—can help identify underlying allergen triggers, if you have an allergy. Knowing if you’re allergic and what you’re allergic to can help you, or a loved one, avoid or minimize symptoms. Be sure to consult with your healthcare professional.

Get answers

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  1. Wickman M. When allergies complicate allergies. Allergy. 2005;60(Suppl 79):14–18.
  2. Burbach GJ, et al. GA2 LEN skin test study II: clinical relevance of inhalant allergen sensitizations in Europe. Allergy. 2009;64:1507-15.