Cough in Adults: Causes, Red Flags and When to See a GP

A cough is one of the most common symptoms adults experience. It may be dry and tickly, chesty and phlegmy, irritating at night, worse after exercise, triggered by cold air, or left behind after a viral infection. Most coughs are not serious and settle on their own, but some need medical assessment, especially if they last longer than expected or come with warning symptoms.

A cough is not a disease by itself. It is a reflex that helps clear the airways of mucus, irritants, infection, smoke, dust, stomach acid or anything the body wants to remove. That is why coughs can come from many different causes: colds, flu, COVID-19, bronchitis, asthma, allergies, reflux, smoking, medicines, pneumonia, whooping cough, COPD, heart failure, blood clots, tuberculosis or, more rarely, lung cancer.

The key questions are: how long has the cough been going on, is it dry or productive, are you short of breath, are you coughing up blood, do you have chest pain, fever, weight loss or repeated infections, and are you at higher risk because of age, smoking, pregnancy or a long-term condition?

This guide explains the common causes of cough in adults, what different cough patterns may mean, when self-care is reasonable, when to see a GP, and when to call 999.

Important: this article is for general information only and should not replace medical advice. If you are very short of breath, have chest pain, cough up blood, feel seriously unwell or your symptoms are rapidly worsening, seek urgent medical help.

When a cough may be an emergency

Most coughs are caused by viral infections and improve without urgent care. However, a cough can sometimes be a sign of pneumonia, severe asthma or COPD flare-up, pulmonary embolism, heart failure, sepsis, a serious allergic reaction or another emergency.

Call 999 or go to A&E now if a cough comes with:

severe shortness of breath or struggling to breathe
blue lips, grey skin, severe drowsiness or confusion
chest pain, chest tightness or pain spreading to the arm, jaw, neck or back
coughing up a lot of blood, or blood with breathlessness or chest pain
fainting, collapse or feeling like you may pass out
severe wheezing that is not improving with usual treatment
symptoms of a severe allergic reaction, such as swelling of the lips, tongue or throat
being unable to speak in full sentences because of breathlessness
a severe asthma attack or COPD flare-up that is not responding to your rescue plan

If you are unsure whether breathlessness is serious, it is safer to seek urgent help. You may also find our guides to chest pain and when to worry, ECG results explained and heart palpitations useful if cough is linked with chest symptoms.

When to see a GP about a cough

Many coughs can be managed at home at first, especially if they follow a cold and you are otherwise well. The NHS says a cough will usually clear up on its own within 3 to 4 weeks, and NICE guidance notes that acute cough is usually self-limiting and often caused by a viral upper respiratory tract infection or acute bronchitis. For official information, see NHS cough guidance and NICE acute cough guidance.

Arrange a GP appointment or contact NHS 111 if:

your cough has lasted more than 3 weeks and is not improving
your cough is getting worse rather than better
you keep getting chest infections
you cough up blood, even a small amount
you have chest pain when breathing or coughing
you have persistent breathlessness or wheezing
you have a high temperature that is not settling
you feel very unwell, weak, confused or dehydrated
you have unexplained weight loss, night sweats or loss of appetite
you have a hoarse voice that persists
you smoke and have a new cough or a changed long-standing cough
you have asthma, COPD, heart disease, cancer, diabetes, kidney disease or a weakened immune system
you are pregnant and have a persistent or worsening cough

A cough that lasts more than three weeks does not mean cancer, but it should not be ignored. The NHS lists a cough that does not go away after 3 weeks, a long-standing cough that gets worse, coughing up blood, repeated chest infections, persistent breathlessness, chest pain when breathing or coughing, unexplained weight loss and persistent tiredness as possible lung cancer symptoms that should be assessed. See NHS lung cancer symptoms.

Dry cough vs chesty cough: does it matter?

People often describe coughs as dry or chesty. This can help, but it does not give a diagnosis on its own.

A dry cough is tickly and does not bring up much mucus. It may happen after a viral infection, with allergies, asthma, reflux, smoke exposure, some medicines, COVID-19 or irritation in the throat.

A chesty cough brings up mucus or phlegm. It can occur with colds, flu, bronchitis, pneumonia, COPD, bronchiectasis or smoking-related airway irritation. The colour of phlegm is not a perfect guide to whether antibiotics are needed. Yellow or green phlegm can happen with viral infections as well as bacterial infections.

What matters more is the whole picture: fever, breathlessness, chest pain, oxygen levels, how unwell you feel, risk factors, duration and whether symptoms are improving or worsening.

Common causes of cough in adults

1. Viral infections, colds, flu and COVID-19

Most short-term coughs are caused by viral infections. A cough may come with a runny nose, sore throat, sneezing, headache, body aches, mild fever, tiredness or a hoarse voice. The cough can continue after other symptoms have improved because the airways stay irritated.

Antibiotics do not work against viruses. Rest, fluids, time and symptom relief are usually enough for uncomplicated viral coughs. However, viral infections can sometimes trigger asthma, worsen COPD, lead to pneumonia, or cause prolonged symptoms in vulnerable people.

Seek medical advice if symptoms are worsening, you are very breathless, you have chest pain, you cough up blood, you feel very unwell, or your cough lasts beyond the expected recovery period.

2. Acute bronchitis

Acute bronchitis means inflammation of the larger airways, usually after a viral infection. It can cause a cough that lasts several weeks, often with mucus, chest soreness from coughing, wheeze or tiredness.

Although bronchitis can feel unpleasant, it is often viral and settles without antibiotics. NICE guidance aims to reduce unnecessary antibiotic use for acute cough because antibiotics usually make little difference for uncomplicated acute bronchitis and can cause side effects and antibiotic resistance.

Bronchitis is more concerning if you are older, frail, pregnant, immunosuppressed, have COPD, asthma, heart disease, or symptoms suggesting pneumonia or sepsis.

3. Post-viral cough

A post-viral cough can linger after a cold, flu or COVID-19. It may be dry, tickly and worse at night, when talking, laughing, going into cold air or exercising. The airways can remain sensitive even after the infection has cleared.

This type of cough often gradually improves over a few weeks. However, if it lasts more than 3 weeks without improvement, becomes worse, or comes with red flag symptoms, arrange medical advice.

4. Asthma

Asthma can cause cough, wheeze, chest tightness and breathlessness. Some adults mainly notice cough, especially at night, early morning, during exercise, in cold air, around pets, during pollen season, after viral infections, or around smoke, dust or strong smells.

A cough that keeps returning, wakes you at night, comes with wheezing, or improves with inhalers may suggest asthma. But asthma should be properly assessed rather than guessed. Tests may include peak flow monitoring, spirometry or FeNO testing depending on availability and symptoms.

For related tests, see AllHealth’s guide to spirometry results explained.

5. COPD and smoking-related cough

Chronic obstructive pulmonary disease, or COPD, is a long-term lung condition often linked with smoking, although not everyone with COPD has smoked. It can cause chronic cough, phlegm, breathlessness, wheeze and repeated chest infections.

A “smoker’s cough” should not be dismissed as normal. If you smoke or used to smoke and develop a new cough, a changed cough, coughing up blood, weight loss, breathlessness or repeated chest infections, seek medical advice.

Stopping smoking is one of the most effective ways to reduce cough, slow lung damage and lower cancer and cardiovascular risk. Even after many years of smoking, quitting still helps.

6. Pneumonia

Pneumonia is an infection of the lung tissue. It can be mild, but it can also be serious, especially in older adults, smokers, pregnant people, people with lung disease, heart disease, diabetes, kidney disease or a weakened immune system.

Symptoms may include:

cough, sometimes with phlegm
fever, chills or shivering
shortness of breath
chest pain that is worse when breathing or coughing
fast breathing or fast heart rate
feeling very weak or unwell
confusion, especially in older adults

Seek urgent medical advice if pneumonia is possible, especially if breathing is affected or you feel very unwell.

7. Allergies and hay fever

Allergies can cause cough through post-nasal drip, throat irritation, asthma symptoms or inflamed airways. Hay fever may cause sneezing, itchy eyes, runny nose, blocked nose, throat clearing and a dry cough, especially during pollen season.

Cough linked with allergies may be worse outdoors, around pets, dust, mould or certain seasons. It may improve with antihistamines, nasal sprays or avoiding triggers, but persistent cough should still be assessed if it lasts or comes with breathlessness, wheeze or red flags.

Related AllHealth guides: hay fever symptoms and treatment and sinusitis symptoms, causes and treatment.

8. Post-nasal drip and sinus problems

Post-nasal drip means mucus runs from the nose or sinuses down the back of the throat. This can trigger coughing, throat clearing, a sensation of mucus stuck in the throat, hoarseness or a cough that is worse when lying down.

It can be caused by colds, allergies, sinusitis, nasal polyps, irritants or changes in temperature. Treating the nasal or sinus problem often improves the cough.

If sinus symptoms are long-lasting, see AllHealth’s guide to chronic sinusitis.

9. Acid reflux and GORD

Acid reflux can cause cough even without obvious heartburn. Stomach acid or non-acid reflux can irritate the throat and airways, causing a dry cough, hoarseness, throat clearing, a sour taste, lump-in-throat sensation, symptoms after meals or cough worse when lying down.

Reflux-related cough may improve with avoiding late meals, reducing alcohol and caffeine, raising the head of the bed, weight management where relevant, and reflux treatment. However, persistent cough needs assessment because reflux is not the only cause.

Related AllHealth guide: heartburn, acid reflux and GORD.

10. Medicines, especially ACE inhibitors

Some medicines can cause cough. A common example is ACE inhibitor blood pressure medicine, such as ramipril, lisinopril, perindopril or enalapril. This can cause a dry, persistent cough that may start weeks or months after beginning treatment.

Do not stop prescribed blood pressure medicine without medical advice. If you think a medicine may be causing your cough, speak to a pharmacist, GP or prescriber. There may be alternatives.

Related AllHealth guides: high blood pressure and home blood pressure monitoring.

11. Whooping cough

Whooping cough, or pertussis, is a contagious bacterial infection. It can affect adults as well as children, and adult symptoms may not always include the classic “whoop”.

It often begins like a cold, then progresses to intense coughing bouts. The NHS describes early symptoms similar to a cold, followed after about a week by coughing bouts that may last a few minutes, be worse at night, bring up thick mucus, cause vomiting, and sometimes be followed by a whooping sound. See NHS whooping cough guidance.

Whooping cough matters because it can be serious for babies, pregnant people and vulnerable contacts. If you suspect whooping cough, seek medical advice and avoid close contact with babies and pregnant people until advised.

12. Lung cancer

Most coughs are not lung cancer. But lung cancer can cause cough, and early assessment matters. A persistent cough, a cough that changes, coughing up blood, repeated chest infections, persistent breathlessness, chest pain when breathing or coughing, unexplained weight loss, loss of appetite, tiredness or hoarseness should be checked.

This is especially important if you smoke, used to smoke, have occupational exposure to asbestos or silica, or have a long-standing lung condition. However, lung cancer can also occur in people who have never smoked.

If you have a cough lasting more than 3 weeks, or a changed long-standing cough, arrange a GP appointment.

13. Pulmonary embolism

A pulmonary embolism is a blood clot in the lungs. It can cause sudden breathlessness, chest pain that may be worse when breathing, coughing, coughing up blood, fast heart rate, dizziness or collapse. Sometimes there is also pain or swelling in one calf from a deep vein thrombosis.

This is an emergency. Call 999 if cough is associated with sudden breathlessness, chest pain, coughing blood, collapse or one-sided leg swelling and pain.

14. Heart failure

Heart failure can cause cough, especially when lying flat or at night, because fluid can build up in or around the lungs. It may also cause breathlessness, ankle swelling, fatigue, reduced exercise tolerance, waking at night gasping for air, weight gain from fluid, or needing extra pillows to sleep.

A cough caused by heart failure may be mistaken for a chest infection or asthma. Seek medical advice if cough is associated with breathlessness, swollen ankles, palpitations, chest discomfort or reduced ability to exercise.

Related AllHealth guides: cardiovascular risk, heart palpitations and swollen legs and ankles.

15. Tuberculosis

Tuberculosis, or TB, is less common in the UK than in many parts of the world, but it still occurs. TB can cause a persistent cough, coughing up blood, fever, night sweats, weight loss, tiredness and loss of appetite.

TB risk is higher in people who have had close contact with someone with TB, lived in or travelled from areas where TB is more common, are immunosuppressed, or live in crowded conditions. A persistent cough with night sweats or weight loss should be assessed.

16. Bronchiectasis

Bronchiectasis is a long-term condition where the airways become widened and more prone to mucus build-up and infections. It can cause a chronic productive cough, frequent chest infections, breathlessness, wheezing, tiredness and sometimes coughing up blood.

If you produce phlegm most days, keep getting chest infections, or cough up blood, you should see a GP.

What does the colour of phlegm mean?

Phlegm colour can provide clues, but it is not a reliable way to decide whether antibiotics are needed.

Clear or white phlegm can happen with viral infections, allergies, asthma, reflux or irritation. Yellow or green phlegm can occur when the immune system is fighting infection, but this does not automatically mean a bacterial infection. Rusty, pink or bloody phlegm needs medical advice, especially if it is more than a streak or happens repeatedly.

The NHS advises that coughing up blood should be checked as soon as possible because it can have common causes such as a severe cough or chest infection, but can sometimes be a sign of something more serious such as a blood clot or lung cancer. See NHS coughing up blood guidance.

How long should a cough last?

A cough after a cold or viral infection can last longer than people expect. Many acute coughs improve within 3 to 4 weeks. A cough lasting less than 3 weeks is usually called acute. A cough lasting 3 to 8 weeks may be called subacute. A cough lasting more than 8 weeks is usually considered chronic.

Duration matters, but it is not the only thing that matters. A cough lasting two days with severe breathlessness can be urgent. A cough lasting four weeks in someone otherwise well may still need a GP review, especially if it is not improving.

What can help a cough at home?

If your cough is mild, recent, and you are otherwise well, self-care may be enough at first.

rest if you feel unwell
drink enough fluids
avoid smoke, vaping, dust and strong smells
try honey in warm water or tea if suitable for you
use simple pain relief for fever or aches if safe for you
raise your head slightly at night if post-nasal drip or reflux is triggering cough
ask a pharmacist about cough medicines, especially if pregnant, breastfeeding, older, or taking other medicines

Honey should not be given to babies under 1 year, but this article is focused on adults. Some cough medicines may not be suitable with certain medical conditions or medicines, so ask a pharmacist if unsure.

If you have asthma or COPD, follow your personalised action plan. If your reliever inhaler is not helping, symptoms are worsening, or you are breathless at rest, seek urgent advice.

Do adults need antibiotics for a cough?

Usually not. Most short-term coughs are viral or caused by acute bronchitis, and antibiotics do not help viral infections. NICE advises that acute cough is usually self-limiting and gets better within 3 to 4 weeks without antibiotics. Antibiotics may be needed if there is suspected pneumonia, whooping cough in certain circumstances, a bacterial complication, or a high-risk patient where the clinician believes benefits outweigh risks.

Unnecessary antibiotics can cause side effects such as diarrhoea, thrush, allergic reactions and antibiotic resistance. If a GP does not prescribe antibiotics, it is not because the cough is being ignored; it may be because antibiotics are unlikely to help and could cause harm.

What tests might be needed for a persistent cough?

Tests depend on symptoms, duration, risk factors and examination findings. A clinician may ask about smoking, work exposures, asthma, reflux, allergies, medicines, infections, travel, TB exposure, weight loss and whether you are coughing up blood.

Possible tests include:

temperature, oxygen levels, pulse and breathing rate
chest examination
COVID-19, flu or other infection testing where relevant
chest X-ray if pneumonia, cancer, TB or other lung disease is suspected
spirometry or peak flow monitoring for asthma or COPD
FeNO testing in some asthma assessments
blood tests for infection, inflammation or anaemia
sputum sample if infection such as TB or bronchiectasis is suspected
CT scan or specialist referral if symptoms persist or imaging is abnormal

Cough at night: common causes

A cough that is worse at night can happen for several reasons. Post-nasal drip may worsen when lying down. Reflux may become more noticeable after late meals or when flat. Asthma often causes night-time cough. Heart failure may cause breathlessness and cough when lying flat. Dry air, dust mites, smoking exposure and some medicines can also contribute.

Night cough should be assessed if it persists, wakes you repeatedly, comes with wheeze, breathlessness, chest pain, swollen ankles, weight loss or coughing up blood.

Cough after eating

Cough after eating may suggest reflux, swallowing problems, aspiration, food allergy, asthma triggered by reflux, or irritation from spicy or acidic foods. If you cough or choke regularly when eating or drinking, or have difficulty swallowing, this should be assessed.

Difficulty swallowing, food sticking, unexplained weight loss, vomiting blood or black stools need prompt medical advice.

Cough after exercise

Cough after exercise can happen with asthma, exercise-induced bronchoconstriction, cold air, poor fitness, post-viral airway sensitivity, reflux, smoking-related lung disease or heart problems.

Exercise-related cough with wheeze or chest tightness may suggest asthma. Cough with chest pain, faintness, palpitations or unusual breathlessness should be assessed urgently.

Cough in smokers and ex-smokers

Smoking irritates the airways and increases the risk of chronic bronchitis, COPD, chest infections, heart disease and lung cancer. A long-standing morning cough may be common in smokers, but that does not mean it is harmless.

See a GP if you smoke or used to smoke and your cough is new, different, persistent, associated with blood, breathlessness, weight loss, chest pain, hoarseness or repeated infections.

Cough and pregnancy

Coughs in pregnancy are often caused by the same things as in other adults: viral infections, reflux, asthma, allergies or post-nasal drip. However, pregnancy changes which medicines are safe and can increase concern if there is fever, breathlessness, chest pain, dehydration or reduced oxygen levels.

If you are pregnant and have a persistent cough, high fever, shortness of breath, chest pain, coughing blood, worsening asthma or you feel very unwell, seek medical advice promptly. Ask a pharmacist, midwife or GP before using cough medicines.

Cough and older adults

Older adults may not develop classic symptoms with pneumonia or serious infection. Fever may be absent. Confusion, weakness, falls, reduced appetite, breathlessness or general deterioration may be the main signs.

A new cough in an older adult should be taken seriously if there is breathlessness, chest pain, confusion, reduced fluid intake, low oxygen levels, repeated infections, weight loss or a significant change from normal.

How to reduce the spread of infections when coughing

If you have a cough with a fever or feel unwell, try to reduce the risk of spreading infection. Stay home where possible, avoid close contact with vulnerable people, cover your mouth and nose when coughing, wash your hands regularly, dispose of tissues, improve ventilation and consider wearing a mask around others if you need to go out.

This is especially important around babies, older adults, pregnant people and people with weakened immune systems or long-term lung conditions.

The bottom line

Most adult coughs are caused by viral infections and improve within a few weeks. A cough can be dry, chesty, post-viral, allergy-related, reflux-related, asthma-related or caused by smoking, medicines or airway irritation.

However, a cough should be checked if it lasts more than 3 weeks, is getting worse, keeps returning, or comes with coughing up blood, chest pain, breathlessness, fever, weight loss, night sweats, hoarseness or repeated chest infections. Seek urgent help for severe breathlessness, chest pain, collapse, blue lips, confusion or coughing up significant blood.

If you are unsure, it is better to ask for advice than to ignore a persistent or changing cough.

FAQ: cough in adults

How long should a cough last in adults?

Many coughs caused by viral infections improve within 3 to 4 weeks. If a cough lasts more than 3 weeks and is not improving, or if it is worsening, arrange medical advice.

When should I see a GP for a cough?

See a GP if your cough lasts more than 3 weeks, is getting worse, keeps coming back, or comes with breathlessness, chest pain, coughing up blood, weight loss, night sweats, hoarseness or repeated chest infections.

When should I call 999 for a cough?

Call 999 if you have severe shortness of breath, chest pain, blue lips, confusion, collapse, coughing up a lot of blood, or you cannot speak in full sentences because of breathing difficulty.

Does green phlegm mean I need antibiotics?

Not always. Green or yellow phlegm can happen with viral infections as well as bacterial infections. Antibiotics depend on the whole clinical picture, not phlegm colour alone.

Can a cough be a symptom of lung cancer?

Yes, but most coughs are not lung cancer. Warning signs include a cough lasting more than 3 weeks, a long-standing cough that changes or gets worse, coughing up blood, repeated chest infections, chest pain, breathlessness, weight loss or persistent tiredness.

Why is my cough worse at night?

Night cough can be caused by post-nasal drip, asthma, reflux, dry air, dust, smoking exposure, some medicines or heart failure. It should be assessed if persistent or associated with breathlessness, wheeze, chest pain or swollen ankles.

Can acid reflux cause a cough?

Yes. Reflux can irritate the throat and airways, causing a dry cough, throat clearing, hoarseness or symptoms worse after meals or when lying down. Some people have reflux cough without obvious heartburn.

Can asthma cause cough without wheezing?

Yes. Some adults with asthma mainly have cough, especially at night, after exercise, in cold air or after viral infections. Testing such as spirometry or peak flow monitoring may help.

What is a post-viral cough?

A post-viral cough is a cough that lingers after a cold, flu or COVID-19 because the airways remain irritated. It often improves gradually, but should be checked if it lasts more than 3 weeks without improvement or comes with red flags.

Can blood pressure tablets cause a cough?

Yes. ACE inhibitors such as ramipril, lisinopril, perindopril and enalapril can cause a dry persistent cough. Do not stop them suddenly; ask a pharmacist or GP for advice.

Is coughing up blood always serious?

Coughing up blood can happen after a severe cough or chest infection, but it can also signal serious problems such as a blood clot or lung cancer. It should be checked as soon as possible. Call 999 if there is a lot of blood or breathlessness or chest pain.

Can allergies cause a cough?

Yes. Allergies and hay fever can cause cough through post-nasal drip, throat irritation or asthma symptoms. It may come with sneezing, itchy eyes, runny nose or blocked nose.

Can whooping cough affect adults?

Yes. Adults can get whooping cough. It may cause intense coughing bouts, often worse at night, sometimes with vomiting or thick mucus. It can be dangerous for babies and vulnerable contacts.

What tests are done for a persistent cough?

Tests may include chest examination, oxygen levels, chest X-ray, spirometry, blood tests, sputum tests, infection testing or referral for further imaging depending on symptoms and risk factors.

Do cough medicines work?

Some people find cough medicines soothing, but benefits are often modest. Honey, fluids and avoiding irritants may help. Ask a pharmacist if you take other medicines, are pregnant, breastfeeding or have long-term conditions.

Can smoking cause a cough?

Yes. Smoking irritates the airways and can cause chronic cough, phlegm, COPD and repeated infections. A smoker’s cough should still be checked if it is new, changing, persistent or associated with blood, breathlessness, chest pain or weight loss.

Can heart problems cause a cough?

Yes. Heart failure can cause cough, especially when lying flat or at night, often with breathlessness, swollen ankles, fatigue or reduced exercise tolerance. Seek medical advice if these symptoms occur.

Should I stay home if I have a cough?

If you have a cough with a high temperature or feel unwell, try to stay home and avoid close contact with others, especially vulnerable people. Good hand hygiene, tissues and ventilation can reduce spread.

Can anxiety cause a cough?

Anxiety can contribute to throat clearing, tight throat sensations or breathing pattern changes, but a persistent cough should not automatically be blamed on anxiety. Other causes should be considered, especially if there are red flags.

What should I tell the GP about my cough?

Tell them how long it has lasted, whether it is dry or productive, phlegm colour, smoking history, fever, breathlessness, chest pain, blood, weight loss, night sweats, medicines, asthma/COPD history, reflux symptoms, allergies and any recent travel or infections.