U.S. National Library of Medicine
What is asthma?
Asthma is a chronic (long-term) lung disease. It affects your airways, the tubes that carry air in and out of your lungs. When you have asthma, your airways can become inflamed and narrowed. This can cause wheezing, coughing, and tightness in your chest. When these symptoms get worse than usual, it is called an asthma attack or flare-up.
What causes asthma?
The exact cause of asthma is unknown. Genetics and your environment likely play a role in who gets asthma.
An asthma attack can happen when you are exposed to an asthma trigger. An asthma trigger is something that can set off or worsen your asthma symptoms. Different triggers can cause different types of asthma:
- Allergic asthma is caused by allergens. Allergens are substances that cause an allergic reaction. They can include
- Dust mites
- Pollen from grass, trees, and weeds
- Waste from pests such as cockroaches and mice
- Nonallergic asthma is caused by triggers that are not allergens, such as
- Occupational asthma is caused by breathing in chemicals or industrial dusts at work
- Exercise-induced asthma happens during physical exercise, especially when the air is dry
Asthma triggers may be different for each person and can change over time.
Who is at risk for asthma?
Asthma affects people of all ages, but it often starts during childhood. Certain factors can raise your risk of having asthma:
- Being exposed to secondhand smoke when your mother is pregnant with you or when you are a small child
- Being exposed to certain substances at work, such as chemical irritants or industrial dusts
- Genetics and family history. You are more likely to have asthma if one of your parents has it, especially if it's your mother.
- Race or ethnicity. Black and African Americans and Puerto Ricans are at higher risk of asthma than people of other races or ethnicities.
- Having other diseases or conditions such as obesity and allergies
- Often having viral respiratory infections as a young child
- Sex. In children, asthma is more common in boys. In teens and adults, it is more common in women.
What are the symptoms of asthma?
The symptoms of asthma include:
- Chest tightness
- Coughing, especially at night or early morning
- Shortness of breath
- Wheezing, which causes a whistling sound when you breathe out
These symptoms can range from mild to severe. You may have them every day or only once in a while.
When you are having an asthma attack, your symptoms get much worse. The attacks may come on gradually or suddenly. Sometimes they can be life-threatening. They are more common in people who have severe asthma. If you are having asthma attacks, you may need a change in your treatment.
How is asthma diagnosed?
Your health care provider may use many tools to diagnose asthma:
- Physical exam
- Medical history
- Lung function tests, including spirometry, to test how well your lungs work
- Tests to measure how your airways react to specific exposures. During this test, you inhale different concentrations of allergens or medicines that may tighten the muscles in your airways. Spirometry is done before and after the test.
- Peak expiratory flow (PEF) tests to measure how fast you can blow air out using maximum effort
- Fractional exhaled nitric oxide (FeNO) tests to measure levels of nitric oxide in your breath when you breathe out. High levels of nitric oxide may mean that your lungs are inflamed.
- Allergy skin or blood tests, if you have a history of allergies. These tests check which allergens cause a reaction from your immune system.
What are the treatments for asthma?
If you have asthma, you will work with your health care provider to create a treatment plan. The plan will include ways to manage your asthma symptoms and prevent asthma attacks. It will include:
- Strategies to avoid triggers. For example, if tobacco smoke is a trigger for you, you should not smoke or allow other people to smoke in your home or car.
- Short-term relief medicines, also called quick-relief medicines. They help prevent symptoms or relieve symptoms during an asthma attack. They include an inhaler to carry with you all the time. It may also include other types of medicines which work quickly to help open your airways.
- Control medicines. You take them every day to help prevent symptoms. They work by reducing airway inflammation and preventing narrowing of the airways.
If you have a severe attack and the short-term relief medicines do not work, you will need emergency care.
Your provider may adjust your treatment until asthma symptoms are controlled.
Sometimes asthma is severe and cannot be controlled with other treatments. If you are an adult with uncontrolled asthma, in some cases your provider might suggest bronchial thermoplasty. This is a procedure that uses heat to shrink the smooth muscle in the lungs. Shrinking the muscle reduces your airway's ability to tighten and allows you to breathe more easily. The procedure has some risks, so it's important to discuss them with your provider.
What is chronic bronchitis?
Chronic bronchitis is a type of COPD (chronic obstructive pulmonary disease). COPD is a group of lung diseases that make it hard to breathe and get worse over time. The other main type of COPD is emphysema. Most people with COPD have both emphysema and chronic bronchitis, but how severe each type is can be different from person to person.
Chronic bronchitis is inflammation (swelling) and irritation of the bronchial tubes. These tubes are the airways that carry air to and from the air sacs in your lungs. The irritation of the tubes causes mucus to build up. This mucus and the swelling of the tubes make it harder for your lungs to move oxygen in and carbon dioxide out of your body.
What causes chronic bronchitis?
The cause of chronic bronchitis is usually long-term exposure to irritants that damage your lungs and airways. In the United States, cigarette smoke is the main cause. Pipe, cigar, and other types of tobacco smoke can also cause chronic bronchitis, especially if you inhale them.
Exposure to other inhaled irritants can contribute to chronic bronchitis. These include secondhand smoke, air pollution, and chemical fumes or dusts from the environment or workplace.
Rarely, a genetic condition called alpha-1 antitrypsin deficiency can play a role in causing chronic bronchitis.
Who is at risk for chronic bronchitis?
The risk factors for chronic bronchitis include:
- Smoking. This the main risk factor. Up to 75% of people who have chronic bronchitis smoke or used to smoke.
- Long-term exposure to other lung irritants, such as secondhand smoke, air pollution, and chemical fumes and dusts from the environment or workplace.
- Age. Most people who have chronic bronchitis are at least 40 years old when their symptoms begin.
- Genetics. This includes alpha-1 antitrypsin deficiency, which is a genetic condition. Also, smokers who get chronic bronchitis are more likely to get it if they have a family history of COPD.
What are the symptoms of chronic bronchitis?
At first, you may have no symptoms or only mild symptoms. As the disease gets worse, your symptoms usually become more severe. They can include:
- Frequent coughing or a cough that produces a lot mucus
- A whistling or squeaky sound when you breathe
- Shortness of breath, especially with physical activity
- Tightness in your chest
Some people with chronic bronchitis get frequent respiratory infections such as colds and the flu. In severe cases, chronic bronchitis can cause weight loss, weakness in your lower muscles, and swelling in your ankles, feet, or legs.
How is chronic bronchitis diagnosed?
Your health care provider may use many tools to make a diagnosis:
- A medical history, which includes asking about your symptoms
- A family history
- Various tests, such as lung function tests, a chest x-ray or CT scan, and blood tests
What are the treatments for chronic bronchitis?
There is no cure for chronic bronchitis. However, treatments can help with symptoms, slow the progress of the disease, and improve your ability to stay active. There are also treatments to prevent or treat complications of the disease. Treatments include:
- Lifestyle changes, such as
- Quitting smoking if you are a smoker. This is the most important step you can take to treat chronic bronchitis.
- Avoiding secondhand smoke and places where you might breathe in other lung irritants
- Ask your health care provider for an eating plan that will meet your nutritional needs. Also ask about how much physical activity you can do. Physical activity can strengthen the muscles that help you breathe and improve your overall wellness.
- Medicines, such as
- Bronchodilators, which relax the muscles around your airways. This helps open your airways and makes breathing easier. Most bronchodilators are taken through an inhaler. In more severe cases, the inhaler may also contain steroids to reduce inflammation.
- Vaccines for the flu and pneumococcal pneumonia, since people with chronic bronchitis are at higher risk for serious problems from these diseases.
- Antibiotics if you get a bacterial or viral lung infection
- Oxygen therapy, if you have severe chronic bronchitis and low levels of oxygen in your blood. Oxygen therapy can help you breathe better. You may need extra oxygen all the time or only at certain times.
- Pulmonary rehabilitation, which is a program that helps improve the well-being of people who have chronic breathing problems. It may include
- An exercise program
- Disease management training
- Nutritional counseling
- Psychological counseling
- A lung transplant, as a last resort for people who have severe symptoms that have not gotten better with medicines
If you have chronic bronchitis, it's important to know when and where to get help for your symptoms. You should get emergency care if you have severe symptoms, such as trouble catching your breath or talking. Call your health care provider if your symptoms are getting worse or if you have signs of an infection, such as a fever.
Can chronic bronchitis be prevented?
Since smoking causes most cases of chronic bronchitis, the best way to prevent it is to not smoke. It's also important to try to avoid lung irritants such as secondhand smoke, air pollution, chemical fumes, and dusts.
NIH: National Heart, Lung, and Blood Institute