Coughing up blood (blood in phlegm)

Causes of coughing up blood

Common causes of coughing up blood include:

a long-lasting or severe cough
a lung or airway infection like a chest infection, pneumonia, tuberculosis or bronchitis
a problem with your airways that causes them to widen and produce more mucus (bronchiectasis)

Sometimes coughing up blood can be a sign of something more serious like a blood clot or lung cancer.

It's important to get it checked out as soon as possible.

Ask for an urgent GP appointment or get help from NHS 111 if:

you've coughed up a few small spots, flecks or streaks of blood, or noticed blood in your phlegm or handkerchief

you're coughing up more than just a few spots or streaks of blood
you're coughing up blood and finding it hard to breathe, have a very fast heartbeat or have pain in your chest or upper back

These symptoms could be a sign of a more serious problem like a blood clot in the lungs (pulmonary embolism).

Do not drive to A&E. Ask someone to drive you or call 999 and ask for an ambulance.

Bring any medicines you take with you.

Last Reviewed
15 April 2025