Why do people get asthma?

It’s difficult to say for sure why people get asthma. But thanks to research, we’re clear about some of the risk factors that make asthma more likely.

What causes asthma is different to what triggers asthma:

The causes are the underlying reasons why someone gets asthma in the first place.

Triggers are things like dust mites or pollen that can make asthma symptoms worse.

Here we look at what causes asthma, and where it’s possible for you to lower the risk. The good news is that some of these risk factors are things you can do something about.

Asthma and allergies tend to run in families

If there’s asthma, eczema, hay fever or other allergies in your family it makes asthma more likely.

If you have asthma yourself, your child is much more likely to have asthma too, particularly if both parents have asthma. There’s slightly more chance of asthma being passed on by the mother than the father.

Children with allergies can go on to develop asthma

If your child tends to get allergies they’re said to be ‘atopic’. Being prone to allergies is usually something that runs in families. And if your child has one allergy they’re more likely to get another one.

For example, children with eczema, and a family history of allergy, are more at risk of developing asthma than other children.

“GPs and researchers talk about the ‘atopic march’,” says Dr Andy Whittamore, Asthma UK’s in-house GP. “This is when allergies appear in children in a certain order, depending on their age.

“Sometimes allergies overlap, and sometimes your child will switch from one allergy to another. A small child with eczema may go on to have a food allergy, and then, as they get older, hay fever, and then asthma.”

Smoking increases the risk of your child developing asthma

Research has shown that smoking during pregnancy, and smoking around your baby or child, both significantly increase the risk of a child developing asthma or other breathing problems.

And smoking also has a part to play in adult onset asthma.

Being born early

A child is more at risk of asthma if they were born prematurely (before 37 weeks), especially if they needed a ventilator to help them breathe after the birth.

A low birth weight (when a baby is born small for their gestational age) can also be a risk factor for asthma.


Bronchiolitis is caused by a virus, and usually affects babies and young children under two years old. It leads to swelling in the lungs and airways. This makes it harder to breathe, and your child will cough and wheeze.

If your child has had bronchiolitis a lot, they could be more at risk of developing asthma as they get older.

Your baby will be more at risk of bronchiolitis if you smoke.

Exposure to triggers at work

Occupational asthma is a type of asthma caused by certain things found in the workplace, such as chemicals or dust from flour or wood.

If you haven’t had asthma before and then get it because of the work you do, and if your symptoms improve when you’re not at work, you probably have occupational asthma.

Occupational asthma is a common cause of adult onset asthma.

Female hormones

Hormones can play a part in triggering late onset asthma and some women first develop asthma during or after the menopause.

Pollution plays a part in causing asthma

Environmental pollution, including traffic fumes and chemicals from power plants, can make asthma symptoms worse and may play a part in causing asthma.

Studies suggest that children living near very busy roads are more likely to develop asthma.

Why are more people getting asthma and allergies?

Some researchers put the increase in asthma and other allergic conditions over the last few decades down to the fact that we live in much cleaner, more urban conditions. This means we have less contact with the ‘friendly bacteria’ that thrive in more rural, natural environments.

Along with fewer childhood infections, this has resulted in lowered immunity, and more chance of allergies, including asthma.

The 'hygiene hypothesis'

The idea that we’re missing out on exposure to useful microbes early in life began to be considered a while back with a theory known as the ‘hygiene hypothesis’. This was based on evidence that children growing up in large families, in unhygienic homes, had fewer allergies, including asthma.

More recent research suggests babies exposed to ‘friendly bacteria’ in the first few months of their lives are thought to have less risk of developing asthma and allergies.

This is why some studies show that children growing up on farms have fewer allergies, and other studies show that having a dog in the house when your baby is very small can protect them from allergies and asthma. The studies are based on exposure to friendly microbes in babies less than two or three months old.

But being around animals, or being in a natural environment, may not necessarily protect your child against asthma – other factors need to be taken into account, such as if there’s a family history of allergy and asthma.

“It’s important to remember this isn’t about us trying to be less clean and hygienic in the hope that it will cut the risk of developing asthma,” says Dr Andy Whittamore, Asthma UK’s in-house GP.

“The causes of asthma are much more complex. And it's worth remembering that good hygiene can help us avoid certain asthma triggers. Washing your hands well, for example, is an important part of preventing colds and flu which are a top trigger for asthma symptoms.”


How do you feel about your asthma?

Whatever you’re feeling about your asthma we’re here to give you support, advice, motivation and reassurance.

We all react differently to life’s experiences – and the same goes for having asthma. People tell us about a range of emotions about their asthma (or their child’s asthma), from relief at finally getting a diagnosis after having symptoms for a long time; to fear and anxiety about having another asthma attack.


“How you feel about your asthma often depends on where you are on your asthma ‘journey’”, says expert asthma nurse Kathy.

“You might not feel great about your asthma when you first find out you’ve got it, but OK with it later, once you’ve got used to it and you’ve learned how to manage it well.”

For the small percentage (about 5%) of people living with severe asthma the emotional challenges of dealing with symptoms every day can be greater.


Here we look at some of the emotions you might be experiencing around your asthma, and suggest some ways you might feel better.

Getting an asthma diagnosis came as a shock

Whether you have asthma yourself, or you’re a parent who’s just found out your child has asthma, you’ll probably be looking for answers and reassurance. And yes, it can come as a shock to be told you have a long-term condition.

You might be scared about how asthma will affect you, or worried about taking asthma medicines every day.

The good news is you’re in the right place to find answers to all your questions and concerns about asthma. And once you get the hang of looking after your asthma well, with the support of your GP or asthma nurse, you should feel more confident about things.

“Perhaps you’re not feeling positive now, but with time, support and advice you can get there,” says expert asthma nurse Kathy. “Sometimes a diagnosis can be a starting point for finding out as much as you can about asthma and getting on top of symptoms. And please don’t forget to call our Helpline.”

I’m scared – asthma attacks terrify me

An asthma attack can be a shock to the system, and a real knock to your confidence. Whether it’s yourself, or your child struggling to breathe, it’s a scary experience. And it can take some time to recover.

But there’s a lot you can do to cut your risk of an attack, as well as plenty of support and medicines to get you back on track if you do have an asthma attack.

Make sure you always carry your reliever inhaler with you so you’re confident you can deal quickly with any symptoms.

“Often people think an attack is going to come out of the blue – which makes it even more frightening,” says Kathy. “But most of the time there are signs and symptoms you can look out for, so that you can do something before they build up. Your written asthma action plan is a great way to do this.”


I’m worried asthma’s going to stop me getting on with my life

Sometimes it can feel like asthma’s stopping you doing what you want to do – particularly if you’re finding symptoms hard to control, or if triggers like exercise, alcohol or hay fever are a problem.

If you’re one of the 5% of people with asthma who have severe asthma, symptoms are a day to day frustration.

“If you’re feeling like asthma’s holding you back, find out how tried and tested tools and medicines are helping people live a life that’s symptom-free,” says expert asthma nurse Kathy.

“Even for people with asthma that’s difficult to control, there are lots of things you can do to get on with your life. That might mean making sure you’re getting good support, understanding what your triggers are, getting motivated to keep fit and healthy, or knowing what to ask when you go to your asthma review.”


I’m depressed - I don’t want to have a long-term condition to think about

Being told you have a long-term condition can be hard. And it’s quite common for people to feel depressed about it, particularly if they have severe asthma. It’s also understandable to feel fed up and resentful about having to take asthma medicine every day.

The good news is that if you follow three simple steps you can to keeping asthma in the background, and look forward to a life that’s pretty much symptom free:

Get into a good routine of taking your preventer inhaler every day as prescribed

Use a written asthma action plan to cut your risk of symptoms and an asthma attack

Go to your regular asthma reviews so you can check you’re on the right medicine and taking your inhalers in the right way, and keep your action plan up to date


I’m frustrated I won’t be able to keep fit because of my asthma

Some people find that having asthma holds them back from doing any kind of exercise. And it can trigger symptoms for some people.

But if you like keeping fit and want to stay active there’s plenty of evidence to say this will actually benefit your asthma.

So, however you decide to keep fit and well, whether it’s giving up smoking, walking to work, taking up a sport, or keeping yourself at a healthy weight, there’s no need to let asthma stop you. And in fact, it can be good for your asthma.

“With the right support and the right medicines, most people with asthma can do the things they enjoy, whether that’s gardening, hitting the high street with friends, or even raising money running marathons!” says Kathy.

Asthma doesn’t need to take over your life

You’ve come to the right place to learn all you can about your asthma. Find out about how the asthma medicines work away in the background to keep you symptom-free. And explore our living with asthma section to find out how you can get on with all the things you enjoy without asthma getting in the way.  

You can also read about other people’s experiences of asthma.

Whatever your questions or concerns about asthma, our asthma nurse specialists are just a call away on 0300 222 5800 (Monday-Friday, 9am-5pm). Or you can WhatsApp them on 07378 606 728.

Asthma Risk Checker

This is a simple check for people with asthma aged 12 years and over.  It only takes a few minutes and will show your risk of an asthma attack.  You will also get a personal asthma report packed with simple tips and advice to help you deal with your asthma.  Asthma hospitalises someone every 8 minutes.  Don't let it be you.  


Diagnosing asthma in adults

If you think you have asthma, make an appointment with your GP as soon as possible to get the treatment you need

Around 1 in 12 adults in the UK is being treated for asthma. People often think of asthma as something you get when you're a child. But it's not unusual to develop asthma as an adult. In fact asthma can develop at any age.

It's important to get a confirmed diagnosis. If you have asthma and it’s not diagnosed or looked after properly, it can make it even harder for your lungs to work well. And over time symptoms like breathlessness, coughing and tightness in the chest will be worse. Under-treated asthma may be life threatening.

The good news is there are lots of safe and effective medicines available. And if you take them as prescribed, asthma doesn't need to stop you doing anything you want to do.

What asthma symptoms should I look for?

What's triggering my asthma symptoms?

How is asthma diagnosed?

What's a 'trial of treatment'?

What happens after an asthma diagnosis?

Don't hesitate to ask for help

Read up on asthma

What asthma symptoms should I look for?

Common symptoms of asthma include:



tightness in the chest

feeling short of breath.

Not everyone with asthma will get all of the symptoms. Some people say they cough, but don't wheeze. Some people only have symptoms now and then. Others have symptoms a lot of the time, particularly the small percentage (about four per cent) of people with 'severe asthma'.

If you’ve noticed asthma-like symptoms, don’t ignore them. Make an appointment with your GP. Some GP practices have an asthma nurse, but the practice nurse might be able to help with asthma too.

The quicker you get diagnosed, the quicker you can get the right medicines to help deal with your symptoms.

What's triggering my asthma symptoms?

A trigger is anything that sets off your asthma symptoms, such as colds and flu, cigarette smoke, pollution, and cold air.

There are many different asthma triggers. You may just have one or two things that trigger your symptoms, or several. Sometimes it’s difficult to work out what your triggers are.

In adults, asthma symptoms are less likely to be triggered by allergies, such as house dust mites, pets and pollen, and more likely to be triggered by hormonal changes, or work.

Occupational asthma or work-related asthma can develop very quickly or take weeks, months or years to develop.

Avoiding your individual triggers, when it’s possible, can help reduce the risk of an asthma attack.

How is asthma diagnosed?

Asthma can be complex and take time to diagnose. This is because everyone’s asthma is different.

Getting a diagnosis for a child, for instance, is different from getting a diagnosis for an adult.

Also, the reasons for breathlessness can vary and in adults, especially older adults, it can be more difficult to tell the difference between asthma and other conditions that cause similar symptoms, such as heart disease or pneumonia.

The best way to confirm or rule out asthma is with asthma tests. But your GP will also want to know about your symptoms, when you get them, and if you've noticed what triggers them.

At your appointment the GP may:

ask about family history, workplace environment and lifestyle

do a breathing test (lung function test) which measures how your lungs are working

ask you to keep peak flow recordings or a symptom calendar

recommend other tests to help confirm a diagnosis – your GP or asthma nurse will decide which tests are suitable for you.

Unless you're unwell with symptoms, your GP may wait for test results before prescribing any treatments. This is to make sure you get the right medicines for you and that you're not taking medicines unnecessarily.

But if you are having symptoms, the GP may prescribe you asthma medicines before a diagnosis is confirmed to help you stay well. They will still need to arrange tests to confirm asthma at a later date.

What's a 'trial of treatment'?

The best way to confirm or rule out asthma is with asthma tests. But if you’re having symptoms your GP may decide to give you one or more asthma medicines to see if they help. This is known as a ‘trial of treatment’.

You may be asked to do breathing tests before and after the trial so it's clearer whether or not the asthma medicines made a difference.

If you respond well to the trial of treatment (if your symptoms start to get better), it's a good indication you could have asthma.

You may be asked to reduce or stop the medicines to see if your symptoms come back.

If the results show it's unlikely you have asthma, your GP may need to investigate other possible causes for your symptoms.

If at any point during the trial of treatment your symptoms get worse, contact your GP or asthma nurse immediately.


A guide to getting an asthma diagnosis for your child

Finding out if your child, baby or toddler has asthma can take time. From spotting symptoms, to having tests, to getting that final diagnosis, our expert guide explains each step and gives you easy tips to follow


Asthma attacks

Follow this emergency advice if you're having an asthma attack.

Important: for information on asthma attacks in children, visit our child asthma attack page.


You're having an asthma attack if you are experiencing any of these:

Your blue reliever isn't helping, or you need to use it more than every four hours

You're wheezing a lot, have a very tight chest, or you're coughing a lot

You're breathless and find it difficult to walk or talk

Your breathing is getting faster and it feels like you can't get your breath in properly

Asthma attacks can be fatal – three people die from asthma attacks in the UK every day. If you're having an asthma attack, it is vital that you act now.


What to do in an asthma attack:

Sit up straight

Don't lie down. Try to keep calm.

Take your blue inhaler

Take one puff of your reliever inhaler every 30-60 seconds, up to a maximum of 10 puffs.

Call 999 if you don't feel better

Do this if you feel worse at any point, or if you don't feel better after using 10 puffs of your reliever inhaler.

Take your blue inhaler again after 15 minutes

If you're waiting for the ambulance for longer than 15 minutes, take one puff every 30-60 seconds, up to a maximum of 10 puffs.

Important: This asthma attack information is NOT for people on a SMART or MART regime. If you are on a SMART or MART regime, speak to your GP or asthma nurse to get the right asthma attack advice for you.


The early warning signs of an asthma attack – and how to stop it coming on

Book an urgent appointment with your GP or asthma nurse if you are experiencing one or more of these signs:

Your symptoms are coming back (wheeze, tightness in your chest, feeling breathless, cough).

You’re waking up at night because of your asthma.

Your symptoms are getting in the way of your day-to-day routine (e.g. work, family life, exercising).

You need to use your reliever inhaler (usually blue) because of your asthma symptoms three times a week or more.

If you recognise any of these signs, they are telling you an asthma attack could be on its way. This is your chance to stop it coming on. Book an urgent appointment with your GP or asthma nurse or visit your local walk-in centre. They can help you to stop an asthma attack before it happens, or make it less serious so you don’t end up in hospital.


What to do after an asthma attack

There are three key steps you'll need to take as soon as possible after an asthma attack. These will help stop you from having another attack. It's tempting to think that after an asthma attack you can go back to living your life as normal. Asthma attacks are not normal, even for people with asthma. You shouldn't have to accept them as part of your everyday life.


After an asthma attack take these three simple steps to stay well:

  1. Book an urgent appointment with your GP or asthma nurse – even if you feel well

See them within two working days of your attack if you can. Tell them you need an urgent appointment because you've had an asthma attack.

If your asthma symptoms are getting worse at any point, ask for an urgent same day appointment.

  1. Keep taking your asthma medicines as prescribed

"Preventer medicines will take down the swelling in your airways. This will make your airways less sensitive to asthma triggers. It will also reduce your symptoms," says Asthma UK specialist nurse Kathy.

  1. Plan recovery time into your day

After an asthma attack it's important to try and rest as much as you need to. Ask friends and family to help with children, or get signed off work by your doctor.

Everyone's different so it's important to do what's right for you. Lots of people do feel physically and emotionally tired.

Make an urgent appointment with your GP or asthma nurse if any one of these happened to you:

You managed an emergency by using your blue inhaler

If you dealt with an asthma attack by using up to 10 puffs of your blue inhaler but didn't need to call an ambulance, you still need to see your GP the same day. Your GP or asthma nurse needs to check you're well and review your medicines.

You went to hospital, or called an ambulance

You still need to book a follow-up appointment with your GP or asthma nurse within two working days of leaving the hospital or being treated by paramedics. Your GP can check your notes and give you personal recovery advice.

If you had an asthma attack over two weeks ago but didn't see your GP at the time

It is still important to see your doctor or asthma nurse. Your asthma may still not be well controlled. You could be at risk of another asthma attack without realising.

You used any of your 'rescue pack' of steroid pills

If your asthma got bad enough that you had to take steroid pills your GP gave you, see your GP or asthma nurse within two working days. This counts as an asthma attack.


All information is from ASTHMA UK 2020




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