Chronic Cough: Causes, Assessment and Treatment

01Definition

What chronic cough means in adults

Mayo Clinic defines a chronic cough as one that lasts eight weeks or longer in adults, or four weeks in children. The Cambridge University Hospitals (CUH) leaflet uses the same eight-week threshold and adds that it is often a dry cough brought on by an irritating or tickling sensation in the throat.

An occasional cough is normal and useful: it clears irritants and mucus from the airways and helps prevent harmful material such as food, drink or smoke from entering the lungs. A cough that lasts for weeks, however, is usually due to a health problem, and Mayo Clinic notes that more than one cause is often involved at the same time. This guide is about adults; in children, the shorter time frame and different causes mean the assessment is different.

02Timing

Why eight weeks is not a waiting rule

The eight-week definition describes the condition; it is not a reason to wait before getting help. Mayo Clinic advises seeing a healthcare professional for a cough that lasts for weeks, especially if it:

• brings up sputum (phlegm) or blood
• disturbs your sleep
• affects school or work

Symptoms such as coughing up blood or becoming short of breath need attention well before the eight-week mark. A cough that lingers after a cold or flu is covered in our guide on post-viral cough.

03Symptoms

Symptoms and daily impact

Mayo Clinic lists symptoms that can accompany a chronic cough and give clues to its cause:

• a runny or stuffy nose, or a feeling of liquid running down the back of the throat (postnasal drip)
• frequent throat clearing, a sore throat or hoarseness
• wheezing and shortness of breath
• heartburn or a sour taste in the mouth
• rarely, coughing up blood

A persistent cough can be very tiring. Complications listed by Mayo Clinic include sleep disruption, headache, dizziness, vomiting, heavy sweating, leaking urine, broken ribs and fainting. The CUH leaflet adds that an oversensitive cough can lead to poor sleep, disordered breathing, anxiety, isolation and voice changes.

04Main causes

Common respiratory and upper airway causes

According to Mayo Clinic, the most common causes are tobacco use and asthma. Most chronic coughs are due to the following causes, alone or together:

• postnasal drip, when extra mucus from the nose or sinuses drips down the back of the throat, also called upper airway cough syndrome
• asthma, including cough-variant asthma, in which cough is the main symptom; it may come and go with the seasons, follow a respiratory infection or worsen with cold air, chemicals or fragrances
• infections, after which a cough can last long after other symptoms have gone; Mayo Clinic notes that whooping cough is a common but often unrecognized cause in adults, and less often fungal infections, tuberculosis or other mycobacterial lung infections are involved
• chronic obstructive pulmonary disease (COPD), including chronic bronchitis, which can cause a cough with colored sputum; most people with COPD are current or former smokers

Being a current or former smoker is one of the leading risk factors, and heavy exposure to secondhand smoke can also cause coughing and lung damage. For cough linked to mucus from the nose, see our guide on postnasal drip.

05Other contributors

Reflux, medicines and other contributors

Gastroesophageal reflux disease (GERD), in which stomach acid flows back into the esophagus, is another common cause. Mayo Clinic explains that the irritation can cause coughing, and the coughing can in turn make reflux worse. The CUH leaflet notes that reflux can reach the area around the vocal cords. Our guide on GERD cough covers this cause in detail; reflux is one possible cause, not the explanation for every chronic cough.

Some blood pressure medicines, the ACE inhibitors used for high blood pressure and heart failure, cause chronic cough in some people. CUH advises discussing any link between a new medicine and a cough with your doctor to see whether there is an alternative; do not stop a prescribed medicine on your own.

Less common causes listed by Mayo Clinic include aspiration of food or other material into the lungs, bronchiectasis, bronchiolitis, cystic fibrosis, idiopathic pulmonary fibrosis, lung cancer, nonasthmatic eosinophilic bronchitis and sarcoidosis.

06Assessment

Clinical assessment and selected tests

Because chronic cough often has more than one cause, the assessment looks for the common ones first and for clues to less common ones. It helps to tell the professional:

• how long the cough has lasted and how it started, for example after an infection
• whether it is dry or brings up phlegm, and its color, and whether you have coughed up blood
• smoking history and exposure to smoke, dust or chemicals
• accompanying symptoms: nasal symptoms, throat clearing, hoarseness, wheezing, breathlessness, heartburn
• triggers such as cold air, talking, exercise or fragrances
• all the medicines you take, including when each was started

Which tests are needed, if any, depends on these findings and is decided by the clinician. Mayo Clinic’s overview focuses on causes and does not suggest the same tests for everyone.

07Treatment

Treatment directed at the cause

Mayo Clinic notes that chronic cough usually goes away once the underlying cause is treated. The CUH leaflet gives examples of how treatment depends on the cause:

• postnasal drip: some over-the-counter or prescription nasal sprays or sinus rinses may help
• reflux: lifestyle and diet changes, posture and medicines to reduce reflux
• lung conditions that produce a lot of mucus: methods to help clear the phlegm, rather than trying to stop the cough
• medicines: reviewing with the doctor whether an alternative is possible

Stopping smoking and avoiding smoke exposure address the leading risk factor. Antibiotics, acid-reducing medicines, inhalers or other treatments are prescribed according to the cause, not started on your own. Our ENT practice in Bilbao offers scheduled assessment for adults when nose and throat causes such as postnasal drip, throat clearing or hoarseness are suspected; we do not provide a respiratory unit (consultations are in Spanish).

08Refractory cough

Oversensitive cough and supervised cough control

The CUH leaflet notes that chronic cough is often not resolved by medical treatment alone. Some people develop a hypersensitive cough, also called laryngeal hypersensitivity, in which the cough reflex is triggered by harmless stimuli. It is thought to involve abnormal functioning of the nerves in the throat and the parts of the brain that stop a cough. Common triggers include cold air, exercise, cleaning chemicals, reflux, talking or laughing, dehydration, some medicines, stress or anxiety, pollen and dust.

For this type of cough, a respiratory physiotherapist may teach cough control techniques, practiced regularly, to break the cycle in which a deep breath after coughing triggers more coughing. They combine swallowing, briefly holding the breath, slow smooth breathing through the nose, sips of water and specific breathing patterns, along with staying well hydrated and adapting to triggers, for example covering the nose and mouth with a scarf on cold days.

CUH is clear that these techniques should only be used after direct guidance from a physiotherapist, and should not be used when there is mucus on the lungs: during a cold or chest infection you should cough to clear it. If your cough brings up phlegm, see our guide on wet cough.

09Sources

Where the sources differ

Mayo Clinic states that chronic cough usually goes away once the underlying issue is treated, while the CUH leaflet says it is often not resolvable by medical management alone. The difference reflects their focus: Mayo Clinic describes causes and treatment of the underlying problem, while CUH addresses people referred to physiotherapy whose cough persists, often because the reflex has become oversensitive. A persistent cough after treatment does not mean nothing can be done, nor that no cause exists.

The sources also describe the typical cough differently: CUH describes chronic cough as often dry and tickly, while Mayo Clinic lists many causes that produce sputum, such as chronic bronchitis. That is why the distinction between a dry and a productive cough matters before any cough control technique is used.

Both pages are recent but not identical in date: the Mayo Clinic page is dated October 2024 and the CUH leaflet was approved in October 2025.

10Summary

In summary

A chronic cough lasts eight weeks or more in adults, but that is a definition, not a reason to wait: coughing up blood, shortness of breath, sputum, disturbed sleep or impact on daily life all justify seeing a professional sooner. The most common causes are smoking, asthma, postnasal drip, acid reflux, lingering cough after infections, COPD and ACE inhibitor medicines, and often more than one is involved.

Treatment targets the cause and is prescribed by a clinician. When the cough persists because the reflex has become oversensitive, physiotherapist-guided cough control can help, but not for a cough that brings up mucus. Keeping a record of each prescribed treatment, what it was meant to achieve, whether you took it as advised and when it is due for review helps make follow-up appointments more useful.