(MayoClinic.com) You may wonder what allergies and asthma have in common besides a maddening ability to make you miserable. A lot, as it turns out. Allergies and asthma often occur together. In fact, allergic asthma (allergy-induced asthma) is the most common type of asthma in the United States.

If you have both allergies and asthma, the same substances that trigger your allergy symptoms can also inflame your airways, leading to asthma symptoms such as shortness of breath, wheezing and chest tightness.

For many people with asthma, their asthma symptoms are triggered by an allergy to airborne substances such as pollen, dust mites or pet dander. In some people, skin or food allergies can cause asthma symptoms.

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

An allergic response affects the lining of the nose and the lining of the airways in a similar way. Symptoms occur when antibodies in your blood are exposed to an allergy-causing substance (allergen). These antibodies can trigger allergy symptoms such as nasal congestion, scratchy eyes or a skin reaction — and for many, inflammation of the airways associated with asthma.

For example, if your immune system produces allergy antibodies when you're exposed to cats, you're said to have a cat allergy. Proteins in cat fur or cat dander trigger the release of chemicals that cause inflammation and swelling in the lining of the nose. If you have allergic asthma, your reaction to cat fur or dander can also cause the lower airways to become inflamed, triggering asthma symptoms.

Some allergy treatments can reduce asthma symptoms. A type of allergy treatment called allergy shots (immunotherapy) can help treat asthma by gradually reducing your immune system response to allergens that cause your asthma symptoms.

If you have allergic asthma, avoiding the allergic substances that trigger your symptoms can reduce asthma and in some cases, control it completely.

Some medications work for both allergies and asthma, but may be taken differently. For example, corticosteroids which you spray into your nose reduce inflammation from hay fever. Corticosteroid creams applied to your skin reduce inflammation by an allergic skin reaction. And inhaled corticosteroids, which you breathe into your lungs using an inhaler device, reduce inflammation of the bronchial tubes caused by asthma.

Taken in pill form, montelukast (Singulair) is used to help with symptoms caused by both allergies and asthma. Called a leukotriene modifier, this medication helps regulate the immune system chemicals released during an allergic reaction.

Certain other medications are clearly more effective for one condition over another. Antihistamines, for example, are commonly used to treat hay fever but don't work well in treating asthma. Bronchodilator inhalers, which open congested airways, are a big part of asthma treatment, though they aren't used to treat hay fever.

A family history of allergies is a major risk factor for allergic asthma. Another risk factor is having hay fever or other allergies. More than one out of every four people who have hay fever also develops asthma.

Though allergic asthma is the most common form of asthma, there are other forms and triggers of asthma, including exercise-induced asthma and nonallergic asthma triggered by infections or cold air or gastroesophageal reflux disease (GERD). Some people have asthma triggered by more than one type of trigger.

If you have bothersome allergy and asthma symptoms, talk to your doctor about treatment. Recognizing the relationship between the body's immune system and how the airways react has led to improved treatment of asthma symptoms for many people.

Knowing your triggers, taking steps to avoid them, and working with your doctor to find the right treatment to manage your symptoms will help keep both your allergy and asthma symptoms under control.

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