What is a cough?
A cough is a natural reflex that helps protect and clear the airways. When something irritates the throat or air passages — whether mucus, dust, smoke or an infection — the body responds by coughing to expel it. While coughing can be annoying, especially at night, it is usually a sign of the body doing its job, and most coughs are not a cause for concern.
Coughs are often described by how long they last. An acute cough lasts up to about three weeks and is usually caused by a minor infection like a cold. A cough lasting between three and eight weeks is sometimes called subacute, often lingering after an infection. A persistent or chronic cough lasts longer than about eight weeks and is more likely to have an underlying cause worth investigating.
Common causes
Coughs have many possible causes, ranging from very common and minor to ones that need medical attention. Common causes include:
- •Viral infections such as colds and flu
- •Chest infections
- •Postnasal drip (mucus running down the back of the throat)
- •Asthma
- •Acid reflux
- •Allergies, such as hay fever
- •Smoking
- •Some medications, which can cause a dry cough in certain people
Easing a cough at home
Most coughs from minor infections clear up on their own, and simple measures can ease the discomfort while you recover. Helpful steps include:
- •Resting and drinking plenty of fluids to stay hydrated
- •Warm drinks, or honey and lemon in warm water (not honey for babies under one)
- •Sucking on lozenges or hard sweets to soothe the throat
- •Avoiding smoke and other irritants
- •Keeping indoor air from becoming too dry
When a cough needs attention
While most coughs are harmless and pass on their own, certain features mean a cough should be checked by a doctor. A cough that lasts more than about three weeks without improving, or that keeps coming back, is worth assessing. So is a cough that is getting worse, or one accompanied by other symptoms such as breathlessness, chest pain, coughing up blood, unexplained weight loss, or a high fever that does not settle.
Some situations need more urgent attention. Sudden difficulty breathing, a cough with severe breathlessness, or choking should prompt emergency help. A cough in someone with a known heart or lung condition that changes or worsens also deserves prompt review. For most people, though, a cough is a temporary part of a minor illness — but knowing these warning signs means you can act when it matters.
Coughs in children
Coughs are very common in children, especially young ones who are building their immunity and catch frequent colds. Most childhood coughs are caused by minor viral infections and clear up on their own, though they can sometimes linger for a couple of weeks. As with adults, the main approach is comfort and fluids while the body recovers, rather than cough medicines, which are generally not recommended for young children.
Some features in a child's cough need prompt attention. A cough with difficulty breathing, fast or noisy breathing, or the skin sucking in around the ribs, should be checked urgently. A barking cough, a high-pitched sound when breathing in, or a child who seems very unwell, struggling to breathe, or unable to feed or talk, also needs urgent care. For babies, any breathing difficulty should be taken seriously.
For ordinary coughs, plenty of fluids, rest, and for children over one year, a warm drink with honey can soothe the throat (honey should never be given under one year). If a child's cough lasts more than about three weeks, keeps returning, or is accompanied by other worrying symptoms, it is worth seeing a doctor for assessment.
What the type of cough can suggest
The character of a cough can offer clues to its cause, though it is not a substitute for medical assessment when needed. A dry, tickly cough that produces no phlegm is common with viral infections, irritation, allergies, or as a lingering effect after a cold. It can also be caused by some medications or by acid reflux irritating the throat.
A chesty or productive cough that brings up phlegm is often associated with chest infections or the later stages of a cold, as the body clears mucus from the airways. The colour of phlegm is not always a reliable guide to whether an infection is bacterial and needs antibiotics, so it should not be relied on alone — discoloured phlegm does not automatically mean antibiotics are needed.
A cough that comes with wheezing or breathlessness may point to asthma or another airway condition, while a cough mainly at night or after lying down can suggest reflux or postnasal drip. These patterns can help a doctor work out the cause, which is why describing your cough clearly — when it happens, what it feels like, and any other symptoms — is helpful during an assessment.