Cyanosis is where your skin or lips turn blue. It can be a sign of a serious problem.

You may notice a blue colour on your:

• lips
• tongue
• gums
• skin
• ears
• under your nails

If you have dark skin, cyanosis may be easier to see:

• on your lips, tongue and gums
• under your nails
• around your eyes

Your hands and feet are usually a normal temperature unless you also have poor blood circulation.

Cyanosis can mean there's not enough oxygen in your blood, or you have poor blood circulation. It can be caused by a serious problem with the:

• lungs, like asthma or pneumonia
• airways like choking or croup
• heart, like heart failure or congenital heart disease

Other causes of cyanosis include:

• Raynaud's, which affects your fingers and toes
• beta blockers, a medicine used to treat high blood pressure
• a blood clot that stops the blood supply to or from a limb
• being in cold air or water
• wearing clothing or jewellery that's too tight

Cyanosis is a symptom of many different conditions.

Treatment depends on the cause.