This is a festive break from my usual offerings on emergency toxicology, although you will note I lapsed a bit with dextromethorphan. My last post was on the SNAP regimen in teenagers, and can be found here.
I am currently recovering from pneumonia. It is not pleasant. Like Tiny Tim himself, I have been struggling with a cough. And if the information I give in ED is correct, it will be weeks before I feel better.
Humbug 🙁.
To look after myself over this festive period, I did some research on cough remedies. The results were surprising. Practice-changing, even. So I thought, as an early Christmas present for the good readers of St Emlyn’s, I would collate my notes into a blog post. It could come in handy with our current influenza outbreak.
What does not work
There are a lot of cough medications on the naughty list, it would seem.
The biggest disappointment to me was codeine. It appears to be completely ineffective as an antitussive. Same with antihistamines, which are present in a number of over-the-counter treatments. These are definitely medications that I have prescribed or recommended for coughing patients in ED. I doubt I will do so again. I never liked the way their side-effects (e.g. nausea, dry-mouth) mix with seasonal infections.
Dextromethorphan was another let-down. For those unfamiliar, dextromethorphan is a cough suppressant found in syrups like Benylin® Dry. It is an NMDA receptor antagonist with theorised activity at the medulla. As a fun toxicological aside: this is why overdosing on dextromethorphan (“Robo tripping”) causes dissociative experiences. The mechanism in toxicity is identical to phencyclidine (“PCP”) or its derivative — ketamine! You have to drink unsettling amounts of cough syrup to make this happen, though. Would not recommend.
Anyway: the evidence for dextromethorphan as an antitussive is poor, which is a shame, because the side-effect profile is very favourable compared to, say, codeine. NICE, in 2019, found very little data to support its use in adults, and none in children. Since 2019, only one trial has been published on this topic, which found no reduction of cough duration with dextromethorphan in patients (n=194) with bronchitis.
There were two additional listings for RCTs: one in adults (n=52) finished in 2015 and another in children (n=128) halted early in 2020. No clinically significant benefit of dextromethorphan was reported in either.
Neither of these trials were published. Both were industry-sponsored. I will leave it at that.
What might work
I came across a wide range of medicinal plants that are reported to have benefit in cough. Ivy, primrose, thyme, Echinacea, Pelargonium… the list goes on. The evidence for most of these was mixed at best, and there were some suspect journals involved. Steer clear. One plant did stand out in the literature, and this was Andrographis paniculata:
Andrographis is native to south-east Asia but sold widely in capsule form by UK retailers. It is classed as a herbal supplement, but unlike most “natural remedies” its medicinal properties have been put to the test. A 2017 meta-analysis in PloS One covered eight trials on Andrographis, and found an improvement in both the severity and duration of cough compared to placebo. A follow-up review of studies conducted during the COVID-19 pandemic had more mixed results: the effect of the plant were pronounced in the early phases of infection, but dropped off after.
Would I recommend Andrographis to a patient in ED? Probably.
I would be hesitant if they were on a lot of regular medications, as, like many herbal treatments, Andrographis can interact weirdly with CYP enzymes. For everyone else, though, a once-daily dose of 400-500mg is unlikely to cause harm, and might help a bit.
What really does work
So it turns out, the cough suppressant with the strongest evidence base is a substance produced freely worldwide, with no involvement of the pharmaceutical or supplement industries. It is…
…honey!
Aside from being delicious, honey has a demulcent (“coating”) effect on mucous membranes, which reduces irritation in the upper airway. It also contains protease enzymes. These help to thin sputum, making it easier to cough out.
The main evidence in favour of honey comes from a meta-analysis published by the BMJ in 2021. Fourteen trials were included, all involving patients with upper respiratory tract infections. Honey was consistently found to improve cough severity and frequency, and was superior to a range of pharmaceuticals (!) including dextromethorphan.
Subsequent trials have reported similar findings in adults and children with upper respiratory tract infections. Less efficacy is seen with bronchitis. The results appear consistent regardless of the type of honey used – e.g. farmed versus wild product.
[I spoke with the brilliant Andy Mockridge, whose work with bees you can read about here. He recommends to buy as local as possible when it comes to honey – for sustainability reasons, and because it just tastes better…]
I have been recommending honey to ED patients for a while now, but only ever in a wishy-washy, home-remedy sort of way. That is all about to change. Honey has far more evidence in its favour than many of the treatments we give in ED! I will definitely be stressing this to my patients. If they are being admitted to hospital, I might even ask their family to bring a jar in.
How do we dose honey, though? Most of the trials above used 10-15ml between one and three times per day. This seems reasonable to me. I would probably tell my patients to have a tablespoon a few times a day and before bed, with additional doses if they feel it is helping. There is a theoretical risk of contamination with Clostridium botulinum, so honey should not be given to infants.
Some parting thoughts
Coughing is miserable. It is a source of suffering in ED that many clinicians (myself included!) know very little about. I see it as very similar to itch and nausea in this respect. These symptoms are often not our priority in a busy department, but they deserve acknowledgement, because they really matter to our patients.
Hopefully, this article has shown you that there are some effective therapies for your patients with cough. Give them a go! It is the season for sharing, after all.
Greg Yates
Further reading
Abuelgasim H, Albury C, Lee J. Effectiveness of honey for symptomatic relief in upper respiratory tract infections: a systematic review and meta-analysis. BMJ evidence-based medicine. 2021 Apr 1;26(2):57-64.
Anibasa FO. Effect of Honey on Cough Symptoms in Children with Upper Respiratory Tract Infection: A Randomised Controlled Trial: West Afr J Med. 2022 Sep 16; 39 (9): 928-934. West Africa Journal of Medicine. 2022 Sep 16;39(9):928-34.
Body R, Kaide E, Kendal S, Foex B. Not all suffering is pain: sources of patients’ suffering in the emergency department call for improvements in communication from practitioners. Emergency Medicine Journal. 2015 Jan 1;32(1):15-20.
Hu XY, Wu RH, Logue M, Blondel C, Lai LY, Stuart B, Flower A, Fei YT, Moore M, Shepherd J, Liu JP. Andrographis paniculata (Chuān Xīn Lián) for symptomatic relief of acute respiratory tract infections in adults and children: A systematic review and meta-analysis. PloS one. 2017 Aug 4;12(8):e0181780.
Llor C, Moragas A, Ouchi D, Monfà R, Garcia-Sangenís A, Gómez-Lumbreras A, Pera H, Pujol J, Morros R. Effectiveness of antitussives, anticholinergics, and honey versus usual care in adults with uncomplicated acute bronchitis: a multiarm randomized clinical trial. Family Practice. 2023 Apr 1;40(2):407-13.
Ouaamr A, Mouna M, El Hassane O, Aziz M, Yahya C, Katim A. Therapeutic effect of honey on acute respiratory infections in adults. Journal of Pharmacy & Pharmacognosy Research. 2024 12 (4) 647-658.
Prabhakornritta P, Waranuch N, Fuangchan A, Srikham K, Boonpattharatthiti K, Barnig C, Boonyasuppayakorn S, Pitaksuteepong T, Bhattarakosol P, Moulari B, Pellequer Y. Exploring the clinical effects of Andrographis paniculata-derived compounds, its extract, or derivatives for the treatment of COVID-19: a systematic review and meta-analysis. Frontiers in Pharmacology. 2025 Jul 31;16:1598255.
