Symptoms of asthma can be mild or severe. You may have no symptoms; severe, daily symptoms; or something in between. How often you have symptoms can also change. Symptoms of asthma may include:

• Wheezing, which is a whistling noise of varying loudness that occurs when the airways of the lungs (bronchial tubes) narrow.
• Coughing, which is the only symptom for some people.
• Chest tightness.
• Shortness of breath, which is rapid, shallow breathing or difficulty breathing.
• Sleep disturbance because of coughing or having a hard time breathing.
• Tiring quickly during exercise.

An asthma attack occurs when your symptoms suddenly increase. Factors that can lead to an asthma attack or make it worse include:

• Having a cold or another type of respiratory illness, especially one caused by a virus, such as influenza.
• Exercising (exercise-induced asthma), especially if the air is cold and dry.
• Exposure to triggers, such as cigarette smoke, air pollution, dust mites, or animal dander.
• Being around chemicals or other substances at work (occupational asthma).
• Changes in hormones, such as during the start of a woman's menstrual blood flow or pregnancy.
• Taking medicines, such as aspirin (aspirin-induced asthma) or nonsteroidal anti-inflammatory drugs.

Many people have symptoms that become worse at night (nocturnal asthma). In all people, lung function changes throughout the day and night. In people with asthma, this often is very noticeable, especially at night, and nighttime cough and shortness of breath frequently occur. In general, waking at night because of shortness of breath or cough indicates poorly controlled asthma.

Symptoms are used to classify asthma by severity. They are also used along with peak expiratory flow to help define the green, yellow, and red zones of your asthma action plan. You use this plan to decide on treatment during an asthma attack.

Other conditions with symptoms similar to asthma include heart failure, chronic obstructive pulmonary disease (COPD), and vocal cord dysfunction.