A niggling, nagging cough. They’re unpleasant, aggravating and — unfortunately — all too common after various viral infections.
Research suggests “post-infectious cough,” referring to symptoms lasting between three and eight weeks, impacts up to a quarter of adults after an initial respiratory infection like a cold, flu or COVID.
So how do you kick that kind of lingering cough for good?
In many cases, it’s just a matter of patience and time, suggest a trio of physicians in an article published in the Canadian Medical Association Journal (CMAJ) on Monday.
“Most of the time the cough will resolve on its own without any medication or treatment, but it can last a lot longer than you think,” said one of the article’s authors, Vancouver-based family physician Dr. Kevin Liang, in an interview with CBC News.
Liang, a clinical instructor in the department of family practice at the University of British Columbia, said patients often seem worried about their long-lasting coughs, thinking they still have their initial infection.
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But that’s usually not the case, he stressed.
What’s actually happening is that a preceding infection triggers an “inflammatory cascade,” Liang and his colleagues wrote, which then increases bronchial sensitivity and mucus production, while reducing mucus clearance.
In other words: Inflammation leads to more snot in your nose and more sensitivity in parts of your lungs, and that combo causes your body to cough — over and over.
And there’s no quick fix, Liang said.
Length of lingering cough matters
The question of how to combat an irksome cough is an old one.
For years, physicians divided up coughs into two categories: Acute, as in short-term, and chronic, referring to any cough lasting beyond a few weeks. But more recently, guidance started to shift toward a third category of “subacute” coughs that last just three to eight weeks — short enough to resolve, but long enough to be highly annoying.
One study, published nearly two decades ago, evaluated nearly 200 patients with lingering coughs, and found the most common cause of a “subacute” cough was simply a prior infection, not a more serious, ongoing health issue.
That’s the same conclusion in the new CMAJ article. But the Canadian physicians’ peer-reviewed practice suggestions also stressed that it’s important for clinicians to consider other possibilities.
For someone’s lasting hacking to be deemed a post-infectious cough, doctors need to confirm an earlier respiratory infection. They also need to rule out other health issues that can trigger similar symptoms, such as asthma, chronic obstructive pulmonary disease (COPD) or pertussis, a condition better known as “whooping cough” for the distinctive whoop sound it can lead to.
Certain red flags — and a cough lasting beyond eight weeks — should also prompt more follow-up, the physicians wrote.
Symptoms such as coughing up blood, difficulty swallowing and hoarseness, or a history of recurrent pneumonia or being a long-time smoker, can mean there’s another health issue at play.
In those cases, a lasting cough “may be a manifestation of something that needs treating more aggressively,” noted pulmonologist Dr. Imran Satia, who runs a cough clinic through McMaster University in Hamilton, Ont. and wasn’t involved in writing the CMAJ article.
If someone’s cough keeps getting worse, or if a patient has a fever, challenges breathing or constant wheezing — those are other signals that someone may have another underlying health condition, he said.
“There is significant nuance in how to manage this,” Satia stressed, since a persistent, longer-lasting cough can be a symptom of conditions as diverse and serious as lung fibrosis, lung cancer, heart failure or tuberculosis. “It is important that these are not missed,” he said.
But in straightforward cases where a previous viral infection has led to a lingering cough, physicians agree they usually resolve on their own.
‘No evidence’ treatments help
The catch is that it does take time. And there’s “no evidence” that treatment options help, the authors wrote in their CMAJ article.
The systematic research the group cited was published in the British Journal of General Practice in 2018 and looked at six randomized controlled trials featuring hundreds of patients with subacute coughs — which suggests there are no clear benefits to any treatment.
“Systematic reviews of randomized controlled trials evaluating inhaled corticosteroids, bronchodilators and oral agents for post-infectious cough concluded there is no evidence of benefit,” the CMAJ writers noted.
“Most trials found cough symptoms improve without medication, highlighting the self-limiting nature of post-infectious cough.”
Commonly-offered options such as inhalers and codeine can be expensive, Liang added, and they can come with “nasty side effects.”
Codeine — an opiate-based painkiller — is found in certain cough syrups, for instance, and when taken at high doses, it’s linked to drowsiness, headaches, slowed breathing and even nausea and vomiting.
Most inhalers, meanwhile, are the main type of therapy for chronic lung diseases such as asthma and COPD, rather than short-term cough concerns.
Antibiotics also don’t work; they’re used to combat active bacterial infections, not viral infections or post-infection inflammation. (Physicians also fear they’re being prescribed far too often, leading to rising rates of drug resistance, where bacteria evolve to evade our existing medications — causing untreatable infections.)
Satia agreed those options don’t make sense for run-of-the-mill hacking. “There is not much evidence to suggest that inhaled steroids, bronchodilators, antibiotics or steroids will help reduce cough and make you feel better.”
So is there anything people can do to mitigate weeks-long post-viral coughs?
In a lot of cases, Liang said patients’ hacking flares up at night, so he often recommends propping up a few pillows rather than sleeping flat in bed. But beyond that, it’s mostly just a waiting game.
“At the end of the day it really is time, ultimately, that is what is going to stop and solve that cough.”