Issues for surgery
Reduction in intentional weight loss (due to increased dietary fat absorption) if omitted.
Potential problems with toileting in post-operative patient if continued.
Advice in the perioperative period
Elective surgery
Miss dose(s) of orlistat while the patient is fasting.
Emergency surgery
Miss dose(s) of orlistat while the patient is fasting.
Patients admitted with suspected cholestasis
Orlistat is contraindicated in patients with cholestasis and should be discontinued in anyone presenting with any signs or symptoms suggestive of cholestasis.
Patients admitted with rectal (PR) bleeding
There have been reports of rectal bleeding associated with orlistat use; patients admitted with severe or persistent PR bleeding should have this investigated further
Post-operative advice
If a meal is missed or contains no fat, the dose of orlistat should be omitted.
Due to gastrointestinal side effects (including faecal urgency, liquid stools, and faecal incontinence), patients may prefer to withhold orlistat as an inpatient, particularly if they are less mobile post-operatively.
Patients undergoing bariatric surgery
Use of orlistat should be reviewed following bariatric surgery.
Interactions with common anaesthetic agents
None.
Interactions with other common medicines used in the perioperative period
None.
However, orlistat might affect the absorption of concurrently administered drugs – consider separating administration, particularly with critical medications or drugs that have a narrow therapeutic index.
Further information
None relevant.
References
Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 19th April 2025]
Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 19th Aptil 2025]
Orlistat. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. Electronic version. Truven Health Analytics, Greenwood Village, Colorado, USA. Available at: http://www.micromedexsolutions.com. [Accessed 19th April 2025]
Summary of Product Characteristics – Xenical® (orlistat) 120mg hard capsules. Neon Healthcare Ltd. Accessed via www.medicines.org.uk 25/10/2025 [date of revision of the text October 2023]