Asthma

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Asthma causes, triggers, and symptoms

Asthma causes, triggers, and symptoms

Whilst asthma is a prevalent condition nowadays, there are still many misconceptions about how it affects individuals and which individuals it affects. Some believe that asthma is simply a childhood issue to be outgrown, while others falsely think it is a psychological syndrome triggered by stress and anxiety.

However, asthma is a chronic lung condition that all kinds of people from all walks of life can experience in their lifetime, both in childhood and adulthood. But how do you know if you have asthma?

The signs of asthma in adults can vary greatly, and so can the types of asthma. For some, asthma is a nuisance. For others, it can be a daily struggle.

Daniel Atkinson
Medically reviewed by
Daniel Atkinson, GP Clinical Lead
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Medically reviewed by
Dr Daniel Atkinson
GP Clinical Lead
on May 20, 2025.
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Daniel

Last updated on May 20, 2025.

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What is Asthma?

Asthma is a long-term (chronic) condition of the lungs causing hypersensitivity in the airways and resulting in various symptoms, such as shortness of breath or wheezing.

With asthma, the tubes carrying air in and out of the lungs can become inflamed and constricted. This is what causes the telltale chest tightness and breathlessness of an asthma attack.

Asthma is one of the most common conditions affecting children and also commonly affects many adults. In fact, a 2019 report found that over 260 million people have asthma worldwide. That’s nearly four times the entire population of the UK .

What is asthma caused by?

So, how do you get asthma? Truthfully, the exact causes behind asthma remain largely unknown. Sorry, that’s not very helpful, we know.

Of course, there are countless theories around various asthma causes. Genetics and environmental factors, such as pollution, have been suggested as potential factors in the development of asthma .

There are even studies theorising that modern standards of cleanliness play a part in the development of asthma . According to the “hygiene hypothesis”, being too clean prevents the lungs from “learning” how to defend against allergens.

But don’t stop washing your hands just yet. There is currently not enough scientific evidence to definitively prove any of these theories. That said, we do know a lot more about the things that cause asthma symptoms.

Asthma symptoms

Symptoms of asthma vary greatly depending on the individual, so it’s worth knowing the different signs if you believe you might be asthmatic.

  • Coughing
  • Shortness of breath or chest tightness
  • Mucus production
  • Wheezing

Coughing

Does asthma make you cough? It is not usually a common symptom, but a cough can occur if asthma is not adequately managed. Asthma cough symptoms usually include a dry, irritating cough that is persistent or keeps coming back. However, you can also experience an asthma productive cough, which produces thick, clear mucus. This type of cough is generally a symptom of uncontrolled asthma.

What triggers coughing when you have asthma?

It is important to know what triggers asthma coughing and flare-ups in order to avoid the occurrence of an asthma attack. Asthma triggers include:
  • Outdoor allergens (pollen)
  • Indoor allergens (dust, pet hair) Certain drugs
  • Environmental irritants (pollution, smoke)
  • A cold or flu
  • Weather conditions (cold, humidity, changing seasons)
  • Stress
  • Exercise (however, asthma should not prevent you from engaging in physical activity)
If your asthma is flaring up more than twice a week, it could be a sign that your asthma is uncontrolled, and you could seek the help of a specialist.

Why is coughing worse at night if you have asthma?

Many asthma symptoms, and in particular coughing, can worsen during the nighttime hours. The exact reason why symptoms are exacerbated during nighttime is unknown. Still, certain studies theorise that a reclining position, colder temperatures, or hormonal changes during sleep could contribute to an asthma cough at night . That said, worsening asthma symptoms during the night are usually an indication that your asthma is not adequately managed or controlled. Uncontrolled asthma can result in other health problems and complications. Therefore it’s best to consult your GP or an asthma specialist if you are experiencing an increase in your asthma symptoms at night.

Shortness of breath

Finding it hard to breathe, or getting easily breathless, is another common symptom of asthma. Those with asthma may find it gets worse during physical activity and can find it challenging to take a long, deep breath in or out.

Wheezing

Some people with asthma encounter a high-pitched whistling noise when they breathe. It is caused by the narrowing of the airways, making it more difficult for air to get out and producing a wheezing sound.

Mucus

Coughing up phlegm or mucus as a symptom could be an indication that your airways are inflamed due to uncontrolled or worsening asthma.

How is asthma diagnosed?

Whilst we can help provide treatment options for your asthma and help you regain control of your asthma, we cannot diagnose you ourselves. If you are experiencing asthma symptoms, it’s crucial to obtain a clinical diagnosis of asthma from a doctor or asthma specialist.

There are also resources online to help you better understand your symptoms, but if you have new symptoms you should consult your GP so that they may confirm an asthma diagnosis and offer treatment.

Your GP may ask you about your medical history, lifestyle, or family’s medical history to better understand your condition. Additionally, to confirm a diagnosis, they may run some tests, such as a peak flow or spirometry test, to measure your lung function or see if you have inflammation in your lungs.

If you receive a positive diagnosis, you may need to meet regularly with your GP or an asthma nurse to ensure your asthma is being adequately managed.

How to know if you have asthma

If you have any of the symptoms listed above, you may very well have asthma. Consult your GP for a formal diagnosis. They will be able to conduct some tests to figure out how best to manage the condition.

Ways to tell if you have asthma include:

  • A peak flow test - device that tests your lung function by measuring how fast you can breathe out.
  • A spirometry test - a machine that measures how fast you can breathe out and how much air you can retain in your lungs in a set time.
  • A FeNO test - a type of machine that measures the level of nitric oxide in your breath (an indicator of inflammation of the lungs).

Different types of asthma

Did you know there are several types of asthma, and many of them come with their own set of triggers? This sounds pretty daunting, but you’ll be relieved to know that most types of asthma require the same treatment and care.

That said, figuring out which type you have is essential in keeping it under control and avoiding flare-ups.

Childhood asthma

Children are those predominantly affected by asthma. Some children who are diagnosed with asthma find it drastically improves or even disappears as they grow up.

Exercise-induced asthma

If you are not diagnosed with asthma but experience asthma symptoms whilst exercising, you may have exercise-induced asthma. Predominantly affecting elite athletes or those doing physical activity in cold environments, this type of asthma causes breathlessness, coughing, or fatigue during or after exercise.

Exercised-induced asthma can be treated with different types of inhalers. Relievers are usually better used before you exercise as a 'pre-emptive' measure. They are administered before physical activity or other long-acting bronchodilator treatments.

Allergic asthma

Allergic asthma is - quite self-explanatorily - asthma triggered by allergens, such as pollens, pets, or dust mites. It can be managed with a reliever inhaler and by avoiding these triggers as much as possible.

Seasonal asthma

Some people only suffer from asthma flare-ups during certain seasons. For instance, it can occur in spring when there is lots of pollen in the air or winter when the temperature drops. For this reason, if you have seasonal asthma, you may only need to administer your asthma medication during said seasons.

Non-allergic asthma

This less common type of asthma does not have any definite causes. Unlike allergic asthma, there isn’t a trigger in the air causing symptoms. It can often develop later on in life and can be more severe than allergic asthma.

Occupational asthma

Occupational asthma is generally a type of allergen asthma. If you work in an environment with allergens in the air and only suffer from asthma symptoms during workdays, you may have occupational asthma.

Examples of workplaces that can trigger occupational asthma are construction sites, bakeries (flour in the air), or healthcare (dust on latex gloves).

Difficult asthma

Difficult asthma refers to asthma that is hard to manage or control. Other health issues can cause difficult asthma, such as allergies, or it can occur due to simply forgetting to administer the correct medicine.

Symptoms of difficult asthma include:

  • A persistent cough that does not go away.
  • Using your reliever inhaler three or more times a week.
  • Experiencing frequent asthma attacks.

Severe asthma

Formerly known as ‘brittle asthma’, this variation refers to asthma which suddenly and unexpectedly worsens. Severe asthma is not as easy to manage with standard asthma treatments and may require the individual to take a new kind of medication called biologics.

If you experience any of the following, you may have severe asthma:

  • You experience very frequent asthma attacks.
  • You experience ongoing symptoms despite administering the correct doses of your inhaler or medication.
  • You’re using your reliever inhaler more than three times a week.

Adult-onset asthma

Adult-onset asthma symptoms are the same as those of other variations of asthma. However, different variations of asthma generally begin during childhood.

Some possible causes of adult-onset asthma include exposure to smoke (either through smoking or secondhand), hormonal changes (only with female hormones), stress or even occupational asthma (see above).

Complications of asthma

Whilst it is a life-long condition, asthma can be easily managed and kept under control with medical treatments and professional support. Occasionally, however, uncontrolled asthma can create problems.

Common complications of asthma include:

  • Feeling fatigued all the time.
  • Stress, anxiety, or depression
  • Lung infections (such as pneumonia)
  • Disruptions from your daily life due to unplanned GP or hospital visits
  • Stunted growth in children
  • Asthma attacks
Symptoms of an asthma attack

Symptoms of an asthma attack

If you’re not sure exactly what an asthma attack feels like, here are some of the symptoms to look out for:

  • Your asthma is becoming more difficult to manage, leading to increased breathlessness, coughing, wheezing, or a tight feeling in your chest.
  • Your inhaler/treatment is not helping these symptoms.
  • You’re too breathless to speak properly, eat, or sleep.
  • You feel as though you cannot catch your breath.
  • Your peak flow scoring is lower than normal .
  • Children may complain of a tummy or chest ache.

It’s worth noting that these symptoms gradually build up over time, usually over several hours or days.

If you’re having an asthma attack, you should:

  • Stay upright (don’t lie down) and try taking slow, deep breaths.
  • Take one puff of your inhaler every 30-60 seconds, taking a maximum of 10 puffs.
  • If you do not have your inhaler to hand or feel your symptoms are not easing, call 999 for an ambulance.
  • Whilst waiting for the ambulance, repeat step 2 after 15 minutes.

Asthma attacks can be very scary, but it’s important to try and stay calm and follow the steps outlined above. 

Getting advice on asthma treatment

Whilst asthma can be successfully managed with an inhaler or medication, it’s not uncommon for people to take some time to find the best treatment methods for them.

If you’ve been diagnosed with asthma but want to explore other treatments or a better way to manage your prescriptions, speak to a clinician. Whether you want to switch inhalers or explore different medication routes, you’ll get the support and guidance you need to make the right choices about your treatment.

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This page was medically reviewed by Dr Daniel Atkinson, GP Clinical Lead on May 20, 2025. Next review due on May 20, 2028.

Last updated on May 20, 2025.

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When we present you with stats, data, opinion or a consensus, we’ll tell you where this came from. And we’ll only present data as clinically reliable if it’s come from a reputable source, such as a state or government-funded health body, a peer-reviewed medical journal, or a recognised analytics or data body. Read more in our editorial policy.

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