Interviewer: All right. You have a chronic cough, Dr. Tom Miller, we're looking for some reasons why somebody might have a chronic cough or helping them diagnose themselves. First of all, I think we need to define what is a chronic cough.
What is a Chronic Cough?
Dr. Miller: That's a great question. So first of all, somebody who has a cough for more than eight weeks. And I should point out that worldwide, that's one of the major reasons people go to see a physician is because of a cough.
Interviewer: That's a biggie, huh?
Dr. Miller: Yeah, so we say chronic cough, by definition, is a cough that lasts longer than eight weeks. An acute cough occurs up to three weeks. And that usually occurs after an upper respiratory tract infection or viral infection that people get in the winter or spring.
Interviewer: Like a cold or something like that?
Dr. Miller: Like a cold, but that generally goes away by the end of three weeks. And then subacute is that period between three and eight weeks. But after eight weeks, you've got a chronic cough.
Interviewer: So in that gray area, three to eight weeks, I still shouldn't necessarily be concerned but at eight weeks, I should start looking for some causes?
Dr. Miller: Yeah, at eight weeks, I think it's sort of time to figure out why you might have that cough. And the good news is that 95% of the reason for that chronic cough is that can be figured out and there is a very good chance that treating it with the variable treatments that we have, depending on the cause, will make you better, make the cough go away.
Interviewer: Well, that's good news because there can be a lot of different causes, from what I understand, and tracking it down might be kind of tricky. But let's talk about the biggies.
Causes of Chronic Cough
Dr. Miller: Well, smoking is one of them. I think let's just talk about that right up front. So if you smoke and you have a cough, the first thing we tell people is you've got to stop smoking and if you stop smoking, it might take up to four weeks for that cough to go away.
Interviewer: So if I'm not a smoker and I still have this chronic cough, what are some other possibilities here?
Dr. Miller: Other possibilities would be cough due to post-nasal drip that goes on. Some people don't even they have post-nasal drip. I mean, some people will have a lot of sinus congestion and blow their nose or they'll have that sensation of postnasal drip that is fluid going down the back of your throat, so that's kind of gross, but that does trigger the cough receptors in the upper airways, causes a cough. In fact, that's probably the most common cause of chronic cough after eight weeks.
Interviewer: And that's one, like you said, you might not even realize what's causing it because you don't even realize you have it, necessarily.
Dr. Miller: Yeah, you might not know you have it. So the other two major causes, one is reflux. So if you have . . .
Interviewer: Like acid reflux in the stomach?
Dr. Miller: Acid reflux . . .
Interviewer: It can cause a cough?
Dr. Miller: It can cause a cough. Why is that? Because you have cough receptors in your esophagus that can be triggered and can produce a cough. And a lot of times, people don't even know they have reflux, though the reflux is the cause of the cough. And then the final category is what we call cough-variant asthma. And sometimes 25% of people who have cough-type asthma, they don't know they have asthma. That is they don't have wheezing or shortness of breath and sometimes you need to do some provocative testing to sort that out. So those are kind of the three major causes of cough outside of smoking.
Now, the first thing I'd tell you is if you have a cough that lasts longer than eight weeks, the first step is to see your doc and get a chest x-ray and make sure it's nothing else. Because we want to rule out the serious causes of cough, which, while they're rare, you want to pick them up and make sure you don't have those things. So infections, rare cases, tuberculosis, especially among immigrants or people who have been traveling in tuberculosis endemic areas.
Certainly, any other problems like somebody who's smoking and they're older, if they have a chronic cough, especially if it's productive or blood-streaked, we want to make sure they don't have a cancer. But beyond that, most of the causes of cough are benign. I shouldn't say benign, we know the causes and they can be treated, and in many cases, the cough goes away. Most cases.
Interviewer: All right, and just for fun, name some of the less known causes that it could be. Like something that I might not expect would be a cough.
Dr. Miller: One of the funny ones you'll see occasionally in practices, someone will have a hair in their ear that is touching up against the eardrum, that will . . . because you have a nerve that travels through the tympanic membrane, and if that hair is touching that nerve, it'll cause a cough. And that's a strange one, but that's also one of the reasons in patients who have chronic coughs, we look in the ears with an otoscope to make sure they don't have any obstructions in there. And sometimes in kids, you'll find actual little things they'll put in their ears that press against the tympanic membrane and cause a cough.
Interviewer: That's fascinating. I'm looking at some information here. I mean, there are a whole bunch of different things. So after you get rid of the biggies, then you would start looking at some more of those things. But would a specialist do that at that point?
When to See a Doctor for Your Cough
Dr. Miller: I think there are some rare causes that are probably not really worth going into that if you try the standard treatments for the three major causes, and stop smoking and your cough didn't go away, yeah, they would look into some of these rare causes.
Interviewer: So the good news is if you have a chronic cough and you've been to a physician a couple times and you're still not finding it, 95% of the time, it can be found eventually.
Dr. Miller: And the treatments, we probably should talk a little about the treatments because treatments need to be trialed for not a week or two weeks, but sometimes longer than that. As I mentioned before, people who stop smoking, it may take up to four weeks before that cough stops.
The other thing you should notice, sometimes smokers who quit smoking will cough even more after they quit smoking and that's because cough receptors start to grow back as the lining of their air tubes heals. And when that occurs, they start coughing more so they thinking quitting is making them worse. You've just got to tell them upfront that it might get better initially, but if it doesn't, hang in there. But by four weeks, their cough should be reduced. Now remember, you're going to get a chest x-ray first to make sure nothing else is going on before you advise them to wait it out for four weeks off cigarettes.
The next thing is with the cough-variant asthma, that probably requires testing in a pulmonary lab. And so that is something the physician can direct the patient to do and then they'll look at the results of that. They have some provocative testing so that if you don't have other symptoms of asthma, such as wheezing or shortness of breath, if you have cough-variant asthma, they can figure that out with testing. And then the treatment is usually the standard treatment we use for asthma.
For patients who have reflux cough, we put them on an eight-week or two-month trial of antacids, powerful antacids. And so we don't even expect to see results in a month. Usually, it'll take at least two months to see if that therapy is going to work. So you don't want to give up early on the treatments.
And then, the final category would be this post-nasal drip, which we said was probably the most common cause of chronic cough. And we can use either antihistamines or decongestants to clean that up. And there are also nasal steroids. So working with your physician to try to define the best treatments for the post-nasal drip will usually resolve the cough.
Interviewer: So generally, if it's not the biggies, there is something that can be done to find out what the cause is. Treatment might take some time as well, after that eight weeks. So I mean, we're looking at maybe 12 weeks before you know whether or not . . . you come in at eight, another four weeks to see if what you've treated . . .
Dr. Miller: That's a good point.
Interviewer: So it could take some time. Just be patient.
Dr. Miller: You have to be patient and work with your physician. Again, 95% of the time, we'll figure out what it is and treat it, and it'll go away.
updated: January 20, 2023
originally published: July 12, 2016
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