For patients with IBS-C, pharmacological therapies, including low-dose polyethylene glycol (PEG), low-dose lactulose and 5HT4 receptor agonist (prucalopride), have shown efficacy in symptom improvement and are recommended by GESA. PEG is an osmotic laxative that improves chronic constipation, although evidence is sparse on its efficacy in treating IBS-C.⁷ However, it is relatively safe withminimal side effects (bloating and flatulence) and thus can be trialled in patients with IBS-C. Similarly, low-dose lactulose can be used if there is no response to PEG, and is preferred over stimulant laxatives due to tolerance and the rare side-effect of an atonic colon with long-term stimulant laxative use.^41,42 Prucalopride has been shown to be effective in treating constipation and can be taken at 1 to 2 mg daily if other therapies fail. Possible adverse effects include headaches, nausea and abdominal pain.⁴³ Patients should be advised to stop treatment if there is no response at four weeks. 

Treatment of patients with IBS-M should be tailored to predominant symptoms and is largely based on the treatments for IBS-D and IBS-C; however, ensuring patients do not experience ‘pseudo-IBS-M’ due to use of laxatives or antidiarrhoeal agents is important.²² 

Conclusion 

The management of patients with IBS follows a longitudinal model of patient care, which takes into account the patient’s biopsychosocial context while addressing their gastrointestinal symptoms. As GPs have an established therapeutic relationship with their patients, they are uniquely placed to manage patients with IBS. Patients who present with alarm features, diagnostic uncertainty, or who have ongoing symptoms or concerns should be offered specialist referral.     MT