Coughing Up Sputum (Phlegm)

What is sputum?

Your airways are lined with a thin layer of mucus that traps dust, germs and pollution. Tiny hairs (cilia) sweep it upward to the throat, where you normally swallow it without noticing, about a tablespoon or more a day. When the airways are inflamed or infected, they make more and thicker mucus. You then cough it up as sputum.

A cough that brings up sputum is called a productive or wet cough. For a detailed guide to phlegm colors, see productive cough.

What the amount and type of sputum suggest

Causes of coughing up sputum

Short-term (acute) causes

• Colds and post-viral cough: mucus from the nose and upper airways, settling within 1 to 3 weeks.
• Acute bronchitis: a chest cold. Sputum and cough for up to 3 weeks, usually viral, often without high fever.
• Pneumonia: infection of the lung tissue. Fever, breathlessness, fast breathing, chest pain on breathing in and feeling very unwell.
• Flu and COVID-19: start with a dry cough that can turn productive.
• Whooping cough: bouts of coughing that end in a "whoop" or vomiting, lasting weeks.

Long-term (chronic) causes

• COPD and chronic bronchitis: coughing up phlegm on most days for at least 3 months in 2 consecutive years, typically in current or past smokers. Worse in the morning.
• Bronchiectasis: permanently widened airways that collect mucus. Daily sputum, often in large amounts, and frequent chest infections.
• Asthma: usually a dry cough, but some people bring up thick white sputum, especially in flares.
• Smoking and vaping: "smoker's cough", most noticeable on waking.
• Cystic fibrosis: an inherited condition with very thick sputum from childhood.
• Tuberculosis: a cough lasting more than 3 weeks, sometimes with blood, plus fevers, night sweats and weight loss.
• Post-nasal drip and reflux: can cause throat mucus that feels like sputum, often with throat clearing.
• Lung cancer: a persistent cough, change in a long-standing cough, or blood in sputum, especially in smokers over 40.

Coughing up phlegm every morning

Sputum builds up overnight because you cough less while asleep. A small amount on waking that clears with a few coughs is common in smokers and people with allergies. Regular morning sputum for months suggests chronic bronchitis or bronchiectasis and deserves a check, including breathing tests.

When to worry about sputum

See a doctor if sputum lasts more than 3 weeks, keeps coming back, contains blood, or comes with breathlessness, chest pain, fever over 3 days, weight loss or night sweats. Act sooner if you have a lung or heart condition, a weak immune system, or are over 65.

How doctors investigate a productive cough

1. Questions: how long, how much sputum each day, color, smell, blood, smoking history, work exposures, travel and TB contact.
2. Examination: listening to the chest for crackles or wheeze, measuring oxygen levels.
3. Sputum culture: to identify bacteria and choose antibiotics, especially in bronchiectasis, COPD flares, cystic fibrosis or severe pneumonia.
4. Sputum tests for TB: usually two or three samples, tested by microscopy, a rapid molecular test and culture.
5. Chest X-ray: for pneumonia, TB or lung masses.
6. Spirometry: a breathing test for COPD and asthma.
7. CT scan of the chest: to diagnose bronchiectasis or investigate blood in sputum.

How to give a good sputum sample

• Collect it first thing in the morning, before eating or drinking.
• Rinse your mouth with water (not mouthwash) first.
• Take a few deep breaths, then cough deeply from the chest. Spit the sputum, not saliva, into the sterile pot.
• Close the lid tightly and return it to the clinic or lab within a few hours, or refrigerate it if told to.

Treatment and how to clear sputum

Treatment depends on the cause:

• Viral infections: fluids, rest, and acetaminophen (paracetamol) or ibuprofen for fever, following the label dose. Honey in warm water soothes a cough in adults and children over 1 year. Antibiotics do not help.
• Bacterial pneumonia, or infected flares of COPD or bronchiectasis: antibiotics prescribed by a clinician.
• COPD and asthma: inhalers, pulmonary rehabilitation, and stopping smoking.
• Bronchiectasis: daily airway clearance exercises taught by a respiratory physiotherapist, such as the active cycle of breathing technique or devices that vibrate the airways.

Tips that help bring up sputum

• Drink enough fluid so the mucus stays thin.
• Breathe in steam from a shower or a bowl of hot (not boiling) water. Do not use hot steam with young children.
• Try "huff coughing": take a medium breath and breathe out hard through an open mouth, as if fogging a mirror, then cough.
• Stay active. Walking helps move mucus.
• Stop smoking. Sputum often increases for a few weeks after quitting, then falls.

Over-the-counter expectorants such as guaifenesin have limited evidence but are safe for most adults when used as labeled. Cough suppressants are not useful for a wet cough, since clearing the sputum is the goal.

Frequently asked questions

What does coughing up sputum mean?

It means your airways are producing extra mucus, which you are clearing by coughing. Common causes are colds, bronchitis and pneumonia. Sputum that lasts months suggests a chronic lung condition such as COPD or bronchiectasis. Blood in it always needs medical review.

Is coughing up phlegm a good sign?

Clearing sputum is useful because it removes trapped germs and debris. During a chest cold it is a normal part of recovery. But continued sputum beyond 3 weeks, or large daily amounts, is not normal and should be checked.

What is the difference between sputum and phlegm?

They mean much the same thing. Sputum is the medical term for mucus coughed up from the lower airways and lungs. Phlegm is the everyday word and is sometimes used for any thick mucus, including from the nose or throat.

What color sputum is bad?

Red or pink sputum (blood), pink froth, rust-colored or very dark sputum, and sputum with a foul smell need prompt medical attention. Yellow or green sputum on its own is common during infections and does not automatically mean a bacterial infection.

What is a sputum culture test for?

A sputum culture grows any bacteria or fungi in your sputum to identify the cause of a chest infection and which antibiotics will work. It is used in pneumonia, bronchiectasis, COPD and cystic fibrosis flares, and special tests check for tuberculosis.