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#229 Antispasmodics and peppermint oil: Old news or a breath of fresh air in managing Irritable Bowel Syndrome

Are antispasmodics (including peppermint oil) effective in treating irritable bowel syndrome symptoms?

Approximately 60% of patients report overall symptom or abdominal pain "improvement" on antispasmodics (including peppermint oil), compared to ~30-50% on placebo, with numbers needs to treat of 3-8.  Compared to placebo, adverse events occur for an additional 1 in 20 with antispasmodics and 1 in 11 on peppermint oil.

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3 Systematic Reviews:
  • 29 randomized controlled trials (RCTs), 2333 patients, various antispasmodics, including peppermint oil.1 Patient reported outcomes after 1 week to 6 months:
    • Overall "symptom improvement": 57% versus 39% placebo; number needed to treat (NNT)=6.
    • Abdominal pain "improvement": 58% versus 46% placebo; NNT=8
  • Older systematic review (13 RCTs, 1379 patients). Outcomes at 2 weeks-6 months similar.2 Adverse events (dry mouth, dizziness, blurred vision reported):
    • 14% versus 9% placebo; number needed to harm (NNH)=20.
  • Systematic review of peppermint oil alone (9 RCTs, 726 patients, 2-12 weeks duration).3
    • Overall "symptom improvement": 69 versus 31% placebo; NNT=3.
    • Abdominal pain "improvement": 57% versus 27% placebo; NNT=4.
    • Overall adverse events (including heartburn, dry mouth, peppermint smell/taste):
      • 22% versus 13% placebo; NNH=11.
Newest RCTs:
  • 712 patients randomized to hyoscine, hyoscine + acetaminophen, acetaminophen, or placebo for four weeks.4 Paper translated by TFP authors.
    • "Slight" or "significant" symptom improvement: hyoscine + acetaminophen=81%, hyoscine=76%, acetaminophen=72%, placebo=64%;
      • Hyoscine groups statistically better than placebo.
    • Adverse events: 5% overall.
  • 427 patients given pinaverium 50mg or placebo TID.5 After 4 weeks:
    • >30% improvement in abdominal pain: 62% versus 30% placebo; NNT=3.
  • 72 patients given peppermint oil tablets or placebo.6 After 4 weeks:
    • Mean reduction 4-point symptom score: ~1.2 peppermint oil versus 0.7 placebo.
Limitations: small studies,1,2 short durations,1 multiple/incomplete outcomes reported1,4, conflicts of interest/industry funding3,6, use of non-validated scales.6 Context:
  • Large placebo response often seen in IBS studies.7
  • Guidelines recommend considering antispasmodics8,9 or peppermint oil8 in IBS patients.
  • Antispasmodics in Canada include hyoscine, pinaverium, trimebutine, dicycloverine, peppermint oil.
    • Cost varies significantly
      • Peppermint oil ranges ~$60 to $360 for 3 months.10

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  • Amol Bhargava MD MSc
  • Michael R Kolber MD CCFP MSc

1. Ruepert L, Quartero AO, de Wit NJ, et al. Cochrane Database Syst Rev. 2011; 8:CD003460.

2. Ford AC, Talley NJ, Spiegel BMR, et al. BMJ. 2008; 337:a2313.

3. Khanna R, MacDonald JK, Levesque BG. J Clin Gastroenterol. 2014; 48(6): 505-12.

4. Schafer VE, Ewe K. Fortschr. Med. 1990; 25: 488-92.

5. Zhang L, Lai Y, Lu W, et al. Clin Gastroenterol Hepatol. 2015; 13:1285-92.

6. Cash BD, Epstein MS, Shah SM. Dig Dis Sci. 2016; 61:560-71.

7. Kaptchuk TJ, Friedlander E, Kelley JM, et al. PLOS One. 2010; 5(12):e15591.

8. Ford AC, Moayyedi P, Lacy BE, et al. Am J Gastroenterol. 2014; 109:S2 - S26

9. National Institute for Health and Care Excellence (NICE). 2017. Irritable bowel syndrome in adults: diagnosis and management. CG61.

10. 2018. Accessed Sept 3, 2018.

Authors do not have any conflicts of interest to declare.