Orlistat vs Saxenda in Australia

One randomised trial has compared liraglutide 3 mg with orlistat 120 mg: Astrup and colleagues, Lancet, 23 October 2009. It enrolled 564 adults aged 18 to 65 with a BMI of 30 to 40 and no type 2 diabetes at 19 European sites for 20 weeks, assigned to one of four liraglutide doses (1.2, 1.8, 2.4 or 3.0 mg once a day by injection, 90 to 95 people per dose), placebo injection (98 people) or orlistat 120 mg three times a day (95 people). Everyone followed a 500 kcal a day energy-deficit diet and increased physical activity.

Orlistat blocks absorption of about a third of the fat in a meal; its adverse effects are that fat passing through. Liraglutide, a GLP-1 receptor agonist injected daily, acts on appetite and slows stomach emptying; its adverse effects are mostly nausea and other gut symptoms. Figures are from the Australian Product Information for orlistat (the Orlistat Viatris document, which reports the Xenical trials; no Xenical-branded document is on Medsinfo) and for Saxenda (revised 26 June 2026; the generic pens carry the same indication).

Orlistat: oily spotting, flatus with discharge, faecal urgency, fatty or oily stool, flatulence, abdominal pain, oily evacuation, liquid stools, increased defecation and faecal incontinence are listed as common or very common. They occur mostly in the first three months, most people have one episode, 3% have more than two episodes of any one effect, and they worsen with the fat content of a meal. In year one of controlled trials 8.8% stopped for adverse events against 4.9% on placebo. The Australian document gives categories, not percentages; the US label, reporting the same seven trials, gives oily spotting in 26.6% against 1.3%, faecal urgency 22.1% against 6.7% and faecal incontinence 7.7% against 0.9%. Common effects (1 to 10%) also include soft stools, nausea, dyspepsia, headache and weakness. Very rare post-marketing reports include hepatitis and severe liver injury (some fatal or needing transplant) with no causal link established, pancreatitis, and oxalate kidney damage that may lead to renal failure.

Liraglutide: in the pooled Saxenda trials (3,384 on liraglutide, 1,941 on placebo) nausea occurred in 39.3% against 13.8%, diarrhoea 20.9% against 9.9%, constipation 19.4% against 8.5%, vomiting 15.7% against 3.9%, injection site reactions 9.0% against 1.7% and gallstones 1.5% against 0.5%; gut effects were mostly mild to moderate, started in the first weeks and settled within days or weeks. 9.8% stopped for adverse reactions against 4.3%. Warnings cover a rise in resting heart rate, pancreatitis, gallbladder disease, acute kidney injury after fluid loss, thyroid C-cell tumours in rodents, the GLP-1 class warning on suicidal thoughts (TGA, December 2025) and aspiration under anaesthesia (August 2025). The June 2026 revision added the optic nerve condition NAION, hair loss and abnormal skin sensation as post-marketing effects.

Orlistat 120 mg is Schedule 3 under the Poisons Standard (June 2026 instrument): a Pharmacist Only Medicine, supplied by a pharmacist without a prescription. Any other orlistat preparation is Schedule 4. No 60 mg product exists in Australia; Alli 60 mg was cancelled from the register at the sponsor's request on 22 June 2021. Healthdirect lists Xenical in packs of 9, 21, 42 and 84. Online, Chemist Warehouse requires a call to its pharmacists within five business days or the item is removed from the order; Chemist Outlet requires a call within 48 hours unless a prescription is supplied and limits orders to one pack; Your Discount Chemist labels the product "Prescription Only Medicine", will not dispatch without a script and limits orders to two. The Product Information criteria the pharmacist works from: a BMI of 30 or more, or 27 or more with other risk factors, with a mildly reduced-energy diet; one capsule with each main meal, during or up to an hour after, omitted if the meal is skipped or has no fat.

Liraglutide 3 mg is Schedule 4 and needs a prescription. The registered criteria, identical for Saxenda and the generic pens: a BMI of 30 or more, or 27 to under 30 with at least one weight-related condition such as prediabetes, type 2 diabetes, high blood pressure, abnormal lipids or sleep apnoea, with a reduced-calorie diet and more physical activity. Dosing starts at 0.6 mg a day and rises by 0.6 mg each week to 3 mg. The pens are kept at 2 to 8 degrees; Your Discount Chemist gives that as its reason for selling the line in store only, and Chemist Warehouse also lists it as unavailable online. Telehealth providers were not checked for this page. Whether a pharmacist may dispense a generic pen against a script written for Saxenda was not established in this research.

Liraglutide 3 mg produced more weight loss than orlistat in the only trial that tested both, and the 2016 network meta-analysis points the same way at one year (5.3 kg against 2.6 kg more than placebo). It costs about twice as much a day, needs a script and a daily injection kept in the fridge, and causes nausea in four in ten people. Orlistat's side effects are oily stools and faecal urgency that track how much fat you eat, and it interferes with a longer list of medicines. The April 2025 RACGP journal review recommends incretin medicines first where someone has type 2 diabetes, cardiovascular disease, sleep apnoea, fatty liver or knee osteoarthritis, and says orlistat can be considered for people with cardiovascular disease or hypertension where incretin medicines are not tolerated or unaffordable. Australian Prescriber (April 2022, by an author who declares advisory roles with the makers of liraglutide and semaglutide) says orlistat does not reduce hunger and so has no role in keeping weight off.

No Australian guideline covers moving between liraglutide and orlistat in either direction, and neither Product Information names the other medicine. Both advise against taking the two together: the orlistat document says use with other anti-obesity agents is not recommended in the absence of interaction studies; the Saxenda document says it is not recommended with other medicines intended for weight loss, prescription, over the counter or complementary, and should not be used with another GLP-1 medicine.

For people who were on Saxenda, Novo Nordisk's May 2025 letter asked prescribers to discuss alternatives, naming Wegovy 2.4 mg, with no dose mapping. A generic liraglutide 3 mg pen is the same molecule, dose and registered indication; ARX-Liraglutide is the one found on sale. No patient-facing Novo Nordisk notice from December 2025 was found.

Liraglutide after orlistat starts at 0.6 mg and steps up weekly; the document gives no shortcut. Orlistat after liraglutide has no guidance in either document. Regain after stopping liraglutide is documented: in SCALE, people switched to placebo after 56 weeks regained 2.9% of body weight within 12 weeks while those who continued lost a further 0.7%; a January 2026 BMJ meta-analysis across weight-loss medicines (37 studies, 9,341 people) put average regain at 0.4 kg a month. Australian Prescriber's December 2025 summary: when treatment is stopped, regaining weight is the norm. For orlistat, the 2007 meta-analysis found that in the four trials with a second year both groups regained at similar rates and the difference between them was preserved.