Coughing’s reputation, it’s probably fair to say, has taken a bit of a hit. Once an occasional irritation, it recently spent a couple of years as a key symptom of a disease that everyone was worried about, and it has never entirely recovered. Cough on a train in 2021, and a decent chunk of the carriage would look at you as if you should be hermetically sealed in a bag. Do it now, and you may get away with a couple of nasty stares. But, Covid aside, what else might be causing that cough? And is there anything, realistically, you can do about it? “Coughs are a commonly presenting complaint, but in the vast majority of cases they’re nothing to worry about,” says Dr Timothy Gatheral, a consultant respiratory physician at the University of Lancaster. “As a consultant, I have a different perspective, as most cases I see have advanced to something more concerning, but the general NHS advice is not to worry unless you have a cough that persists for more than three weeks, or worsens very abruptly.” It is worth pointing out at this stage that coughing is actually an important part of the body’s defence against disease. It is a natural reaction to getting something stuck in the throat – a sudden-onset cough can often be from an obstruction you didn’t notice on its way down – and it also expels mucus, microbes and foreign particles from the respiratory tract, protecting the lungs. In some cases, excess coughing can actually lead to … more coughing, as the nerve that controls this coughing reflex becomes hypersensitive, which is one reason that it’s helpful to keep short-term coughs in check with hot honey water or sugar-free sweets. Most short-term coughs are caused by colds or flu, although heartburn, allergies, or infections can all play a part. But again, unless you’ve had one that lasts, it is unlikely to be a signifier of anything serious. Technically, even smoker’s cough can be a temporary issue, caused when the chemicals you inhale from smoking damage the small hairs – known as cilia – lining your airways, as well as causing inflammation and a buildup of mucus. Stop smoking, and it should improve – although other issues caused by lighting up won’t. One of the most common issues signified by a prolonged smoker’s cough, for instance, is chronic obstructive pulmonary disease (COPD), the technical term for a whole group of lung conditions that cause breathing difficulties. “Exposure to cigarette smoke can cause COPD, but so can certain types of dust and chemicals,” says Dr Gatheral. “Asbestos is the one that everyone worries about, but silica dust is increasingly an issue for builders and fitters, as people have their kitchens done.” Smoking-related COPD won’t go away if you give up tobacco – but at least it shouldn’t worsen. Another cause of COPD and other conditions, of course, is pollution: globally responsible for around one in six premature deaths worldwide in 2019, it’s worsening in many areas of the UK even as the WHO lowers its recommendations for allowable legal limits. If you’re able to choose when you go out, the Department for Environment, Food & Rural Affairs keeps a five-day forecast for UK levels online; if you can’t avoid the most polluted times, then try to stay away from main roads or at least to the inside of the kerb. Finally, if you have a cough that won’t go away, that worsens abruptly, or that appears alongside other symptoms such as breathing difficulties, unexpected weight loss, or even spots of blood, that’s the time to seek medical help – and be persistent about it. Conditions such as lung cancer or pulmonary fibrosis aren’t easy to treat, but they can be managed. “I don’t want people to worry unnecessarily, but there are times when it’s important to push,” says Dr Gatheral. “Most coughs will resolve on their own, but you know your own body, and if there’s something seriously wrong then it’s crucial that you get it checked out and, if possible, treated, sooner rather than later.” Coughing is mostly good for us, a biological adaptation that stops us from swallowing stuff or expels unpleasant material from our airways. Sometimes, though, it’s a marker of something worse.