If a person's skin or lips turn blue, it's usually a sign of low blood oxygen levels or poor circulation.
When blood becomes depleted of oxygen, it changes from bright red to darker in colour, and it is this that makes the skin and lips look blue.
The medical name for this bluish tinge is cyanosis. In darker-skinned people, cyanosis is easier to spot in the lips, gums and around the eyes.
What to do
Call 999 or go to your nearest hospital emergency department (A&E) if an adult is turning blue or has blue lips and is showing other warning symptoms, such as difficulty breathing, chest pain, or generally feeling unwell.
If just the fingers, hands, toes or feet are blue, see your GP – the cause is usually a blood circulation problem (see below).
Cyanosis that comes on gradually is usually the result of a long-term heart or lung problem – the person should see their GP as soon as possible.
Children and babies
Call 999 or go to your nearest hospital emergency department (A&E) if a child is turning blue. Trust your instincts and look for these other warning signs:
breathing difficulty – look out for fast breathing, or breathing with nostrils flared out, or chest muscles pulled in with every breath
sitting with shoulders hunched
making a grunting noise
floppy, tired or not moving around
You can read on to find the most common causes of cyanosis, but do not use this to diagnose yourself – always leave that to your doctor.
Cyanosis of 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 either:
a blockage in the blood supply to or from a limb, such as a blood clot
Raynaud's disease, a common condition that affects the blood supply to certain parts of the body, usually the fingers and toes
General cyanosis of the skin and lips
When all the skin and/or lips have a blueish tinge (see picture, top left), 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:
a blood clot in the arteries of the lungs (pulmonary embolism)
worsening of a long-term lung condition such as chronic obstructive pulmonary disease (COPD) or asthma
drowning or nearly drowning
being at a high altitude
A problem with the airways:
bronchiectasis, where the airways become abnormally widened, leading to a build-up of excess mucus, which makes the airways more vulnerable to infection
choking – what to do if a baby is choking
croup, a childhood condition (usually viral) affecting the airways, whichcauses a barking cough
epiglottitis, inflammation and swelling of the flap of tissue at the back of the throat, usually caused by infection
seizures that last a long time
A problem with the heart:
heart failure, where the heart fails to pump enough blood around the body
a heart defect that was present at birth (congenital heart disease) – cyanosis can happen if the defect allows oxygen-poor blood from the right side of the heart to enter the left side of the heart directly, instead of travelling to the lungs for more oxygen
cardiac arrest, where the heart stops beating
a drug overdose (of narcotics, benzodiazepines or sedatives)
exposure to cold air or water
a problem with the blood, such as abnormal haemoglobin (the blood cannot take up enough oxygen) or polycythaemia (a high concentration of red blood cells)
This 71-year-old's purple lips are the result of low blood oxygen levels caused by chronic obstructive pulmonary disease (COPD) and bronchiectasis