Overview
Can be from a cold, allergy, or something needing attention
What to notice
- How long the cough has lasted
- Whether it is dry or produces phlegm
- Whether it is worse at night, after meals or with exercise
- Whether there is fever, wheezing or shortness of breath
- Whether there is blood in the phlegm
Common cause groups
Short-term infections
Colds and other respiratory infections are common causes of a new cough and often improve as the infection settles.
Airway irritation
Smoke, dust, haze, allergies or other irritants can trigger coughing even without an infection.
Post-nasal drip or reflux
Mucus from the nose or irritation from acid reflux can sometimes cause a cough that keeps returning.
Lung or airway conditions
Asthma and other respiratory conditions may cause persistent cough, especially when accompanied by wheezing or breathlessness.
Associated signs
Fever
Shortness of breath
Wheezing
Sore throat
Runny or blocked nose
Phlegm
Chest discomfort
Blood in phlegm
How it may be assessed
A doctor will usually ask how long the cough has been present, whether it is dry or produces phlegm, and what other symptoms are present. Many short-lived coughs do not need extensive testing. If a cough persists or there are concerning symptoms, examination and selected blood tests or chest imaging may be considered.
Assessment and investigations
Blood Test
A full blood examination may be considered when infection, anaemia or another general health issue is part of the clinical picture.
Chest X-ray
A chest X-ray may be useful for some persistent coughs or when the doctor needs to look for changes in the lungs, but it is not required for every cough.
When to get checked
Consider seeing a doctor if a cough is persistent, keeps returning, is getting worse, interferes with sleep or daily activity, or comes with fever, wheezing, shortness of breath or unexplained weight loss.
Urgent warning signs
Seek prompt medical care for severe difficulty breathing, coughing up significant blood, severe chest pain, fainting, confusion, or rapidly worsening symptoms.
Frequently asked questions
How long does a cough usually last?
Many coughs caused by short-term infections improve gradually, but the duration can vary. A cough that persists, worsens or comes with other concerning symptoms should be assessed.
What is the difference between a dry cough and a cough with phlegm?
A dry cough produces little or no mucus, while a productive cough brings up phlegm. The type of cough can provide useful context but does not identify the cause by itself.
When should I see a doctor for a cough?
Consider medical assessment if the cough is persistent or worsening, or if it occurs with fever, wheezing, shortness of breath, chest pain, blood in the phlegm or other significant symptoms.