For centuries, doctors and care givers have listened to the different types of cough in search of clues to help diagnose underlying disease.
Coughs are a valuable diagnostic tool, but how do you know if you’ve got a relatively harmless cough, a coronavirus cough – or something else altogether?
An occasional cough is healthy, but one that persists for weeks, produces bloody mucus, causes changes in phlegm colour or comes with fever, dizziness or fatigue may be a sign you need to see a doctor.
If you’ve gone to see a doctor about a cough, he or she will want to know:
how long has the cough lasted? Days, weeks, months?
when is the cough most intense? Night, morning, intermittently throughout the day?
how does the cough sound? Dry, wet, barking, hacking, loud, soft?
does the cough produce symptoms such as vomiting, dizziness, sleeplessness or something else?
how bad is your cough? Does it interfere with daily activities, is it debilitating, annoying, persistent, intermittent?
COVID-19 cough: dry, persistent and leaves you short of breath
The most prominent symptoms of COVID-19 are fever and fatigue, and you may feel like you have a cold or flu. Cough is present in about half of infected patients.
Considering that COVID-19 irritates lung tissue, the cough is dry and persistent. It is accompanied with shortness of breath and muscle pain.
As disease progresses, the lung tissue is filled with fluid and you may feel even more short of breath as your body struggles to get enough oxygen.
Wet and phlegmy or dry and hacking?
A wet cough brings up phlegm from the lower respiratory tract (the lungs and lower airways, as opposed to your nose and throat) into the mouth.
The “wet” sound is caused by the fluid in the airways and can be accompanied by a wheezing sound when breathing in. The lower airways have more secretory glands than your throat, which is why lower respiratory tract infections cause a wet cough.
A dry cough doesn’t produce phlegm. It usually starts at the back of the throat and produces a barking or coarse sound. A dry cough does not clear your airways so sufferers often describe it as an unsatisfactory cough.
Nose and throat infections cause irritation to those areas and produce a hacking dry cough with sore throat. These types of cough are often seen in flu or cold.
Sometimes a cough can start off dry but eventually turn wet.
For example, the lung infection pneumonia often begins with a dry cough that’s sometimes painful and can cause progressive shortness of breath. As infection progresses, the lung air sacs (alveoli) can fill up with inflammatory secretions such as lung tissue fluid and blood, and then the cough will become wet. At this stage, sputum becomes frothy and blood-tinged.
What about whooping cough?
Whooping cough is caused by bacterial infection that affects cells in the airways and causes irritation and secretion.
Symptoms include coughing fits that end in a loud, “breathing in” noise that often sounds like a long “whoop” and leaves you gasping for air. Mucus is often expelled.
As respiratory clinicians, we have been conducting outreach clinics to the Kimberley, in northern Western Australia, for about ten years, treating children with bronchiectasis, a chronic lung disease in which the breathing tubes in the lungs are damaged.
If left untreated, bronchiectasis can eat away at the lungs and cause devastating long-term effects.
Our research, published today in the journal Respirology, shows how Aboriginal health providers, visiting clinicians, and Aboriginal families can work together to detect illness that may lead to bronchiectasis as symptoms first appear, using local language, stories, and resources.
These resources, including an animated video, highlight that chronic wet cough, in the absence of any other symptom or sign, can be the earliest and often only warning sign of lung disease.
Why early detection is key
A persistent, low-grade wet cough is often a sign of mucus in the airway that has become infected. Over time, this mucus begins to destroy the lung tissue.
Limiting the extent of lung damage is predicated on timely recognition and management of the chronic wet cough. Treatment may include antibiotics and chest physiotherapy.
If left untreated, the disease can progress and result in a lot of coughing, feeling breathless, losing sleep, feeling worried and helpless, and, eventually, early death.
In Australia, lung infections are the most common reason Aboriginal children are hospitalised. Young Aboriginal children in WA are up to 13 times more likely to be admitted for lung infections than non-Aboriginal children.
More than a quarter of young Aboriginal children admitted with lung infections will go on to develop potentially life-shortening chronic lung disease.
Lung disease is a major contributor to the gap in life expectancy between Indigenous and other Australians. Indigenous Australians hospitalised with bronchiectasis die, on average, 24 years earlier than non-Indigenous Australians with the condition.
Each quarter, Perth Children’s Hospital sends a multidisciplinary team to see about 30 children, mostly Aboriginal, who have been referred for specialist care by doctors from across the vast Kimberley region.
We have witnessed the consequences of lung disease being diagnosed too late. We once treated an adolescent Aboriginal boy with end-stage bronchiectasis. He was so sick that he was unable to walk or lie flat. His lung function was less than 25%, well below the threshold for lung transplantation.
This boy was dying from an illness that could have been halted or reversed had someone treated him effectively before his disease had progressed this far. A note in his medical record stated: “Lost to the system.”
In our clinics, we noticed a high prevalence of Aboriginal children with lung disease who were seen too late, when preventable lung damage was already permanent.
We found we were not always eliciting accurate histories from families. Specifically, when we asked engaged parents if their children had a wet cough, the parents would say “no” when, in fact, the children did have a wet cough.
Accurate medical history taking is crucial to providing good medical care, as is the provision of culturally appropriate care. But we realised a barrier was preventing us from communicating effectively with families, and preventing those families seeking timely medical care for their children.
From mucus to goonbee
We addressed the issues through partnerships with Aboriginal families, researchers, Aboriginal health providers, and government. We identified the barriers and enablers for both families and clinicians to recognise and manage early lung disease and stop it progressing to serious life-limiting illness.
We interviewed 77 Aboriginal families and clinicians in the Kimberley, and discovered that families had never heard that a daily wet cough for more than four weeks could indicate serious infection.
Coughing was so prevalent among Aboriginal children that symptoms were being normalised.
When families were given culturally appropriate health information, they sought medical help. Parents also gave an accurate history about the presence of wet cough once they better understood the topic.
Culturally appropriate information included use of local language terms – such as goonbee for mucus in Yawuru language – and use of stories or images that families could relate to.
Clinicians can liken the lungs to an upside-down tree, for instance, where the tree trunk is the windpipe, the branches are the breathing tubes, and the leaves are the air sacs where oxygen is transferred to the blood.
We also developed culturally relevant educational resources for clinicians and families, including an animated film and an information flip chart.
Through collaboration, mutual respect, and knowledge translation in our clinics, we are now witnessing little lungs growing stronger, Aboriginal families empowered with knowledge and advocating for their children, and clinicians skilled to provide culturally informed care to children. These observations are being supported by research soon to be published.
By engaging and working together, we will find sustainable solutions to kick chronic wet cough and help prevent Aboriginal children with sick lungs from flying beneath the radar.
Nerve receptors throughout the lungs, and to a lesser extent in the sinuses, diaphragm and oesophagus (food pipe), detect the irritant or mucus. Then, they send messages via the vagus nerve to the brain. The brain, in turn, sends messages back through the motor nerves supplying the diaphragm, chest muscles and vocal cords.
This results in a sudden, forceful expulsion of air.
Your cough may be a one off. Alternatively, you can have a run of repeated coughs, especially in whooping cough, which people describe as a bout, attack or episode.
Which type of cough do I have?
There are many different types of cough but no one definition that everyone agrees on. This can be confusing as patients classify their cough in descriptive terms like hacking or chesty, while doctors classify them on how long they last: acute (under three weeks), subacute (three to eight weeks) and chronic cough (more than eight weeks).
Coughs can also be called wet or dry. Officially, you have a wet cough when you produce more than 10mL of phlegm a day.
For people with chronic coughs, their cough can further be classified after an x-ray — either with lung pathology to indicate something like pneumonia or tuberculosis, or without signs of underlying disease (an x-ray negative cough).
A wet cough is more common in people with sinus and chest infections, including influenza, bronchitis and pneumonia, and serious infections such as tuberculosis.
A smoker’s cough is usually wet, as the precursor to chronic bronchitis. As it progresses, or when complicated with infection, larger amounts of mucus may be coughed up daily.
Then there is a dry cough associated with a cold or flu that turns into a moist cough. People tend to describe this as “chesty” and it makes them worry the infection has moved to their lungs.
Yet mostly their lungs are clear of infectious sounds when examined with a stethoscope. Even a small amount of mucus stuck around the vocal cords or back of the throat may produce a moist sounding cough. But this is not necessarily a wet or “productive” (producing lots of mucus) cough.
One study showed even doctors struggled to make an accurate diagnosis based only on the sound of the cough. Their diagnosis of the cough was correct only 34% of the time.
People with upper airway cough syndrome may feel mucus secretions moving down the back of the throat, causing them to cough. New evidence suggests the cough is caused by the increased thickness of the mucus and slowness of that mucus being cleared by cilia (hair like structures in lining cells whose job is to move mucus along).
This mechanism keeps the chronic cough going through a feedback loop I call the “cough and mucus” cycle. In other words, the more the throat is irritated by the sticky mucus, the more you cough, but the cough is poor at shifting the mucus. Instead, coughing irritates the throat and fatigues the cilia, and the mucus becomes stickier and harder to shift, stimulating further coughing.
When coughing gets too much
Coughing is hard work so no wonder you can feel physically exhausted. In one study, people with asthma coughed as many as 1,577 times in one 24-hour period. But for people with a chronic cough, it was up to 3,639 times.
The high pressures generated in vigorous coughing can cause symptoms including chest pains, a hoarse voice, and even rib fractures and hernias. Other complications include vomiting, light-headedness, urinary incontinence, headaches and sleep deprivation. Chronic cough may also lead to people becoming embarrassed and avoiding others.
Is it true?
People still seemed surprised and worried when a cough persists after a cold and flu despite the fact cough outlasts other symptoms in most cases. When an Australian study followed 131 healthy adults with an upper respiratory tract infection, 58% had a cough for at least two weeks and 35% for up to three weeks.
Then there’s the colour of your mucus. Patients and doctors commonly interpret discoloured mucus, particularly if green, as a sign of bacterial infection. But there’s clear evidence that the colour alone is not able to differentiate between viral and bacterial infections in otherwise healthy adults.
Another study found that people with acute cough who coughed up discoloured phlegm were more likely to be prescribed antibiotics, but they did not recover any faster than those not prescribed antibiotics.
When and how should I treat my cough?
Due to the multiple causes and types of cough there is not room to cover this question adequately. A safe approach is to diagnose the disease that is causing the cough and treat it appropriately.
For chronic dry coughs and coughs that last after acute upper respiratory tract infections, the cough is no longer serving a useful function and treatments can be targeted at breaking the cycle of irritation and further coughing. The evidence for effective treatments is patchy, but cough suppressants, steam inhalation and saline nasal irrigations, as well as prescribed anti-inflammatory sprays may help.
A spoonful of honey reduces cough in children more than placebo and some cough mixtures. It is thought that the soothing effect on the throat is the way this works.
However, there is no good evidence for the effectiveness of commonly used over-the-counter medicine (cough medicine or syrup) to alleviate acute cough, yet they are still sold. Some contain drugs with the potential to cause harm in children, such as antihistamines, and codeine-like products.