What is asthma?

In asthma, the airways are more sensitive than usual. When they react to a trigger, the lining becomes inflamed and swollen, the muscles around the airways tighten and extra mucus can build up. This narrows the airways and can cause:

  • wheeze
  • a cough, often worse at night or early in the morning
  • chest tightness
  • breathlessness

Symptoms often come and go, and they can vary from day to day. Asthma can start at any age, including in adults who have never had breathing problems before.

How asthma is diagnosed

There is no single test for asthma. A GP will usually start with your symptoms, when they happen and what seems to trigger them, alongside your personal and family history of asthma, eczema or hay fever.

Current UK guidance recommends objective tests to support a diagnosis where possible. These may include a blood test for eosinophils, a FeNO breath test, spirometry before and after a reliever, or peak flow readings over a couple of weeks. Some of these tests need to be arranged face to face, through your NHS practice or a specialist service.

Knowing your triggers can help you reduce flare-ups. Common triggers include:

Colds and chest infections

Viral infections are one of the most common causes of asthma flare-ups, particularly in autumn and winter.

Allergens

Pollen, house dust mites, pet dander and mould can all trigger symptoms in people with allergic asthma.

Smoke and air pollution

Cigarette smoke, second-hand smoke, vapes and polluted air can irritate the airways and make asthma harder to control.

Cold air and weather changes

Cold, damp air, sudden temperature changes and thunderstorms can bring on symptoms.

Exercise

Exercise is good for asthma, but it can trigger symptoms in some people. Good overall control usually helps, and your plan may include advice for before exercise.

Some medicines

Anti-inflammatory painkillers such as ibuprofen or aspirin, and beta blockers, can worsen asthma in some people. Always mention your asthma when starting a new medicine.


When to seek urgent medical help

Call 999 or go to A&E immediately if:

  • your reliever inhaler is not helping
  • you are too breathless to speak, eat or sleep
  • your breathing is getting faster and you feel you cannot catch your breath
  • your lips, tongue or fingertips look blue or grey
  • you feel drowsy, confused or exhausted

These can be signs of a severe asthma attack, which needs urgent treatment. While you wait for help, follow the emergency steps in your personal asthma action plan.

Frequently asked questions

Can asthma start in adulthood?

Yes. Asthma can develop at any age, including in adults who have never had breathing problems before. Adult-onset asthma is sometimes linked to work, allergies or infections, so it is worth discussing new symptoms with a GP.

Is a blue inhaler on its own enough to treat asthma?

For most adults, no. Current UK guidance recommends treatment that includes an inhaled corticosteroid, because a reliever on its own does not treat the inflammation behind asthma. If you only use a blue inhaler, a review is worthwhile.

What is a personal asthma action plan?

It is a written plan, agreed with your clinician, that sets out your usual treatment, how to recognise when your asthma is getting worse and what to do in an emergency. Everyone with asthma should have one.

How often should I have an asthma review?

At least once a year, and sooner if you have had a flare-up, needed steroid tablets or changed treatment.

Can an online GP help with asthma?

An online GP can review your symptoms, check how your treatment is working, talk through inhaler technique and issue a private prescription where clinically appropriate. A severe asthma attack needs urgent in-person care, and some tests need to be arranged face to face.

Further Reading and Hub Links

Visit our Lung Health hub or browse more health topics in the AccessGP Knowledge Base. Our guide to inhaler types and technique may also help. For more on asthma, see the NHS guide to asthma.

If you would like a GP to review your asthma, talk through your inhalers or check whether your treatment is working as well as it could, you can book an online appointment at a time that suits you. Our GMC-registered GPs offer same-day or next-day video and telephone consultations.

Our GMC-registered GPs offer same-day or next-day video and telephone consultations, providing convenient access to medical advice when you need it.

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Locations We Serve:
Available to patients in Sevenoaks, Warwick, Peterborough, Hornchurch, Newcastle upon Tyne, Birmingham and throughout England.

Reviewed by Dr Zamiel Hussain, GP · GMC number 7486123 (check the GMC register) · About Dr Hussain
Updated: 7 November 2026