For Healthcare Professionals
Welcome! Click here for Healthcare or Laboratory Professional content
Are you a healthcare professional?

The information in this website is intended only for healthcare professionals. By entering this site, you are confirming that you are a healthcare professional.

 Understanding Allergies

An allergy is when your 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, called an allergen, it responds by releasing a chemical called histamine and other substances. The release of these substances is what causes your allergic reaction. Atopy, or having an atopic predisposition, refers to the genetic predisposition to develop allergic diseases.

Sneezing, wheezing and itching - you may think what you’re experiencing is normal. Learn about all the ways your allergies can show up and the common symptoms and triggers associated with them. Recognizing the typical signs is a step towards getting some relief. 

Allergy March Icon

Not everyone with allergies will be considered atopic, and not everyone with atopy develops manifestations of allergic diseases.1

Anaphylaxis Icon

For some, allergic reactions may be serious and in some rare instances, food or an insect sting could result in the life-threatening reaction called anaphylaxis.


Types of allergies & their triggers

Anything from pollen to mold to animals to food can trigger an allergic reaction in someone who is allergic. And while some people may outgrow their existing allergies, new ones could spring up at any time.2 

Certain allergens are frequently responsible for allergic reactions and some include:

Allergy March

Why do we have allergies?

Generally, your immune system protects you from substances that can make you sick. But if you're one whose immune system reacts to something that is harmless to most people, then your body may react with common allergy symptoms such as sneezing, runny nose, and watery eyes. Hundreds of ordinary substances can cause - or trigger - an allergic reaction. Among the most common things that can cause reactions are plant pollen, food, insect stings, mold, dust mites, pet dander, and medications.

Anyone can be affected by allergies, but some people are more prone to them than others. Genetic and environmental factors plat a role in a person's susceptibility to developing allergies. When allergies are common in children, they can occur for  the first time at any age. Some children stop reacting to certain allergens, such as milk and egg, as they grow, but allergies to foods like nuts and fish tend to remain. It's also possible to develop allergies at any age, even as an adult. 


Types of allergies & their triggers

Just about anything you encounter in your environment can trigger an allergic reaction in someone who is allergic. And while some people may outgrow their existing allergies, new ones could spring up at any time.              

The most common allergy causes and triggers include:

  • Animals 
  • Dust mites
  • Insects
  • Mold
  • Tree pollens
  • Grass pollens
  • Weed pollens
  • Egg
  • Milk 
  • Peanut
  • Seafood & shellfish
  • Wheat
  • Soy
  • Tree nuts
  • Fruit & vegetable

These allergens are frequently responsible for allergic reactions. Click on the allergens below to learn more about them:

Question icon

Do You Have Questions?

You’re likely to have questions about allergies. There are so many different types & symptoms associated with them, it can be confusing and may be hard to navigate. Here are answers to some of the most common questions.

Glossary Icon


Sometimes the clinical terms associated with allergies can seem like a foreign language. That’s why we’ve made this easy-to-understand list of terms you may come across when researching your allergies.

  1. Jarvis D, Burney P. The epidemiology of allergic disease. BMJ-Brit Med J. 1998;316: 607-610.
  2. Kamdar T, Peterson S, Lau C, et al. Clinical Communications: Prevalence and characteristics of adult-onset food allergy. J Aller Cl Imm-Pract. 2015;3 (1):114.