Irritable bowel syndrome (IBS) can be difficult to treat. There is no single treatment that helps all IBS symptoms. Consequently, GPs often need to treat the most troublesome symptoms individually or use a general treatment that will calm or reassure the patient.
It can be difficult to establish drug treatments for IBS since placebos are very effective in as many as 50% of patients. This raises the probability that belief and confidence might play more of a role than the pharmacological effect of the drug, and that more effort should be expended on promoting faith in certain treatments that have a low incidence of side effects.
It is not surprising that in the absence of pathology or cause, treatments tend to slip into and out fashion and may vary according to the preferences of particular doctors or patients. Most prescriptions are generic, though some patients may prefer and ask for a specific formulation.
Standard current treatment
Antispasmodics are commonly used for pain in IBS – the most commonly prescribed are mebeverine, peppermint oil and hyoscine. Some patients prefer the sustained release or enteric coated formulations of peppermint oil. Antispasmodics are rarely completely effective and patients with severe abdominal pain tend to come back, whereupon it is best to then use an alternative, such as alverine, instead of mebeverine. Buscopan is an anticholinergic drug that can dry up the mouth and have other atropine-like side-effects such as urinary retention, blurred vision and increased constipation. One of the most effective treatments for visceral pain is low dose amitriptyline (10mg), which is said to have a specific effect on pain pathways.
Ispaghula is the standard and most useful compound for constipation associated with IBS, alongside advice to increase cereal fibre, fruits and vegetables in the diet. Patients need to take sufficient fibre to soften the stool. By the time patients have come to us, however, they have often tried ispaghula or other types of soluble fibre from their pharmacist, and may have found that that symptoms of bloating and abdominal pain have got worse. So for recalcitrant or more severe constipation, it is worth trying some osmotic purgatives such as a macrogol. Senna is still used but has become very expensive.
The standard treatment is loperamide. It is very effective in most people although many find that it may increase symptoms of pain or bloating and prefer not to take it regularly. People with diarrhoea, complicated by symptoms of urgency, find imodium particularly useful when taken as prophylaxis before they have to go out somewhere. Diphenoxylate or codeine phosphate are alternatives, but rarely prescribed these days.
Antispasmodics are occasionally helpful, and probiotics may be useful for some patients (discussed later), but increasingly I tend to refer patients to our community dietitian, who will treat them with a diet low in carbohydrates, disaccharides and monosaccharides (a low FODMAP diet, discussed later).
When IBS is clearly associated with depression or anxiety, or a variety of other somatic symptoms, antidepressants can be very useful. Tricyclics such as amitriptyline are mildly constipating and are more useful in patients with diarrhoea. For those with constipation or pain, I might tend to try SSRIs, such as cipramil.1 Counselling and psychotherapy may also be helpful but access to therapists can be a problem.
Complementary therapists claim good results and are popular with patients, but few practices have direct access to alternative therapies.
What’s newly available?
IBS does tend to be a graveyard for new drugs, which have a habit of peaking and then falling out of favour. Drugs that act on serotonin receptors to inhibit bowel sensitivity, such as the 5HT3 antagonist alosetron, have either been withdrawn or restricted. There was a brief enthusiasm for 5HT4 agonists, such as cisapride, but this was withdrawn because of cardiac side effects.
The only one of this family of drugs that has survived is prucalopride, which has found a toehold for women with severe constipation, but is rarely prescribed. Other new drugs for constipation-predominant IBS, such as lubiprostone, have not yet become established. Linaclotide is the newest drug for constipation-predominant IBS, and the manufacturers claim it increases both colonic secretion and propulsion by an action similar to cholera toxin, while at the same time reducing visceral sensitivity and pain.2 Linaclotide has recently been approved as freely prescribable by the Sheffield Area Prescribing Committee, but we have little experience of it.3
A low FODMAP diet (see below) has become established in the last few years and is said to be particularly useful for patients with bloating and or diarrhoea.
What has fallen out of fashion and why?
There was a time not so long ago when doctors tended to believe that IBS and many other ailments of life were caused by lack of dietary fibre. That was until it was brought to a halt by the demonstration that coarse wheat bran could irritate the sensitive gut and make the symptoms of IBS worse.4 Soluble fibre that includes the storage polysaccharides from fruits and vegetables is much ‘kinder’ to the gut, but even that is threatened by the evidence that fructans and galactans (high FODMAPs) in some vegetables and fruits is making things worse.
Lactulose used to be the most frequently prescribed laxative, but like FODMAP foods, this is fermented to gas causing pain and bloating. Magnesium sulphate has also fallen out of favour as a laxative because of the high prevalence of side effects. Similarly, bisocodyl is rarely prescribed.
Codeine phosphate was one of the most commonly prescribed anti-diarrhoea medications. Many patients preferred it to loperamide because it was able to cross the blood brain barrier and induce a feeling of calmness. But that same property meant there was a potential for drowsiness and habituation. Diphenoxylate and atropine are rarely prescribed these days.
Special/atypical cases and their treatment
The symptoms of IBS that occur are non-specific indicators of bowel irritation and can therefore occur in other conditions that affect the bowel. In addition to coeliac disease, inflammatory bowel disease and some cases of cancer, which can be screened out using specific tests, there is also other causes for disturbances of bowel function that are less easy to diagnose and require specific treatments.
In patients with chronic diarrhoea, SeHCat tests often reveal evidence of bile acid malabsorption.5 In these patients bile acid sequestrants, such as colestyramine or colesevelam, can be very helpful.6
The mild inflammation associated with post-gastroenteritis IBS may respond to NSAIDs such as mesalazine, though this is an unlicensed indication.
Small intestinal bacterial overgrowth (SIBO) is considered a subset of IBS, more frequently in the United States, depending on how breath tests are interpreted.7 It can be treated with the broad spectrum, poorly-absorbed antibiotic, rifamixin, which also suppresses fermentation in the colon and might risk antibiotic-associated colitis.
Non-drug options and their evidence base
Recent research suggests that diets low in poorly-absorbed fermentable sugars (FODMAPs) can be very effective in treating patients with bloating and diarrhoea. Double blind rechallenge studies have shown a dramatic increase in symptoms, while low FODMAP diets show significant improvements compared with standard dietary treatment for IBS.8
Trials of some probiotics have tended to show an improvement in symptoms of IBS in some patients some of the time. NICE stops short of endorsement, but recommends that probiotics could be tried for a month and if unsuccessful another probiotic could be tried.9 One study has indicated that a specific transgalactan prebiotic, bimuno, can reduce symptoms of IBS.10
In my experience, most patients with IBS have something going on in their lives that seem to exacerbate their symptoms. Psychotherapy and counselling are often very useful, though patients can find it difficult to access these.11 Similarly, hypnotherapy has a strong evidence base in IBS, while many patients find complementary therapies very helpful.12,13
With the enormous public access to information via the internet, patient education and self-care have been widely recommended to deal with the burden of IBS care. Last year, the IBS Network published its comprehensive IBS self-care plan, which is available online as an information resource for everybody with IBS.14 With numerous illustrations, exercises, videos and audios, patient letters and links, this deals with the issues people with IBS want to know about – diagnosis, what else might it be, diet, stress, medical management, therapies, as well advice on how to manage the main symptoms, pain, bloating, diarrhoea and constipation and a unique symptom tracker.
Dr Marion Sloan is a GP with special interest in gastroenterology and women’s health in Sheffield
1 Vahedi H, Merat S, Rashidioon A. The effect of fluoxetine in patients with pain and constipation-predominant irritable bowel syndrome: a double-blind randomized-controlled study. Alimentary Pharmacology and Therapeutics, 2005;22(5):381-385
2 Chey WD, Lembo AJ, Lavins BJ et al. Linaclotide for irritable bowel syndrome with constipation: a 26-week, randomized, double-blind, placebo-controlled trial to evaluate efficacy and safety. American Journal of Gastroenterology, 2012;107(11):1702-12
3 Layer P, Stanghellini V. Linaclotide for the management of irritable bowel syndrome with constipation. Alimentary Pharmacology and Therapeutics, 2014;39(4):371-384
4 Spiller R, Aziz Q, Creed F et al. Guidelines on the irritable bowel syndrome; mechanisms and practical management. Gut, 2007;56:1770-1778
5 Rasmussen S N, Madsen JL. Bile acid malabsorption in patients with chronic diarrhoea: clinical value of SeHCAT test. Scandinavian Journal of Gastroenterology, 2003;38(8):826-830
6 Kurien, M., Evans, KE, Leeds JS et al. Bile acid malabsorption a differential diagnosis for patients presenting with diarrhoea predominant irritable bowel syndrome type symptoms? Gut, 2011;60:A160-A161
7 Corinaldesi R, Stanghellini V, Cremon C et al. Effect of mesalazine on mucosal immune biomarkers in irritable bowel syndrome: a randomized controlled proof-of-concept study. Alimentary Pharmacology and Therapeutics, 2009;30(3):245-252
8 Ford AC, Spiegel BM, Talley NJ, Moayyedi P. Small intestinal bacterial overgrowth in irritable bowel syndrome: systematic review and meta-analysis. Clinical Gastroenterology and Hepatology, 2009;7(12): 1279–86
9 Gibson P, Shepherd S. Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology, 2010;25(2):252-258
10 NICE. CG61: Irritable bowel syndrome in adults – diagnosis and management of irritable bowel syndrome in primary care. London: NICE; 2008
11 Silk, DBA, Davis, A, Vulevic, J et al. Clinical trial: the effects of a trans-galactooligosaccharide prebiotic on faecal microbiota and symptoms in irritable bowel syndrome. Alimentary Pharmacology and Therapeutics, 2009;29(5):508-518.
12 Lackner JM, Mesmer C, Morley S et al. Psychological treatments for irritable bowel syndrome: A systematic review and meta-analysis. Journal of Consulting and Clinical Psychology, 2004;72(6): 1100-1113
13 Kearney DJ, Brown-Chang J. Complementary and alternative medicine for IBS in adults: mind body interventions. Nature Clinical Practice. Gastroenterology and Hepatology, 2008;5(11):624-636
14 IBS Network. The IBS self-care plan. Sheffield: IBS Network; 2013
British Society of Gastroenterology. Chronic management – IBS/functional symptoms. BSG; 2009 Available at: http://www.bsg.org.uk/clinical/commissioning-report/ibs/functional-symptoms.html.