Allergies can affect what you eat, products you use, and even the way you breathe. When allergies combine with a breathing condition called asthma, it’s called allergic asthma. Allergic asthma is a condition where your airways tighten when you breathe in an allergen. This can be something in the air — often pollen, dander or mold spores. Allergens are also called triggers because they set off your asthma. Things that could cause you to have a reaction, might not affect other people.

When you have allergies your body creates a response to something it thinks is a threat — the allergen. It fires up all of its defenses to try and fight off danger. This is done by your immune system. Your immune system typically works to protect you from disease. When your immune system thinks that there’s danger, it releases a chemical called immunoglobulin E (IgE). This substance is meant to fight back and protect your body. However, high amounts of IgE can cause your airways to tighten, making it difficult to breathe.