What counts as a chronic cough

A cough that lasts more than eight weeks can wear a person down, affecting sleep, work and relationships. Chronic cough is defined as a cough that lasts beyond eight weeks, but the definition applies only to a simple cough without other significant symptoms. If a cough comes with small amounts of blood, significant weight loss or breathlessness, there is clearly no need to wait eight weeks before seeking medical attention.

One of the most common causes of a simple cough is an upper respiratory tract infection, commonly known as a cold, and a cough can last up to six weeks after a cold, so in most of these cases it is not necessary to investigate. A cough lasting between six and eight weeks is termed a subacute cough, and may need investigation such as a chest X-ray.

Why the chest X-ray is normal

Many patients have already had several chest X-rays that were normal. This is because chronic cough often arises outside the lungs, from acid reflux, nasal and sinus problems, or from medications such as some blood pressure tablets. In others, asthma is the cause, or the cough reflex itself has become over sensitive.

The main causes

Acid reflux. A significant proportion of patients with chronic cough actually have gastro-oesophageal reflux, often with mild or no reflux symptoms apart from the cough itself. The cough is often worse lying flat, when reflux tends to worsen. Confirming reflux as the cause needs 24-hour oesophageal pH monitoring, which many patients find intrusive, so in many cases it is reasonable to try a course of acid-suppressing medicine (a proton pump inhibitor) instead. Patients should not do this on their own: a trial of treatment is only considered once there are no alarm symptoms in the clinical picture.

Post-nasal drip. Allergic rhinitis usually presents with a persistently blocked nose, nasal discharge and frequent sneezing, but a significant number of patients with it also have a chronic cough. Excess mucus dripping down the back of the nose irritates the throat and triggers the cough reflex, so the cough is often preceded by throat irritation. In most cases the symptoms settle with treatment of the rhinitis, such as steroid nasal sprays and/or regular antihistamines.

Cough-variant asthma. Most patients with asthma have cough, breathlessness, chest tightness and wheezing, but some have cough as the only symptom. A careful history and examination with lung function tests (spirometry and FeNO) can usually confirm cough-variant asthma reliably. Treatment is the same as for asthma.

Blood pressure medication. ACE inhibitors are an important part of the treatment of high blood pressure and also protect the kidneys from its effects. Unfortunately up to 35% of patients on them develop a cough, which can start almost immediately or up to six months after starting the medicine. In most patients the cough resolves within one to three weeks of stopping it.

Cough hypersensitivity syndrome. In a small number of patients the cough reflex itself has become over-reactive. These patients are often distressed, because treatment for the other causes of chronic cough has failed, so identifying them carefully is important. Treatment may include nerve-calming medicines and certain antidepressants used at low dose for their effect on the cough reflex, and non-drug approaches such as speech and language therapy, hydration and airway-soothing techniques remain important.

How we investigate

A careful history and a focused clinical examination are the first step. Most patients then need simple investigations such as spirometry and a chest X-ray. A trial of treatment may be started once the important causes of cough have been reliably excluded. A careful and step by step assessment usually finds the answer.

How chronic cough is treated

Treatment may include speech therapy techniques and medicines that calm the cough reflex, and newer treatments are on the horizon.

Speech and language therapy. This involves learning to recognise the early signs of a cough, such as throat irritation, and using specific breathing techniques, including diaphragmatic breathing, to control or suppress it. Laryngeal and airway training usually needs the help of an experienced speech and language therapist to achieve good results.

Cough-calming medicines. A non-opioid cough suppressant is probably the most commonly used, and is found in many pharmacy cough medicines; although often sold as non-drowsy, it can still cause some sleepiness. An opioid cough suppressant, available on prescription, is effective but can cause dependence if used excessively for long periods, so it is usually reserved for when the first-line suppressant fails. Sedating antihistamines help a cough aggravated by allergic inflammation; they may cause sleepiness but not dependence. Demulcents such as honey, pectin, glycerin and a variety of herbal options soothe the throat, help a large number of patients, and are readily available over the counter.

You do not have to put up with it

Persistent cough is treatable, and you do not have to put up with it.

Lung and Respiratory Conditions: A Patient Guide · Coughing Up Blood (Haemoptysis): Do Not Ignore · The Aeden Physicians

Frequently Asked Questions

What counts as a chronic cough?

Any cough that persists beyond eight weeks is considered a chronic cough. If a cough comes with blood, significant weight loss or breathlessness, do not wait eight weeks before seeing a doctor.

Why is my chest X-ray normal but I still cough?

A large percentage of acute and chronic coughs are caused by problems outside the lungs, such as an upper respiratory tract infection or acid reflux, so the chest X-ray is often normal.

Can a chronic cough be treated?

Yes. Most cases of cough can be treated or controlled in the long term with the appropriate treatment.