In an effort to make science and healthcare information accessible, Carbon Health has partnered with Rob Swanda, PhD to answer questions about health science related topics, from actual people (via Dr. Swanda’s Twitter followers). Dr. Swanda is joined by Dr. Aaron Weinberg, the national director of clinical research at Carbon Health, to discuss a few questions related to lingering coughs.
Dr. Swanda: “What even is post-infectious cough syndrome?”
Dr. Weinberg: “Sure thanks for having me Dr. Swanda. Lingering cough or post-infectious coughs, I think we've all experienced this. It's usually that cough that continues and triggers those embarrassing stares in public after a respiratory infection, and you just can't seem to kick it. You get the family or friends comment 'are you sick?' 'should you be getting that checked out?'. It reminds me of that famous quote "love and cough cannot be hid". It's definitely unfortunately outwardly visible and audible. So what is post-infectious cough? The term usually refers to a cough that lingers three to eight weeks after a respiratory infection and sometimes that respiratory infection can be viral due to a virus, or due to bacteria. Some common viruses that tend to trigger this are the flu, RSV is another one which is circulating now as well as the flu, and covid-19 has also been linked to this. In addition certain bacteria can cause Post-infectious cough; mycoplasma is a kind of bacteria as well as bordetella, which can trigger these lingering coughs. It's a common condition, something I used to see all the time in my pulmonary practice.”
Dr. Swanda: “Now you mentioned several different viruses that we know can typically affect people at certain times during the year, so do we see any type of seasonality with post-infectious cough syndrome?”
Dr. Weinberg: “It can really happen any time of the year after any kind of infection. However, in the winter months we tend to see more circulating viruses, people tend to be inside more due to the weather (ie: family gathering), so you may be more likely to get infected by certain viruses. That may be why we see a clustering around this time of year, but it certainly could happen in the summer months too.”
Dr. Swanda: “Why exactly does post-infectious cough syndrome occur?”
Dr. Weinberg: “There are potentially different reasons for why this lingering cough occurs, one of the main drivers we think is inflammation. They've done procedures called bronchoscopies and biopsies where they've gone down into the lungs with a thin camera and taken samples of the lining of the lungs and they found a lot of inflammation in those samples. They've also found that the epithelial lining of the airways, which are cells that line our airways, tend to be disrupted in these conditions too. So, you don't have a smooth lining of cells, you have inflammation there and this can lead to increased sensitivity in the airways. Sometimes nerve roots are exposed and that can also lead to irritation and that reflexive cough. You also have something that occurs where you don't clear your mucus as effectively. There are these little tiny hair like structures that line our airways called cilia and they're almost like the fibers of a brush, and they help our airways clear mucus that forms due to infection, and those can get destroyed sometimes by the inflammation and the infection and they don't work as effectively, so you end up having a lot of mucus in your airways and you just can't get rid of it very effectively. To kind of summarize I would say it's due to inflammation disruption of the lining of the airways as well as maybe this cilia dysfunction and you just can't clear the mucus out.”
Dr. Swanda: “Besides the damage that could happen to your epithelial cells, what other contributing factors could play a role in lingering cough?
Dr. Weinberg: “There's also a thought that there could be upper airway or sinus involvement. Just as your lungs can get inflamed from infection, so can your sinuses, and the upper part of your airway. That can lead to increased mucus production. You may get a phenomenon known as post-nasal drip where some of that mucus ends up dripping down the back of your throat, irritating it and causing cough. And, lastly when you're coughing a lot that increases the pressure in your abdomen and that can lead to then further issues such as acid reflux or gerd where you end up, due to that coughing pressure, regurgitating some of your stomach acid back up into your esophagus and then up into your upper airway. That can also lead to irritation and chronic coughing.”
Dr. Swanda: “Now that we know what causes this condition, I have two questions. One, can this even be treated, and if so, how could it be treated?”
Dr. Weinberg: “Yeah it can be treated. There are certain therapies, however first and foremost you know it really follows the common saying that ‘time heals all wounds' and this applies to this condition. Most of the time it's self-limited, it improves with patience and time. I do empathize though with your viewers who have experienced this. Lingering cough can be extremely bothersome and frustrating, however I want to reassure people that with time it does get better. Sometimes you may choose to see a doctor for this and they may elect to do an x-ray because they want to make sure that there isn't anything else going on or anything more concerning that may contribute to the cough.. Most of the time this is no longer due to an infectious organism so antibiotics are generally not indicated. There is however a type of infection that can linger that should be treated and that's known as bordetella pertussis or whooping cough you may have heard of, and that can produce this hacking cough where you get these paroxysms of numerous coughs in a row followed by a high-pitched whoop sound at the end, that's where the name whooping cough comes from. Sometimes people get vomiting that's triggered by these episodes, so if you're displaying those signs or symptoms that may be concerning. For that kind of infection your doctor may end up prescribing antibiotics in addition if they feel like you have a chronic sinus infection that's also playing a role they may prescribe antibiotic for that, but generally speaking, antibiotics are not a mainstay treatment for this and if something isn't infectious you don't want to over prescribe antibiotics because it can actually lead to more resistance and more problems down the road. There's other things that people do sometimes that can have a benefit. Sometimes inhalers can be prescribed, one of them is known as ipratropium inhaler. Sometimes someone might prescribe a steroid inhaler. Again it's to try to open up the airways more effectively and decrease some of the inflammation that occurs in them. And, very occasionally if you have a severe cough, a clinician may prescribe a short course of oral steroids, however generally that's not needed unless it's severe. Other remedies people can try are cough drops, over-the-counter cough suppressants such as dextromethorphan and there's also Tessalon Perles, humidifiers, or tea with honey. Lastly, like I mentioned earlier if you do have that acid reflux or that burning in your esophagus that may be contributing sometimes an antacid can help, taking H2 blocker or a PPI can sometimes be beneficial as well.”
Dr. Swanda: “Besides the treatments that you had just listed, is there anything else that you may recommend as you've seen this condition with your own patients in the past?”
Dr. Weinberg: “If you're having a lot of upper airway nasal congestion or sinus congestion that may be causing post-nasal drip and contributing to chronic cough, there may be a role for oral antihistamines or also nasal sprays. Sometimes you can do an anti-inflammatory or antihistamine nasal spray, as well as saline flushes which can help if post-nasal drip is playing a role.”
Dr. Swanda: “And, we're hopeful that time would help someone relieve their symptoms of this lingering cough, but if someone's conditions are not improving what could they do?”
Dr. Weinberg: “If someone is not improving, especially after eight weeks, they probably should visit either their primary care provider or a pulmonologist to get it evaluated further and look into other causes of a chronic cough because generally speaking this lingering cough tends to last between three to eight weeks, so beyond that you really want to get a further evaluation. I would also say, if you have any concerning features even before those eight weeks such as trouble breathing, coughing up blood, if you start to have persistent fevers, or weight loss these should all be signs that maybe you need to get this looked into a little bit earlier just to make sure it's not a more concerning condition. But, the good news is that most people recover just fine with time so although it's easier said than done I encourage everyone to be patient with yourselves and seek out some of the symptomatic remedies I mentioned to help you get through this unfortunately annoying time.”
Check out the video conversation posted on January 16, 2023.
Rob Swanda, PhD is an mRNA biochemist and science communicator who obtained his PhD from Cornell University in 2021. Follow Rob Swanda, PhD on Twitter: @ScientistSwanda
Dr. Aaron Weinberg is the national director of clinical research at Carbon Health with a background in pulmonary critical care and internal medicine. Follow Dr. Aaron Weinberg on Twitter: @AaronWeinbergMD