If a person's skin or lips turn blue, it's usually caused by low blood oxygen levels or poor circulation. It can be a sign of a serious problem, so it's important to seek medical advice.
When blood becomes depleted of oxygen, it changes from bright red to darker in colour, and it's this that makes the skin and lips look blue.
In darker-skinned people, the blue tinge may be easier to spot in the lips, gums and around the eyes.
The medical name for this blue tinge is cyanosis.
What to do
Call 999 or go to your nearest hospital emergency department (A&E) immediately if you notice an adult or child suddenly turning blue, particularly if they have other symptoms, such as difficulty breathing or chest pain. This could be a sign of a life-threatening problem.
See your GP or call NHS 111 if you have cyanosis that comes on very gradually, or affects just the fingers, hands, toes or feet. This is usually the result of a less serious problem with blood circulation, but it should still be checked by a doctor.
Common causes of cyanosis
Some of the main causes of cyanosis are described below, but you shouldn't use this to diagnose yourself - always leave that to a doctor.
Cyanosis that just affects the hands, feet or limbs
If just the fingers, toes or limbs have turned blue and feel cold, it's known as peripheral cyanosis.
The cause is usually poor circulation resulting from:
- Raynaud's phenomenon - where the blood supply to certain parts of the body, usually the fingers and toes, becomes temporarily reduced when exposed to cold temperatures
- peripheral arterial disease (PAD) - where a build-up of fatty deposits in the arteries restricts blood supply to the legs
- beta-blockers - medication commonly used to treat high blood pressure
- a blood clot blocking the blood supply to or from a limb
Cyanosis that affects the skin generally and/or lips
When all the skin and/or lips have a blue tinge, it's known as central cyanosis, and is usually a sign of low levels of oxygen in the blood. Common causes for central cyanosis are listed below.
A problem with the lungs:
- worsening of a long-term lung condition, such as asthma or chronic obstructive pulmonary disease (COPD)
- lung infections, such as pneumonia, bronchiolitis or whooping cough
- bronchiectasis - where the airways in the lungs become abnormally widened
- a pulmonary embolism - a blood clot in the arteries of the lungs
- neonatal respiratory distress syndrome (NRDS) or acute respiratory distress syndrome (ARDS) - where the lungs can't provide enough oxygen for the rest of the body
- drowning or nearly drowning
A problem with the airways:
- choking - read what to do if someone is choking
- croup - a childhood condition, usually caused by a virus, that affects the airways and causes a barking cough
- epiglottitis - inflammation and swelling of the flap of tissue at the back of the throat, usually caused by infection
- anaphylaxis - a severe allergic reaction that can restrict the airways
A problem with the heart:
- heart failure - where the heart fails to pump enough blood around the body
- congenital heart disease - a heart defect present at birth that can affect how blood travels around the heart and body
- cardiac arrest - where the heart stops beating
- exposure to cold air or water
- being at high altitude
- fits (seizures) that last a long time
- a problem with the blood, such as abnormal haemoglobin (the blood can't take up enough oxygen) or a high concentration of red blood cells (polycythaemia)