A cough, also known as tussis, is a voluntary or involuntary act that clears the throat and breathing passage of foreign particles, microbes, irritants, fluids, and mucus; it is a rapid expulsion of air from the lungs.
Coughing can be done deliberately or as part of a reflex. Although coughing can be a sign of a serious illness, more often, it will clear up on its own without the need for medical attention.
In this article, we will cover the possible causes, diagnosis, and treatments for coughs.
Fast facts on coughs
Here are some key points about coughs. More detail and supporting information is in the main article.
- Some germs use coughing to spread to new hosts.
- There is a wide array of potential causes of coughs.
- Some types of cough only occur at night.
- If the cough is difficult to diagnose, a chest X-ray may be necessary.
- Home remedies can soothe the majority of coughs.
There are three phases to a cough:
- Inhalation (breathing in).
- Increased pressure in the throat and lungs with the vocal cords closed.
- An explosive release of air when the vocal cords open, giving a cough its characteristic sound.
If somebody coughs a lot, it can be a sign of a disease. Many coughs are caused by infectious diseases, like the common cold, but there are also non-infectious causes. We look at some potential causes in the next section.
The majority of coughs are caused by viruses and clear up without treatment.
Causes of acute (short-term) cough
In most cases, the infection is in the upper respiratory tract and affects the throat, this is known as a URTI or URI (upper respiratory tract infection). Examples include:
If it is an LRTI (lower respiratory tract infection), the lungs are infected, and/or the airways lower down from the windpipe. Examples include:
An acute cough can also be caused by hay fever.
Causes of chronic (long-term) cough
A chronic cough may be caused by:
- mucus dripping down the throat from the back of the nose (post nasal drip)
- GERD (gastro-esophageal reflux disease)
- some medications (e.g., ACE inhibitors)
Chronic coughs in children are most often caused by asthma, but can also be from conditions like post-nasal drip or GERD.
If a cough has persisted for 3 weeks without improvement, it is sensible to visit a doctor.
In most cases, there will not be anything serious underlying the cough, but in rare cases, a long-term cough can be a sign of something that needs treating, such as lung cancer or heart failure.
Other reasons to seek medical advice include:
- The cough is getting worse.
- There are swelling or lumps present in the neck region.
- Weight loss.
- Severe coughing.
- Difficulty swallowing.
- Permanent changes in the sound of the voice.
- Coughing up blood.
- Difficulty breathing.
- Chest pain.
- Fevers that are not getting better.
If a doctor decides that a cough is caused by the common cold or flu, the general advice will be to rest, drink plenty of fluids, and let it run its course. In the majority of cases, such coughs clear up after 1–2 weeks.
A cough caused by a viral infection that persists for more than a couple of weeks will probably require medical attention.
The doctor may order some diagnostic tests, such as a chest X-ray; a sample of phlegm may be sent to a laboratory for analysis to determine what is causing the infection.
The patient may be asked to breathe in and out of a tube attached to a machine; this helps the doctor determine whether the airways have an obstruction (this test is called spirometry), which is common in asthma or emphysema.
If asthma is diagnosed, the patient may be prescribed asthma medication.
Sometimes, a doctor might refer the patient to a lung or ear, nose, and throat (ENT) specialist.
The best way to treat a cough caused by a viral infection is to let the immune system deal with it — generally, such coughs clear up on their own.
If a doctor is treating a cough, they will focus on the cause; for example, if it is due to an ACE inhibitor, it may be discontinued.
Codeine, dextromethorphan, and other cough suppressants are often used by people with coughs.
However, there is not much research into cough medicines and how much they can actually reduce symptoms.
According to the National Health Service (NHS), United Kingdom, a homemade remedy with honey and lemon is as good, if not better than most over-the-counter (OTC) products sold in pharmacies.
Treatments are mostly aimed at making the patient feel a little bit better but generally do not decrease the length of the cough.
Honey — it coats the throat, resulting in less irritation and possibly less coughing. Honey is a demulcent (something that soothes).
Cough medications — some may help associated symptoms, such as fever or a stuffy nose. However, there is no compelling evidence that cough medicines are effective in making the cough go away faster. A variety of cough medicine is available for purchase online.
For small children, it is a good idea to talk to a doctor before giving OTC cough medicine. Some ingredients in cough medicines, such as codeine, can be dangerous for small children. There is no evidence that cough medicines help children, and they can actually be dangerous due to the side effects.
Cough suppressants — these suppress the cough reflex and are generally only prescribed for a dry cough. Examples include pholcodine, dextromethorphan, and antihistamines.
Expectorants — these help bring up mucus and other material from the trachea, bronchi, and lungs. An example is guaifenesin (guaiphenesin), which thins the mucus and also lubricates the irritated respiratory tract, helping to drain the airways. Cough expectorants are available to purchase over-the-counter or online.
In summary, coughs can be annoying and uncomfortable but, for the most part, they will clear up on their own. However, if a cough has continued for some time or got worse, it is still important to speak with a doctor.