Symptoms and diagnosis

Photo of a man coughing and holding his chest

In people with , the airways are overly sensitive. This chronic disease typically comes in episodes or "attacks" of wheezing, coughing and shortness of breath. These symptoms could also be signs of other diseases, though. So before starting with treatment, it's important to find out what exactly is causing the breathing problems.

The mucous membranes lining the airways of people with chronic are constantly on stand-by, ready to trigger an inflammatory response. This means that certain triggers can set off a very rapid and very intense reaction. Compared to people who have healthy lungs, their mucous membranes are red and swollen, and more blood flows through them. The cells in the membranes produce thick and sticky mucus. If an trigger is present too, the muscles surrounding the walls of the airways tighten as well. Together, all of these factors cause the (lung airway passages) to become narrow and prevent air from flowing freely in and out of the lungs. This leads to shortness of breath.

A severe attack feels a bit like trying to breathe only through a straw for a few minutes. Even if you suck air out of it and blow air into it as hard as you can, you are unable to get enough air into and out of your lungs.

What are the typical symptoms of asthma?

During an attack, breathing out is usually more difficult than breathing in. If the gets worse, a whistling or rattling sound known as "wheezing" may be heard while breathing out. The person might have to cough or feel the urge to cough a lot.

During an attack, breathing difficulties, coughing or wheezing that is only minor at first can worsen and develop into more serious shortness of breath. Because it becomes more and more difficult to breathe out, it also becomes difficult to breathe in. Worsening shortness of breath is often associated with chest tightness – a situation that can be frightening.

Being frightened can make the symptoms even worse. Seeing your child, or someone else you are close to, gasping for breath is an alarming experience and difficult to cope with.

But the situation only becomes dangerous if the labored and exhausting breathing leads to a lack of oxygen. This can usually be avoided by using effective medication.

How severe is the asthma?

Asthma symptoms can range from an occasional, slight urge to cough to extreme shortness of breath during an attack. Asthma used to be classified into four general severity categories, mostly depending on how frequent and how severe the symptoms were. Nowadays, symptoms tend to be assessed based on how effectively they are being managed. According to this approach, there are three levels of severity: controlled, partly controlled, and uncontrolled .

This classification is based on factors such as

  • how many times a week someone has symptoms during the day,
  • how much their daily activities are affected by the ,
  • whether they also have symptoms at night, and
  • how much the affects their lung function.

The frequency of acute episodes (flare-ups or exacerbations) with shortness of breath, wheezing, coughing and chest tightness is also taken into account.

How is asthma diagnosed?

Asthma, or a tendency to have attacks, is often already diagnosed in childhood or puberty. Diagnosing young children is difficult, though. This is because they often have colds or , which cause very similar symptoms to when it first starts developing. All of these illnesses are associated with coughing or slight wheezing. Asthma-like symptoms in bronchitis tend to become less common as children get older, though. In children, chronic (long-lasting) is often associated with an . Other typical signs of are usually not yet present.

It often takes some time before people who have , or the parents of a child with , go to see a doctor. By that point they have usually already been concerned for quite a while. Once the cause of the breathing difficulties has been clarified, though, it's possible to start treatment. In , this means relieving symptoms as well as preventing attacks.

The main tools for diagnosing are an in-depth talk with the doctor (anamnesis), a physical examination and lung function tests (peak flow measurement and/or spirometry). Further tests may be needed in order to be absolutely sure of the .

What do the talk with the doctor and the physical examination involve?

Asthma is diagnosed based on an in-depth talk with a doctor (anamnesis) followed by a physical examination. The symptoms associated with can also be signs of other health problems, so when you describe your symptoms to the doctor, it's important to tell him or her everything you have observed and experienced related to the symptoms. This includes worries and concerns, as well as ways that the symptoms affect everyday life. Any of these clues may help to track down the cause.

In order to get a clearer picture, your doctor will ask you a number of questions, such as

  • what symptoms occur and when,
  • under what conditions they go away,
  • whether you have any other illnesses, especially allergies,
  • whether you frequently had coughs or wheezing as a child,
  • whether anyone in your family has or any allergies,
  • whether you are taking medication and, if so, which medication.
  • whether you are exposed to specific substances (fumes, smoke or sprays) at home or at work, and
  • whether you have any particular physical or emotional problems.

In the physical examination the doctor will then check your general health as well as the function of your lungs, heart and circulation. This is also done to rule out any other illnesses.

How is your lung function tested?

Lung function tests can tell us how well our lungs are performing. If someone has , it's important to know whether inhaled air can flow freely through their airways or whether their breathing is obstructed by narrow . This can usually be done using two tests known as spirometry and peak flow measurement.

In spirometry (“measuring of breath”), both the amount of air you breathe out and how fast you blow it out are measured. Here you blow hard into the mouthpiece of the device, called a spirometer. This measures the amount of air that you exhale in one second when blowing as hard as you can. Doctors call this the “forced expiratory volume in 1 second” (FEV1). The test can usually be done by your family doctor, and can also be used to monitor the progression of the illness: By comparing old and new spirometry readings, you can see whether your lung function has improved or worsened over time.

Peak flow measurement is an important lung function test that you can carry out on your own at home. The measuring device, known as a “peak flow meter,” is easy to use. After taking a deep breath, you blow into it as hard as you can. This measures how fast you can blow air out of your lungs. The peak flow reading indicates whether the are narrowed.

Why may further tests be needed?

Asthma symptoms can vary a lot over time. Even if you have , your doctor may not find any signs of when checking your lung function for the first time. Nearly all of the tests measure how narrow your are. But if you happen to be symptom-free when the test is done, your will be almost normal too. People who smoke, are overweight, or generally unfit may also have typical symptoms like shortness of breath, despite not having . To make sure you get an accurate result, the following things may be done after the first reading:

  • You may be given a substance which causes the airways of people with to temporarily become narrower (bronchial provocation test).
  • You may be asked to get on a treadmill or an exercise bike. In people with , the lung function reading is often worse following vigorous physical activity (exercise test).
  • You may be given an inhaler to open your airways. If your lung capacity improves after using the inhaler, it is a sign that you have (reversibility test).

Lung x-rays or blood tests are generally only used if the symptoms and findings aren't very typical of , and the doctor would like to rule out another disease. This is because the breathing difficulties could also be caused by other illnesses such as or chronic obstructive .

When does it make sense to have an allergy test?

Asthma is diagnosed using the tools and tests described above. Other tests, like blood tests or provocation tests, can be used to find out whether the is a reaction to substances that trigger allergies (allergens). Provocation tests are done in a doctor's office to look at whether a particular allergen triggers attacks.

Allergens are often triggers for as well, but not always. First you have to find out whether you are even prone to allergies. Only then can you start trying to find out what is causing the , for example using special skin tests. But if a skin test causes an allergic reaction, it doesn't necessarily mean that you have .

It's important to let your doctor know if you have noticed any patterns related to when, and in what situations, your symptoms arise. For instance, do you have them on sunny days in early summer, in cold winter air, in the morning or evening, at home or at work, after having certain kinds of food or drink, after touching pets or when cleaning your home? This information could help to find out whether a certain allergen is causing the symptoms.

Bundesärztekammer (BÄK), Kassenärztliche Bundesvereinigung (KBV), Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF). Nationale Versorgungsleitlinie: Asthma. AWMF-Registernr.: nvl-002. 2020.

Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention (Update). 2021.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Updated on July 20, 2022

Next planned update: 2025


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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