As autumn brings colds back into circulation, a cough is one of the most common symptoms people carry around for weeks. This article explains how long a cough normally lasts, what tends to be behind it, what can ease it, and the specific points at which the NHS says to get it checked.
How long should a cough normally last?
According to the NHS, a cough usually clears up on its own within three to four weeks. That is longer than many people expect. A cold can feel finished after a week, yet a dry or tickly cough often trails on well beyond the other symptoms as the airways settle down.
The NHS page on bronchitis gives a similar picture: bronchitis, an infection of the airways, usually gets better by itself in around three weeks. So a cough in its second or third week, in an otherwise well person, is common rather than alarming.
The figure that matters most is three weeks. The NHS describes a cough lasting longer than that as a persistent cough, and it is the point at which a routine GP appointment is recommended.
What usually causes a cough?
The NHS says most coughs are caused by a cold or flu. Other causes it lists include:
- smoking
- heartburn (acid reflux)
- allergies, such as hay fever
- infections such as bronchitis or COVID-19
- mucus dripping down the throat from the back of the nose
The same page notes that a cough is rarely a sign of something serious such as lung cancer. That is worth saying plainly, because a lingering cough can be worrying. At the same time, the reason a three-week limit exists is that a small number of causes need proper assessment, and they are easier to deal with when found early.
What helps at home?
The NHS advice for most coughs is straightforward and low-key. There is usually no need to see a GP, and the self-care suggestions are:
- Rest and drink plenty of fluids.
- If you have a high temperature or do not feel well enough for normal activities, stay at home and avoid contact with other people.
- Take paracetamol or ibuprofen for any pain, following the leaflet.
- Try a hot lemon and honey drink. The NHS suggests squeezing half a lemon into a mug of boiled water and adding one to two teaspoons of honey, drunk while warm.
The NHS is candid that evidence for hot lemon and honey, and for herbal medicines such as pelargonium, is limited. A warm drink may still soothe a sore throat, and it is unlikely to do harm for most adults. It is not suitable for babies under one year old, and the NHS advises against giving hot drinks to small children.
Some herbal treatments and medicines are not safe for everyone, for example during pregnancy, so a pharmacist or the leaflet is the place to check first.
If you are around other people, the habits covered in everyday habits that limit the spread of colds and flu apply here too: covering your mouth and nose when you cough and binning used tissues promptly.
Do cough medicines actually work?
A pharmacist can suggest cough syrups, cough medicines and cough sweets. The NHS says these will not stop a cough, although they may help you cough less. It also states that decongestants and medicines containing codeine will not stop a cough.
The research evidence is not strong. A Cochrane systematic review published in November 2014 looked at 29 placebo-controlled trials of over-the-counter medicines for acute cough, 19 in adults and 10 in children, covering 4,835 people in total. Its authors concluded there was no good evidence for or against the effectiveness of these medicines in acute cough.
Two further points from that review are worth knowing:
- Side effects were generally infrequent and mostly minor, such as stomach upset, headache and sleepiness.
- More side effects were reported with products containing antihistamines and with dextromethorphan, and the authors urged caution about giving antihistamines and centrally acting cough suppressants to children, because of their potential to cause serious harm.
The review is more than a decade old and its evidence base is limited, so it is best read as “uncertain” rather than “proven useless”. For children in particular, the NHS notes that some cough medicines should not be given to under-12s, so ask a pharmacist before buying anything.
A worked example: tracking the calendar
Because the three-week threshold is about time, a simple note of when the cough began can make a GP conversation easier. Illustrative arithmetic for a cough that starts on a Monday:
| Point | What it means |
|---|---|
| Day 1 | Cough starts alongside a cold |
| Day 7 (one week) | Cold symptoms fading; cough may continue |
| Day 21 (three weeks) | The point at which the NHS says to see a GP if the cough persists |
| Days 22 to 28 (up to four weeks) | Many ordinary coughs have finally settled by around this stage |
Three weeks is 3 × 7 = 21 days, so the date to watch is 21 days after the first day of the cough. If it began on 5 October, for example, day 21 falls on 26 October. A cough that is steadily improving is a different situation from one that is unchanged or worsening, and either is worth mentioning to the GP.
Why a lingering cough can be worth getting checked
A cough that goes on for weeks can reflect ongoing issues such as acid reflux, allergy or an airway infection that needs more than rest. It can also, rarely, be a sign of something more serious. The NHS lung cancer pages list a cough lasting longer than three weeks among the reasons to book a GP appointment, alongside other listed symptoms, and advise urgent contact if you cough up blood or see blood on a tissue.
That does not mean a long cough is likely to be cancer. As the NHS says on its cough page, it rarely is. The point is that a time limit takes the guesswork out: you do not have to decide whether your cough is “bad enough”, only whether it has passed three weeks.
Smoking is a common and changeable contributor. If you smoke and have a cough that will not shift, stopping smoking with NHS support is one of the more useful steps to discuss. Air quality can also play a part for some people; see London’s air quality and what the data shows.
What might happen at a GP appointment?
The NHS says a GP may listen to your chest with a stethoscope, take a sample of any mucus, or arrange an X-ray, an allergy test or a lung function test. Referral to a hospital specialist is described as rare.
Antibiotics are not normally prescribed for coughs. The NHS says they are given only where needed, for example for a bacterial infection or when someone is at risk of complications. Most coughs are caused by viruses, which antibiotics do not treat.
When to speak to a GP or NHS 111
Book a non-urgent GP appointment if:
- your cough has lasted more than three weeks
- you are losing weight for no reason
- you have a weakened immune system, for example from chemotherapy or diabetes
Ask for an urgent GP appointment or contact NHS 111 (by phone or online at 111.nhs.uk) if:
- the cough is very bad or getting worse quickly, such as a hacking cough or being unable to stop coughing
- you feel very unwell
- you have chest pain
- the side of your neck is swollen and painful
- you find it hard to breathe
- you cough up blood
The NHS bronchitis page adds that people over 65, people who are pregnant and people with long-term or weakened-immunity conditions should seek advice sooner. It also says to call 999 for emergencies such as severe breathing difficulty, pale, blue or grey lips or skin, sudden confusion, or being unable to wake a baby, and not to drive yourself to A&E.
Vaccination is part of reducing respiratory illness over winter too; see who is eligible for the autumn flu vaccine.
Giving a cough three weeks, and no longer
Most coughs are a leftover from a cold and settle within three to four weeks with rest, fluids and patience. Cough medicines have limited supporting evidence, so they are an optional comfort rather than a fix. The firm rule worth remembering is the three-week mark: past that, or sooner if any of the urgent signs above appear, it is time to speak to a professional rather than wait it out.
This is general information, not a substitute for advice from a doctor or other qualified health professional. If you are worried about a cough, speak to your GP or call NHS 111.
Sources: NHS; Cochrane
