Shortness of breath

It's normal to get out of breath when you've overexerted yourself. But when breathlessness comes on suddenly and unexpectedly, it's usually a warning sign of a medical condition. Call your GP or GP out of hours service immediately if you have a sudden shortness of breath.

When to call a doctor

You should call your GP or GP out of hours service immediately if you have sudden shortness of breath. There may be a serious problem with your airways or heart. Call 999 for an ambulance you can’t get to speak to a GP, and your symptoms are getting worse.

Your GP will assess you over the phone. They may be able to reassure you. They may decide to arrange to see you or they may admit you to hospital by ambulance.

Shortness of breath can be as a result of conditions such as anxiety, which though are very unpleasant to experience, are not life threatening.

If you've struggled with your breathing for a while, don't ignore it. See your GP as it's likely you could have a long-term condition, such as asthma or chronic obstructive pulmonary disease (COPD). These conditions need to be managed properly.

If you are pregnant, later in pregnancy as your baby grows bigger, you may experience gradually increasing shortness of breath. You should mention this to your doctor. This is so they can check that you do not have an underlying problem such as anaemia.

Causes of sudden shortness of breath

Sudden and unexpected breathlessness is most likely to be caused by one of the following health conditions (see below).

A problem with your lungs or airways

Sudden breathlessness could be an asthma attack. This means your airways have narrowed.

You'll produce more phlegm (sticky mucus), which causes you to wheeze and cough. You'll feel breathless because it's difficult to move air in and out of your airways.

You should contact your GP, or GP out of hours service for advice.

Pneumonia (lung inflammation) may also cause shortness of breath and a cough. It's usually caused by an infection, so you'll need to take antibiotics.

If you have COPD, it's likely your breathlessness is a sign this condition has suddenly got worse.

Pulmonary embolism (a blood clot in the lungs) usually causes sudden shortness of breath with chest pain and coughing up blood. If you have symptoms of a pulmonary embolism, dial 999 immediately and ask for an ambulance.

Lung cancer can cause shortness of breath.  It can also cause a persistent cough, coughing up blood, an ache or pain when breathing or coughing, unexplained tiredness and weight loss.

If you have these symptoms you should arrange to see your GP as soon as possible. You should contact GP out of hours service if you think your condition is getting worse, and can’t wait until your GP is available.

A heart problem

It's possible to have a ’silent’ heart attack without experiencing all the obvious symptoms, such as chest pain and overwhelming anxiety.

In this case, shortness of breath may be the only warning sign you're having a heart attack. If you or your GP think this is the case, they'll give you aspirin and admit you to hospital straight away.

Heart failure can also cause breathing difficulties. This life-threatening condition means your heart is having trouble pumping enough blood around your body.

A combination of lifestyle changes and medicines or surgery will help the heart pump better and relieve your breathlessness.

Breathlessness could also relate to a problem with your heart rate or rhythm, such as:

Panic attack or anxiety

panic attack or anxiety can cause you to take rapid or deep breaths. This is known as hyperventilating.

Concentrating on slow breathing or breathing through a paper bag should help to bring your breathing back to normal.

More unusual causes

These include:

  • a severe allergic reaction (anaphylaxis)
  • partial collapse of your lung caused by a small tear in the lung surface, which allows air to become trapped in the space around your lungs (pneumothorax)
  • a rare and poorly understood lung condition that causes scarring of the lungs (idiopathic pulmonary fibrosis)
  • a collection of fluid next to the lung (pleural effusion)
  • a complication of diabetes where acids build up in your blood and urine (diabetic ketoacidosis)

Causes of long-term breathlessness

Reasons for long-term breathlessness include:

  • obesity or being unfit
  • poorly controlled asthma
  • chronic obstructive pulmonary disease (COPD) – permanent damage to the lungs usually caused by years of smoking
  • anaemia – a low level of oxygen in the blood caused by a lack of red blood cells or haemoglobin (the part of red blood cells that carries oxygen)
  • heart failure – when your heart is having trouble pumping enough blood around your body, usually because the heart muscle has become too weak or stiff to work properly
  • a problem with your heart rate or rhythm, such as atrial fibrillation (an irregular and fast heart rate) or supraventricular tachycardia (regular and fast heart rate)

More unusual causes of long-term breathlessness are:

  • a lung condition where the airways are abnormally widened and you have a persistent phlegmy cough (bronchiectasis
  • a recurrent blockage in a blood vessel in the lung (pulmonary embolism
  • partial collapse of your lung caused by lung cancer
  • a collection of fluid next to the lung (pleural effusion)
  • narrowing of the main heart valve, restricting blood flow to the rest of the body
  • frequent panic attacks, which can cause you to hyperventilate (take rapid or deep breaths) 

The information on this page has been adapted from original content from the NHS website.

For further information, read terms and conditions.

This page was reviewed October 2018

This page is due for review February 2021

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