Allergies don't cause asthma. But people who have allergies (or have family members who have allergies) are more likely to get asthma than those who don't.

And when someone already has asthma, an allergic reaction can sometimes make them have asthma symptoms.

Whatever causes an allergic reaction — like pollen — can also trigger asthma symptoms in some people. But not everyone who has allergies develops asthma. And not all cases of asthma are related to allergies.

How Do Allergies Make Asthma Worse?

Lots of people with asthma find it gets worse when they're around allergens (the things that give them an allergic reaction). Common allergens include dust mites, mold, pollen, and animal dander.

If you have allergies, your immune system reacts to an allergen like it's an unwanted invader. To fight it off, the immune system makes an antibody called immunoglobulin E (IgE). This starts a process where the body releases substances designed to protect it. One of these is histamine. Histamine causes allergic reactions that can affect the eyes, nose, throat, skin, and lungs.

When the airways are affected, it can bring on symptoms of asthma (like coughing, wheezing, or trouble breathing).

The body remembers this reaction. Each time the allergen comes into contact with the body, the same thing can happen. Because of that, allergies can make it hard for some people to keep their asthma under control.

How Do Allergies Affect Asthma?

If you have asthma, your doctor can see if allergies may be causing problems for you. The doctor may suggest a visit to an allergist so you can find out if you're allergic to anything.

If you have allergies, it doesn't mean that they're causing your asthma symptoms. But knowing what they are lets you and your doctor start looking into the connection.

Avoiding possible allergens may be a big help in controlling your asthma. If you can't completely limit your exposure to something you're allergic to, your doctor may recommend medicine or allergy shots.