(Over the past few weeks nearly half of all the patients I’ve seen in the ER have come seeking treatment for cough. Here’s a lightly edited version of last year’s post on the topic. Nothing works, and that’s not a bad thing.)
The typical adult can expect to develop 2 to 4 URIs (upper respiratory infections) annually. Included in this category are colds with nasal congestion, sore throat, and cough. Bronchitis is a term meaning “airway inflammation.” People who are coughing have bronchitis by definition, and there is nothing about this term that implies a need for antibiotics. More than 90% of cough illnesses are virally mediated, and multiple studies have confirmed that antibiotics fail to shorten the severity of cough or duration of symptoms. The CDC specifically states: “Routine antibiotic treatment of uncomplicated bronchitis is not recommended, regardless of the duration of cough.”
One of the reasons why so many people erroneously believe that antibiotics are indicated is simply due to a lack of understanding about how long a typical cough lasts. A meta-analysis of studies on cough found that the mean duration for cough was 17.8 days, with typical symptoms lasting between 15 and 28 days. So unless you’ve been coughing for more than a month, there is nothing unusual going on. Unfortunately, patients expect symptoms to last less than a week, and frequently visit a doctor when they persist longer. More than half of these visits result in the unnecessary prescription of antibiotics by physicians who should know better, reinforcing the false notion that antibiotics are needed to treat cough. So stop going to the doctor for a “Z-Pak” every time you develop a cough—stop it, stop it, stop it!
With that out of the way, let’s move on to cough medicines. Coughing is annoying; it hurts, it interrupts sleep, it makes us miserable. Cough is the leading symptom prompting visits to the ER during the winter months, but it’s also a protective mechanism that prevents an upper respiratory infection from becoming a lower respiratory infection (i.e. pneumonia). If there were a medicine that eliminated cough, I wouldn’t prescribe it. Without the ability to cough you’d quickly wind up a very sick cookie. I’m not sure there’s any advantage trying to undo with medicines the measures nature has spent hundreds of generations evolving us to do to protect ourselves.
If wheezing is a component of the cough then bronchodilators like albuterol can help, but offer no benefit for most. Steroids have no role in the routine treatment of cough.
How about expectorants to loosen secretions? The only one approved by the FDA is guaifenesin. It’s in virtually every cough medicine, both over-the-counter and prescription (e.g. Mucinex, Robitussin, Cheratussin, Guaiatussin, Delsym, Entex, Theraflu etc.), but that doesn’t mean it works. It’s a tall order to think that an orally ingested medicine actually gets into the airway. Here’s what has to happen: 1) The drug has to be absorbed intact and bypass liver metabolism on its way to the lung; 2) It has to be preferentially taken up by the lung and excreted into the airway; 3) Once in the airway, it has to worm its way into mucus to “thin” it out, thereby making it easier to cough up. If this seems unlikely, that’s because it is unlikely. Just to be fair, I emailed the makers of Mucinex asking if they have any data documenting that orally ingested guaifenesin ends up in expectorated sputum. Noting that such information was “not available,” they then assured me that Mucinex products “have gone through all the necessary approvals required by the Food and Drug Administration.” How’s that for a dodge?
You’d think with millions of Americans taking these medicines to the tune of $3.5 billion in annual sales, there would be a ton of studies showing they work. That isn’t the case. In a review of studies dating back to the 1970s, the Cochrane Collaborative was able to find just 29 random controlled trials on cough medicines, 11 of which yielded positive results versus placebo. Of these, cough medicine manufacturers sponsored two-thirds. Meanwhile, adverse medication reactions were reported in 21 of the trials. A teaspoon of skepticism, please.
As to guaifenesin, 2 studies from more than 30 years ago reported a mild benefit in symptom reduction, while a more recent study published in 2012 (sponsored by the makers of Mucinex) noted a trivial difference in cough severity versus placebo. Weak evidence for a weak drug.
What about cough suppressants like codeine and dextromethorphan (the “DM” in Robitussin-DM, Mucinex-DM etc.)? Again, there are only few trials. Codeine was no more effective than a placebo in the 2 trials in which it was studied. In 3 adult trials there was a trend toward symptom reduction with dextromethorphan, but none in 4 pediatric trials. In 2007, an FDA advisory committee recommended against the use of cough and cold medicines in children under the age of 6 due to a lack of efficacy and concern for side effects. Note: If they aren’t good for younger kids, they likely aren’t good for older kids or adults either.
What about antihistamines and decongestants? They have plenty of side effects and don’t work for cough. Antihistamines may potentially worsen the situation by drying secretions, making them harder to expectorate. Scratch these medications off your list.
Tessalon Perles (benzonatate) may help a little. But the drug is only available by prescription, and the benefit doesn’t justify the cost of a doctor’s office visit (and certainly not the cost of a trip to the ER).
What about cough drops or chest rubs? There is weak data to support the use of mentholated cough drops. The data is stronger for vapor rubs containing menthol, camphor, and eucalyptus oil (Vicks VapoRub contains all 3). The camphor component, however, is extremely toxic if ingested, and these products are not to be placed under the nose or used at all in kids under the age of 2. Not a whole lot of benefit here.
It’s interesting to note that all cough medicines work better than nothing, because there is a very strong placebo effect associated with their use. And this, in turn, is because there is a voluntary component to cough. It is possible to partially suppress a cough simply by telling yourself not to do it. An elegant paper published in 2010 explained why up to 85% of a cough medicine’s effects are likely placebo related.
So what do I do when I get a cough? First of all, I don’t take antibiotics, antihistamines, vitamin C products, zinc, or cough medicines. If I have a fever, I treat it with ibuprofen or acetaminophen. I drink lots of water, use a vaporizer in my bedroom at night, and take a teaspoon of honey 2 or 3 times a day. That’s right, honey! It’s cheap, natural, and in trials, has outperformed both placebo and dextromethorphan. Maybe try it in tea or a “hot toddy,” but straight up is fine. Turns out, your grandmother was right; all you need for most coughs is rest, fluid, and a bit of honey. To prevent transmitting a cough to others, wash your hands frequently and cough into your elbow (not your hands).
Finally, I should note that not all coughs are benign. You should see a doctor if your cough is productive of bloody or rusty-colored sputum, associated with persistent high fever, or shortness of breath at rest. Naturally, if you have heart or lung disease your threshold for seeing a physician should be lower.
For the rest of you (adults only), here’s a delicious hot toddy recipe from the All Recipes website (http://allrecipes.com/recipe/hot-toddy/): Mix 1-teaspoon honey
2-fluid ounces boiling water
1 ½-ounces whiskey
1-pinch of ground nutmeg
1. CDC, “Adult Appropriate Antibiotic Use Summary,” Centers for Disease Control and Prevention, www.cd.gov/getsmart/campaign-materials/treatment-guidelines.html.
2. M. H. Ebell et al., “How Long Does A Cough Last? Comparing Patients’ Expectations With Data From A Systemic Review Of The Literature,” Ann. of Fam. Med., 2013; 11, no. 1: 5-13.
3. S.M. Smith et al., “Over-the-Counter (OTC) Medications For Acute Cough In Children And Adults In Community Settings (Review),” The Cochrane Collaboration, The Cochrane Library, 2014, Issue 11, John Wiley & Sons, Ltd.
4. K. Schroeder, T. Fahey, “Systematic Review Of Randomised Controlled Trials Of Over The Counter Cough Medicines For Acute Cough In Adults,” BMJ, 2002; 324: 1-6.
5. P.V. Dicpinigaitis, “Currently Available Antitussives,” Pulmonary Pharmacology & Therapeutics, 2009; 22: 148-51.
6. H. Albrecht et al., “Patient-Reported Outcomes To Assess The Efficacy Of Extended-Release Guaifenesin For The Treatment Of Acute Respiratory Tract Infection Symptoms,” Respiratory Research, 2012; 13: 118.
7. R. Eccles, “Importance Of Placebo Effect In Cough Clinical Trials,” Lung, 2010; 188 (suppl.): s53-s61.
8. M. N. Shadkam et al., “A Comparison Of The Effect Of Honey, Dextromethorphan, And Diphenhydramine On Nightly Cough And Sleep Quality In Children And Their Parents,” J. of Alt. and Compl. Med., 2010; 16, no. 7: 787-93.
9. O. Oduwole et al., “Honey For Acute Cough In Children,” The Cochrane Collaborative, The Cochrane Library, 2014, Issue 12, John Wiley & Sons, Ltd.
One thought on “I’m skeptical about … cough medicines (revisited).”
I always enjoy reading the posts on this blog. They are always interesting and informative. I had no idea that symptoms normally last up to 28 days.