Allergies and asthma: They often occur together

James T C Li, M.D., Ph.D.

You may wonder what allergies and asthma have in common besides making you miserable. A lot, as it turns out. Many people who have allergies also have asthma.

The same substances that trigger your hay fever symptoms may cause asthma symptoms. These include pollen, dust mites and pet dander. In some people, skin or food allergies can cause asthma symptoms. This is called allergic asthma.

James T C Li, M.D., Ph.D., a Mayo Clinic allergy specialist, answers questions about the link between allergies and asthma.

How does an allergic reaction cause asthma symptoms?

An allergic response happens when immune system proteins called antibodies mistakenly identify a harmless substance, such as tree pollen, as an invader. To protect your body from the substance, antibodies bind to the allergen.

The immune system releases chemicals that lead to allergy symptoms. Common symptoms are nasal congestion, runny nose, itchy eyes or skin reactions. For some people, this same reaction also affects the lungs and airways, leading to asthma symptoms.

Are allergies and asthma treated differently?

Most treatments are designed to treat either asthma or hay fever, also called allergic rhinitis. But a few treatments help with both conditions. Some examples:

• Leukotriene modifier. This type of medicine can ease both allergic rhinitis and asthma symptoms. Called a leukotriene modifier, this daily pill helps control immune system chemicals released during an allergic reaction. Montelukast (Singulair) is the leukotriene modifier that can treat both asthma and allergic rhinitis.

• Allergy shots, also called immunotherapy. Allergy shots can help treat asthma. They gradually reduce your immune system response to certain allergy triggers. This treatment involves getting regular shots. The shots have a tiny amount of the allergens that trigger your symptoms.

  Your immune system builds up a tolerance to the allergens over time, and your allergic reactions diminish. In turn, asthma symptoms also decrease.

• Anti-immunoglobulin E (IgE) therapy. When you have an allergy, your immune system mistakenly identifies a specific substance as something harmful. Then your body releases antibodies, called IgE, against the culprit allergen.

  The next time you come across that allergen, the IgE antibodies sense it. They signal your immune system to release histamine and other chemicals into your bloodstream.

  A type of medicine called a biologic can help. It affects the action of IgE in the body and helps prevent the allergic reaction that triggers asthma symptoms. Omalizumab (Xolair) is a biologic used to treat allergic asthma. This treatment is used for more severe allergic asthma, but it also might help allergic rhinitis.

You may need other medicines to treat allergies or asthma, especially if your symptoms become worse at times. But recognizing and avoiding the substances that trigger your symptoms is an important step you can take.

Who’s at risk of allergic asthma?

A family history of allergies is a major risk factor for allergic asthma. If you have hay fever or other allergies yourself, your risk of getting asthma is higher.

Is all asthma caused by allergies?

Though allergic asthma is very common, there are other types of asthma with different kinds of triggers. For some people, asthma triggers are exercise, infections, cold air, gastroesophageal reflux disease or stress. Many people have more than one kind of asthma trigger.

Take charge: Get symptoms under control

Know the things that trigger your allergy and asthma symptoms and learn how to limit your exposure to them. Work with a healthcare professional to find the best treatment to manage your symptoms, and check in with your healthcare team regularly.

Because allergy and asthma symptoms can change over time, you may need to adjust your treatment. Learn the signs that your asthma may be flaring up — and know what to do when it does.