Seeing blood when you cough is frightening. It might be a few pink streaks in your phlegm, a spot on a tissue, or a sudden metallic taste at the back of your throat. Whatever the amount, your first thought is probably "what is wrong with me?"
Coughing up blood has many possible causes. Some are minor, such as a throat irritated by a bad cough. Others are serious and need prompt treatment. Because you cannot tell the difference by looking, coughing up blood should always be checked by a doctor. This guide explains what the symptom means, what can cause it, how blood in mucus differs depending on its source, when to call 111, how doctors investigate it, and what treatment and prevention involve. It is general information, not a substitute for medical care. If you are coughing up blood right now, jump to the section on when to seek medical attention.
For general cough and cold reading, browse the Kiwiherb Wellness Hub.
Understanding coughing up blood
The medical term for coughing up blood is haemoptysis (spelt hemoptysis in the United States). It means coughing up blood or blood-stained mucus that comes from the lungs or airways, including the windpipe and the tubes that branch into the lungs.
Blood in your mouth or phlegm does not always come from the lungs. It can also come from the nose, sinuses, throat, gums or stomach, so doctors first work out where it is coming from. The amount matters too:
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Streaks or flecks of blood mixed in phlegm are the most common.
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Frank blood, where you cough up mainly blood, is more concerning.
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Massive haemoptysis is a large amount of blood, such as a cupful or more over a day, or any amount that makes it hard to breathe. This is a medical emergency.
Common symptoms associated with blood in phlegm
Blood in phlegm can look different depending on the cause and how long it has been in the airways. You may notice:
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Bright red, pink or frothy blood, which tends to come from the airways or lungs
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Dark red or brown specks or streaks, which may be older blood
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Blood mixed through thick mucus, which may look pink, rusty or brown
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A metallic or salty taste in the mouth, especially before or after coughing
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Other symptoms that help point to the cause, such as fever, shortness of breath, chest pain, wheezing, night sweats or unexplained weight loss
Many people also ask whether they can taste blood when they cough, even though they cannot see any. A metallic taste can come from small amounts of blood from irritated tissue in the nose, throat, gums or airways, particularly after a hard bout of coughing or with a sinus or chest infection. The taste alone does not tell you where the blood is from, so mention it to your doctor if it keeps happening.
Common causes of coughing up blood
If you are asking "why am I coughing up blood?", the causes fall into a few main groups. Doctors consider the amount of blood, how long it has been happening, your age, whether you smoke and your other symptoms.
Respiratory infections
Infections are among the most common causes of small amounts of blood in phlegm.
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Bronchitis. Inflamed airways from a viral or bacterial infection can cause a deep cough that irritates the lining and leaves streaks of blood in the phlegm, often after a long, hard cough with a cold or flu. From Sickness To Recovery explains why coughs can linger after an illness.
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Pneumonia. A lung infection can cause rust-coloured or blood-streaked phlegm, along with fever, chills, chest pain and breathlessness.
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Tuberculosis (TB). TB is less common in New Zealand than in many countries, but it does occur. It causes a cough lasting weeks, sometimes with blood, night sweats, fever and weight loss, and needs testing and specialist treatment.
Chronic conditions
Longer-term conditions can lead to repeated episodes of coughing up blood.
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Bronchiectasis. The airways become widened and scarred, so mucus pools and infections recur. It often causes a daily cough with large amounts of phlegm, and bleeding is a common complication.
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COPD and chronic bronchitis. Long-term lung damage, most often from smoking, can lead to infections and bleeding. Cystic fibrosis, an inherited condition with thick mucus and repeated lung infections, can also cause it.
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Lung cancer. Coughing up blood can be an early sign, particularly in smokers or former smokers, people over 40 and anyone with a long-standing cough, weight loss or hoarse voice. This is a reason not to put off getting checked.
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Heart problems. Heart failure can cause fluid to build up in the lungs, leading to pink, frothy phlegm and breathlessness.
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Pulmonary embolism. A blood clot in the lungs can cause coughing up blood along with sudden breathlessness, a rapid heartbeat and sharp chest pain. It is an emergency.
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Medicines. Blood thinners such as warfarin or newer anticoagulants can make bleeding more likely. Never stop a prescribed blood thinner without medical advice.
Trauma and injury
Injury can also cause bleeding in the airways.
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Chest injury. A blow to the chest, a fall or a car accident can bruise or tear lung tissue.
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Inhaled objects. In children especially, an inhaled object can injure the airways.
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Medical procedures. A bronchoscopy, biopsy or breathing tube can cause temporary bleeding.
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Forceful coughing or vomiting. This can tear tiny blood vessels in the throat or airways.
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Dry or irritated airways. Winter air, smoke and dry indoor heating can leave the nose and throat fragile, and a nosebleed can drain down the throat and be coughed up.
Blood in mucus: what it indicates
Not all blood you cough up is the same, and the source makes a big difference to what comes next.
Blood in sputum with cough (from the lungs or airways). Sputum is the phlegm brought up from the lungs and airways. Blood from here tends to be bright red or pink, often frothy because it is mixed with air, and is coughed up with a deep, chesty cough, sometimes with a burning or bubbling feeling in the chest.
Blood in mucus from the throat or nose. Blood from the upper airway or mouth is usually small streaks or spots in mucus cleared from the throat. It is often linked to a sore throat, sinus infection, nosebleed, dry air or hard throat clearing; it may come with a metallic taste and sometimes with visible bleeding from the gums, tonsils or inside the nose.
Vomiting blood (from the stomach). Blood from the stomach is usually dark red or brown, may look like coffee grounds, may contain food, and comes up with vomiting or nausea rather than coughing. Vomiting blood needs urgent medical help.
Because the difference can be hard to see, a doctor may ask you to describe the colour and amount, and may look at your nose, mouth and throat first. A photo of the tissue can help.
How mucus composition affects appearance
Blood does not look the same in every situation, because it mixes with mucus and saliva.
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Thick mucus can make a small amount of blood look pink, rusty or brown rather than bright red.
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Thin, watery fluid can make even a small amount of blood look bright and dramatic.
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Mucus from infection may be green or yellow with blood streaks. What's s...not? explains why mucus changes colour and texture.
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Old blood turns dark brown or black over time, so morning phlegm may have brown specks after bleeding the night before.
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Frothy, pink phlegm with breathlessness can mean fluid in the lungs, which needs urgent care.
How to decipher your cough? is a helpful general guide to different types of cough, but please do not rely on appearance to work out whether coughing up blood is serious. The only safe approach is to have it checked.
When to seek medical attention
Any time you cough up blood, you should see a doctor. How fast depends on how much blood there is and how you feel.
Signs that require immediate care
Call 111 or go to the nearest emergency department straight away if you:
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Cough up more than a few streaks or spots of blood
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Have trouble breathing, or feel breathless at rest
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Have chest pain, or pain in the upper back
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Have a very fast heartbeat, or feel dizzy, faint or confused
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Have blue or grey lips or skin
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Have coughed up blood after a chest injury, or are on blood-thinning medicine
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Are vomiting blood, or passing black, tarry stools
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Are coughing up frothy pink phlegm
Do not drive yourself. Ask someone to take you or call an ambulance, and take your medicines with you. While you wait, sit upright, stay as calm as you can, spit blood into a tissue or bowl rather than swallowing it, and do not eat or drink in case you need a procedure.
See a doctor promptly, the same day if you can, if:
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You have coughed up small flecks or streaks of blood, even once
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You have blood in your phlegm along with a fever, weight loss or night sweats
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You have a cough that has lasted more than three weeks
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You are a smoker or former smoker, or have a history of lung disease
If you are not sure how urgent it is, call Healthline on 0800 611 116 for free advice from a registered nurse at any time, or contact your GP or after-hours clinic.
Children. Coughing up blood in a child needs prompt medical advice. Small streaks may come from a nosebleed or irritated throat, but it can also be an infection or an inhaled object. Call 111 if a child is struggling to breathe, is blue around the lips, is unusually sleepy or limp, or has choked on something.
Expert evaluation and diagnostic tests
The first step is a conversation. Your doctor will ask how much blood you have coughed up, what it looked like, how long it has been going on, and about other symptoms, your smoking history, your medicines, recent illness and any injuries or procedures. They will examine your nose, mouth, throat, chest and heart, and check your oxygen levels.
Depending on what they find, they may arrange tests such as:
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Blood tests, including a blood count and clotting tests, to check for infection, anaemia or bleeding problems
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Chest X-ray and CT scan, which show causes such as pneumonia, a lung mass or fluid, with CT giving more detailed pictures
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Sputum tests, to look for bacteria or TB in the phlegm
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Bronchoscopy, where a thin, flexible camera is passed into the airways to find the source of bleeding
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Heart tests or a CT pulmonary angiogram, if a heart problem or blood clot in the lungs is suspected
Sometimes no cause is found, particularly with small amounts of blood. In that case, your doctor may suggest monitoring and follow-up scans.
Treatment options and outlook
Treatment depends entirely on the cause, which is why getting the right diagnosis matters so much. In general:
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Infections such as bacterial bronchitis or pneumonia are treated with antibiotics when needed. Viral infections usually settle on their own with rest and fluids.
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TB is treated with several antibiotics over many months, arranged through specialist services.
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Chronic lung conditions such as bronchiectasis and COPD are managed with airway clearance techniques, inhalers, prompt treatment of infections and regular follow-up.
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Blood clots in the lung are treated with blood-thinning medicines in hospital.
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Lung cancer is treated depending on its type and stage, and finding it early gives the best outcome.
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Heavy or repeated bleeding may need hospital treatment, such as medicines that help blood clot, a bronchoscopy to treat the bleeding site, a procedure to block the bleeding vessel, or in some cases surgery.
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Blood thinners. If you take them, your doctor will decide whether to adjust them.
Please do not treat coughing up blood at home with cough syrups, herbal remedies or home remedies. They will not treat the cause and may delay a diagnosis. Our Cough Syrup NZ Guide explains how cough syrups work generally, but with blood in your phlegm, see a doctor first.
The outlook varies widely. Many people who cough up small streaks of blood because of bronchitis or throat irritation recover fully, and the blood stops within days. For others, finding and treating a condition early leads to much better results, which is why it is always worth getting checked.
Lifestyle adjustments and preventive measures
You cannot prevent every cause, but healthy habits lower your risk of lung problems and help your airways heal.
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Stop smoking and avoid vaping. Smoking is the biggest risk factor for lung conditions that cause bleeding. In New Zealand, Quitline (0800 778 778) offers free support, and your GP or pharmacist can help with stop smoking medicines.
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Avoid smoke, dust and fumes, including second-hand smoke, wood burner smoke and workplace irritants.
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Treat chest infections early. See your doctor if a cold turns into a chest infection or a cough lingers for three weeks. How to beat the winter bugs, Beat the Bugs this Winter and Preparing for the colder months ahead offer practical tips for staying well.
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Stay up to date with vaccinations. Annual flu vaccines and other recommended vaccines reduce the risk of serious chest infections.
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Keep chronic conditions under control. Take your medicines as prescribed and attend check-ups.
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Keep your airways moist with plenty of fluids, and avoid hard, repeated throat clearing.
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Protect children. Keep small objects and nuts away from young children, and keep your home smoke-free and vape-free. Keeping Your Children Healthy During Cold and Flu Season has tips for families.
Frequently asked questions
Question: Is coughing up blood always serious?
Short answer: Not always, but it can be. Small streaks after a hard cough or with bronchitis are often minor, but the same symptom can be caused by serious conditions, so it should always be checked by a doctor.
Question: Why am I coughing up blood?
Short answer: Common causes include chest infections such as bronchitis and pneumonia, chronic lung conditions such as bronchiectasis and COPD, and irritation from a hard cough. Less often, it is caused by blood clots, heart problems, lung cancer or TB. Only a doctor can work out which applies to you.
Question: Is coughing up blood with mucus an emergency?
Short answer: Small flecks should be checked by a doctor promptly. It is an emergency if you cough up more than a few streaks, or have trouble breathing, chest pain, dizziness or a rapid heartbeat. Call 111.
Question: Why do I taste blood when I cough?
Short answer: A metallic taste can come from small amounts of blood from the nose, throat, gums or airways, often after hard coughing or with a sinus or chest infection. If it keeps happening, see your doctor.
Question: How can I tell blood in sputum with cough from blood in mucus from the throat?
Short answer: Blood from the lungs is often bright red or frothy and comes up with a deep cough. Blood from the throat or nose is usually small streaks linked to a sore throat, sinus problem or nosebleed. It is hard to tell without an examination, so get it checked.
Question: Can I treat coughing up blood at home?
Short answer: No. Home remedies and cough syrups do not treat the causes of bleeding. See a doctor, call Healthline on 0800 611 116 for advice, or call 111 in an emergency.