Blue or grey skin or lips (cyanosis)

Skin and lips turning blue, dusky or ashen grey is called cyanosis. It means one thing: the blood is short of oxygen. Lips, tongue or face that suddenly go blue are a reason to call an ambulance straight away, not to watch for half an hour. There is a harmless version too — bluish hands and feet in the cold — and below we set out carefully how to tell the two apart. But until the doubt is settled, act as though it is the dangerous one.

What it looks like, and where to look

There are two kinds of cyanosis and they mean quite different things. Blueness of the lips, tongue and the lining of the mouth means the whole body is short of oxygen, and that is dangerous. Blueness confined to the hands and feet, with lips and tongue a normal colour, usually means only that blood is moving slowly through the small vessels, most often because of cold.

You have to look in the right place, and the right place depends on skin colour. On pale skin the blue tinge shows on the face and lips. On brown and black skin the face will show you nothing: there, cyanosis looks like a greyish, ashen or earthy cast that is easy to miss. So look where the skin is thin and has almost no pigment:

• the lips, tongue and gums, which are the most reliable place of all;
• the inside of the lower eyelid, pulled down a little;
• the palms of the hands and the soles of the feet;
• the nail beds.

Look in daylight: yellow bulbs and screens distort colour beyond recognition. And keep two things in mind. First, cyanosis appears late — someone who is anaemic can be dangerously short of oxygen with no blue tinge at all, so normally coloured lips prove nothing if a person is struggling to breathe. Second, the pulse oximeter, the peg that clips on a finger, tends to read higher than the truth on dark skin, and a reading of 95 per cent in someone who is visibly deteriorating is no reason to relax.

When to call an ambulance immediately

Call an ambulance (in Spain, Italy, Portugal, Poland and Ukraine the single number is 112) if an adult or a child:

• has lips, tongue, face or skin that have suddenly turned blue or grey — on dark skin, check the lips, gums, tongue, palms, soles and the inside of the eyelids;
• also has difficulty breathing, noisy or wheezy breathing, or cannot finish a sentence;
• has chest pain, confusion, drowsiness, or loses consciousness;
• is a child who is limp and floppy, not responding as they usually do, whose head falls to the side or backwards, and who struggles to lift their eyes to your face;
• has turned blue after choking, inhaling or swallowing something, or after an insect sting, a dose of medicine or contact with an allergen.

While the ambulance is coming: sit the person upright or let them take whatever position makes breathing easiest, loosen the collar and the belt, open a window, do not leave them alone and give them nothing to eat or drink. If they have asthma and an inhaler, help them use it. If they are choking, give sharp blows between the shoulder blades and then thrusts under the ribs. If they are not responding and not breathing, start resuscitation: the emergency operator will talk you through it step by step until the crew arrives.

What is usually behind it

Cyanosis is not an illness, it is a sign. Behind it is something stopping oxygen from reaching the blood, or blood from reaching the tissues:

• the airway: choking and inhaling a foreign body, croup in a child with a barking cough and noisy breathing in, swelling of the throat in a severe allergic reaction, the suffocation of a severe asthma attack;
• the lungs: pneumonia, a severe flare-up of chronic obstructive pulmonary disease, a clot in the lung artery, a collapsed lung after injury;
• severe infection, where blood poisoning disturbs both breathing and circulation; in a child this can develop within hours;
• the heart: heart failure, serious rhythm disturbances, congenital heart disease in a baby;
• poisoning: an overdose of opioid painkillers or of sleeping tablets suppresses breathing. A separate story is substances that alter haemoglobin itself so that it stops carrying oxygen. Nitrites and nitrates do this, including those in well water given to infants, as do some medicines and industrial dyes. The skin then turns a slate-grey blue and an oxygen mask helps very little; only a doctor can recognise this, and the treatment for it is specific;
• hypothermia and near-drowning, and also the thin air of high altitude.

Children and babies

Children have less reserve and go downhill faster, so a blue child is always a reason to call an ambulance rather than wait until morning.

Newborns deserve particular attention. Congenital heart disease often declares itself in the first days or weeks: the baby goes blue while feeding or crying, tires quickly at the breast, breathes fast, sweats on the forehead while feeding and puts on weight poorly. A blue tongue or blue lips in a baby are never normal, at any age and however well the baby seems.

In older children the commonest causes are croup, a severe asthma attack and an inhaled foreign body. A child choking on a small part, a nut or a grape may make no sound at all: if they are not coughing and cannot draw breath, this is a matter of minutes.

Breath-holding spells deserve a mention of their own. Some toddlers, when frightened, hurt or angry, cry themselves out, hold their breath, go blue and become floppy for a few seconds. The spell ends by itself and the child comes round. It is terrifying to watch but not dangerous in itself — even so, the first time it happens the child must be seen by a doctor, because it can look very like a seizure and also like a heart rhythm problem.

When blueness is not dangerous: cold and acrocyanosis

There is a situation in which bluish hands and feet are normal, and it is worth knowing about so that you are not frightened for nothing. It is called acrocyanosis: in the cold the small vessels of the skin narrow, blood moves through them slowly and gives up more of its oxygen, so the fingers, hands, feet, tip of the nose and ears take on a bluish tinge. The hands are cold with it, but the lips, tongue and lining of the mouth stay pink, and that is the key sign that the oxygen is fine.

In newborns during the first days of life, bluish hands and feet with a pink face, a pink tongue and quiet breathing are perfectly ordinary. The baby is still learning to distribute blood flow, and it settles within a day or two. The same picture appears after a bath and in cool air during the first months.

The same category covers blueness from clothing that is too tight, from the tight elastic of a sock, a bracelet or a ring: it goes as soon as the pressure is removed. The check is simple — warm the hands or take off whatever is tight, and if the colour comes back within a few minutes and the lips have been pink throughout, there is nothing to worry about. If the blueness persists, spreads above the hands or reaches the lips, it is no longer acrocyanosis.

Raynaud's

This is a cause of blue fingers in its own right, and it looks characteristic. In the cold or with emotion the fingers, less often the toes, and sometimes the nose and ears, first turn sharply white as though drained of blood, then blue, and on warming up they redden, tingle and ache. An episode lasts from a few minutes to half an hour, and the border between the pale part and the normal part is sharp, as if drawn on.

Most of the time this is simply how someone's blood vessels behave: unpleasant, but harmless. Warm gloves and footwear help, as does stopping smoking, which narrows the vessels further, and avoiding work with vibrating tools; sometimes a doctor prescribes medicines that widen the vessels.

Sometimes, though, Raynaud's turns out to be a sign of a connective tissue disease. Arrange to see a doctor if the episodes began in adult life, affect only one hand, if sores or ulcers that are slow to heal have appeared on the fingertips, or if there is now joint pain and swelling, a rash, dry eyes and mouth, or unexplained tiredness.

What the doctor will do

In an emergency the first steps are to measure the oxygen saturation of the blood and to give oxygen; after that the cause is looked for — listening to the lungs, an ECG, a chest X-ray, blood tests, including a sample taken from an artery to find out exactly how much oxygen and carbon dioxide it holds. A child suspected of having a heart defect has an ultrasound scan of the heart.

There is no treatment "for blueness": the colour of the skin returns on its own as soon as the cause is dealt with. So what gets treated is the asthma attack, the pneumonia, the infection, the heart defect or the poisoning, each in its own way. Where the problem is a long-term condition with a permanent shortage of oxygen, the doctor arranges long-term oxygen therapy alongside treatment of the underlying disease.

Online consultation

An online consultation is no substitute for an ambulance: if the blueness has come on suddenly, ring the emergency number rather than opening a chat. But once the acute situation is over, or where episodes keep recurring, talking to a doctor online is genuinely useful. The doctor will go through exactly what you saw, where and in what light, whether the tongue was blue or only the fingers, and what went with it. They will help you tell harmless acrocyanosis from something that needs investigating, and explain how to use a pulse oximeter properly and why its readings on dark skin should be treated with caution. They will go through the discharge summary after a hospital stay, read the test results and scans, help you plan follow-up with a heart or lung specialist, and tell you which signs to watch for at home so that a deterioration is not missed.

This material is for information only and does not replace medical advice.