Contrave vs Saxenda in Australia

No randomised trial has compared naltrexone/bupropion (Contrave) with liraglutide 3 mg (Saxenda or its generics); searches of the trial literature return only placebo-controlled trials, observational studies and network meta-analyses. The table puts the two largest placebo-controlled trials side by side. They are separate experiments, run years apart in different populations, and a gap between the columns cannot be read as one medicine beating the other.

The two come from different drug families and their risks barely overlap. Contrave (naltrexone, an opioid blocker, with bupropion, the ingredient in Zyban) carries warnings about the brain, blood pressure and drug interactions. Liraglutide, a GLP-1 receptor agonist like Ozempic and Wegovy, carries warnings about the gut, pancreas, gallbladder and heart rate. Figures are from each medicine's Australian Product Information, not the American labels the earlier version of this page used; the Australian Contrave document has no boxed warning, the American one does.

Contrave lists thirteen contraindications: uncontrolled high blood pressure; any history of seizures; a central nervous system tumour; acute alcohol or benzodiazepine withdrawal; a history of bipolar disorder; other bupropion or naltrexone products; current or past bulimia or anorexia nervosa; opioid dependence, methadone or buprenorphine treatment, or acute opioid withdrawal; MAOIs within 14 days; pregnancy; severe liver disease; end-stage kidney failure; and allergy to either ingredient. Any opioid must have been stopped for 7 to 10 days before starting, and Contrave stopped 3 days before any planned opioid treatment such as surgery. Liraglutide has one contraindication: allergy to liraglutide or its excipients.

Both cause nausea, and for both it clusters in the first weeks. Pooled Contrave trials: nausea 31.8% against 6.7% on placebo, constipation 18.1%, vomiting 9.9%; most nausea began within four weeks and almost all had resolved by week 24. Pooled liraglutide trials: nausea 39.3% against 13.8%, diarrhoea 20.9%, constipation 19.4%, vomiting 15.7%, injection site reactions 9.0%, described as mild to moderate and transient. The difference is who keeps taking it: 23.8% stopped Contrave for an adverse event against 11.9% on placebo (most often for nausea, headache, dizziness and vomiting), compared with 9.8% against 4.3% for liraglutide.

Both are Schedule 4 prescription-only medicines with the same starting criteria in their Product Information: a BMI of 30 or more, or 27 to under 30 with at least one weight-related condition such as type 2 diabetes or prediabetes, high blood pressure, abnormal cholesterol or sleep apnoea, alongside a reduced-energy diet and more physical activity. Both registered indications include the 5% stopping rule (16 weeks for Contrave, 12 weeks on 3.0 mg for liraglutide).

Contrave's prescriber must have read iNova's physician educational material, must measure blood pressure and pulse before starting, and must reassess at 16 weeks and then yearly, including a cardiovascular risk assessment.

Liraglutide pens are kept at 2 to 8 degrees: Chemist Warehouse lists ARX-Liraglutide as "unavailable online" and Your Discount Chemist sells fridge items in store only. The generic brands carry the same registered indication, dose schedule and 12-week rule as Saxenda (checked against Healthdirect's entry for Liraglutide Sandoz), and Saxenda's Product Information (last revised 26 June 2026) remains the fullest Australian reference for liraglutide 3 mg.

Several telehealth services prescribe Contrave after an online assessment: Weight Loss GP (August 2026) quotes $230 to $260 a month, and an aggregator checked in April 2026 listed Qoctor at $280 plus a $59.99 consultation and My Weight Loss Clinic at $290 plus $49, against retail prices of $249.99 to $254.95 in the table. Compounded GLP-1 products, including liraglutide, have been illegal to make or supply in Australia since 1 October 2024.

No trial answers this directly. On the placebo-controlled trials and the 2016 network meta-analysis, liraglutide 3 mg produced somewhat more weight loss than naltrexone/bupropion (8.0% against 2.6% on placebo in SCALE; 5.4% against 1.3% in the Contrave Product Information's analysis of COR-I; 5.3 kg against 5.0 kg beyond placebo in Khera 2016, with overlapping intervals) and far fewer people stopped it for side effects (9.8% against 23.8% in each medicine's pooled trials). The 2026 BMJ analysis rated neither as convincingly better than lifestyle change alone at one year and both among the drugs most often stopped. Contrave is the only one taken by mouth, and a pack costs $41 more than a pack of generic liraglutide at Chemist Warehouse (28 days against 30).

The Australian Journal of General Practice (April 2025) separates them by patient. For people with type 2 diabetes, cardiovascular disease, obstructive sleep apnoea, knee osteoarthritis or fatty liver disease it puts incretin-based medicines (the GLP-1 class, including liraglutide) first. For people without cardiovascular disease or hypertension it calls naltrexone/bupropion a reasonable option if nothing else rules it out.

No Australian guideline covers moving from Contrave to liraglutide or back. Neither Product Information mentions the other medicine, no dose of one corresponds to a dose of the other, and neither gives a washout period. Without that guidance, a switch means starting the new medicine at its own starting dose (Contrave one tablet a day, liraglutide 0.6 mg) and going through its escalation and early side effects. The documented trigger for a change is the registered checkpoint; the Australian Journal of General Practice advises trying another agent when less than 5% has been lost after 12 weeks on a maximum dose. Anyone still holding Saxenda pens has the TGA's advice to discuss alternatives with their prescriber; Saxenda's indication, dose and stopping rule are identical to the generic pens'.

Taking the two together has not been studied. The Saxenda Product Information says liraglutide is not recommended with any other medicine intended for weight loss, prescription or otherwise, because efficacy and safety have not been established. The Contrave document is silent on other weight-loss medicines; its combination rules are the contraindications with other bupropion or naltrexone products, opioids and MAOIs. No randomised trial has tested naltrexone/bupropion with any GLP-1 medicine. The only published data is a retrospective study from one Canadian clinic (2024) of 415 patients on semaglutide or liraglutide, 23% of whom had naltrexone/bupropion added, with self-reported weights and no control arm. An Australian Prescriber author wrote in 2022 that the two classes "could be combined", in an opinion piece with declared advisory roles for both manufacturers and no trial cited. Reddit accounts are individual reports.