Weight loss injections in Australia: what is approved and how they work.

Weight loss injections are prescription medicines that act like hormones your gut releases after eating. They slow how fast the stomach empties and act on appetite centres in the brain, so most people feel full sooner and think about food less. They are injected under the skin once a week with a pre-filled pen.

The medicines in this group are called GLP-1 receptor agonists. GLP-1 (glucagon-like peptide-1) is one of those gut hormones. Mounjaro also acts on a second hormone, GIP, so it is called a dual GIP/GLP-1 agonist. More detail: how Mounjaro works.

Treatment starts at a low dose that steps up every four weeks or so. That slow start is there to limit stomach side effects. They are not insulin, stimulants or supplements, and they are used alongside a reduced-energy diet and more physical activity, not instead of them.

As of 9 November 2026, two injections are TGA-registered for weight management and supplied in Australia: Wegovy and Mounjaro. A third, Saxenda, is no longer supplied. Ozempic is often talked about, but in Australia it is approved only for type 2 diabetes.

Sources: Wegovy PI (revised 3 Nov 2026); Mounjaro PI (revised 2 Oct 2026); Ozempic CMI (Aug 2026); TGA shortage database (Saxenda). Several generic liraglutide pens are on the ARTG, but we could not confirm any is on sale, so they are not listed.

For each medicine in depth: Wegovy in Australia, Mounjaro in Australia and Ozempic in Australia.

Wegovy and Mounjaro are approved for adults with a BMI of 30 or more, or a BMI of 27 to under 30 with at least one weight-related health condition. BMI (body mass index) is your weight in kilograms divided by your height in metres squared. Both are meant to be used with a reduced-energy diet and more physical activity.

Examples of weight-related conditions listed in the Mounjaro Product Information include high blood pressure, high cholesterol, obstructive sleep apnoea, heart disease, prediabetes and type 2 diabetes.

Meeting these criteria does not mean a medicine is right for you. A prescriber weighs your history, other medicines and goals. Registration criteria are not a recommendation for any individual.

In the main trials, people on Wegovy 2.4 mg lost 14.9% of their body weight on average over 68 weeks, and people on Mounjaro lost 16% to 22.5% depending on dose over 72 weeks. Everyone in these trials also had diet and activity counselling, and results varied widely from person to person.

STEP 1, STEP UP and OASIS 4 figures are treatment-policy estimates (counting everyone, whether or not they stopped). SURMOUNT-1 figures are the efficacy estimates (as if everyone stayed on treatment). SURMOUNT-5 was open-label with no placebo. Sources: Wilding et al., NEJM 2021; Wharton et al., Lancet Diabetes Endocrinol 2025; Jastreboff et al., NEJM 2022; Aronne et al., NEJM 2025; Wegovy PI Table 16.

Weight loss is fastest in the first six months and usually levels off later. In STEP 1 the lowest weight was not reached until about week 60. For Mounjaro specifically, see Mounjaro results by dose and week.

The most common side effects are stomach-related: nausea, diarrhoea, vomiting and constipation. They are most likely while the dose is being increased and are usually mild to moderate. Across Wegovy’s weight-management trials, 38.3% of people had nausea compared with 14.0% on placebo.

For Mounjaro, the pooled trials in the Product Information found stomach-related side effects in 37.1% to 43.6% of people depending on dose, compared with 20.4% on placebo. Most were mild (74%) or moderate (23.3%).

Less common but serious risks listed in the Consumer Medicine Information include:

• inflamed pancreas (pancreatitis): severe stomach pain that may spread to the back and does not go away
• gallbladder problems, including gallstones
• severe allergic reactions
• sudden changes to eyesight
• dehydration from vomiting or diarrhoea, which can affect the kidneys

The CMIs tell people to call their doctor straight away or go to the Emergency Department for serious symptoms. Since June 2025, these medicines must also warn about inhaling stomach contents during general anaesthesia or deep sedation, so tell your anaesthetist you take one.

Each medicine in detail: Wegovy side effects · Mounjaro side effects · Ozempic side effects.

Yes. Wegovy and Mounjaro are Schedule 4 (prescription-only) medicines. A lawful supply needs a prescription from a prescriber who has assessed you, dispensed by a registered Australian pharmacy. Any website that sends prescription medicines without a prescription is breaking the law, according to healthdirect.

The Medical Board of Australia says prescribing without a real-time consultation (in person, by video or by phone) is “not good practice and is not supported by the Board”. That includes prescriptions based only on an online questionnaire. In September 2026 Ahpra said it was investigating high-volume, single-treatment prescribing models, naming GLP-1 weight-loss medicines.

Seen an injection sold online without a prescription? Read how to spot an illegal Mounjaro seller before you pay.

No. As of 9 November 2026, no injection is PBS-subsidised for weight management in Australia. People prescribed Wegovy or Mounjaro for weight pay the full private price, which varies by dose and by pharmacy.

• Wegovy: the PBAC recommended a narrow listing (heart disease with obesity) in November 2025, but it did not go ahead. A revised proposal went to the November 2026 meeting, with outcomes due around 18 December 2026. Is Wegovy on the PBS?
• Mounjaro: the PBAC recommended a type 2 diabetes listing in March 2026; Eli Lilly declined in April 2026 and the process has ceased. There is no weight-management listing. Is Mounjaro on the PBS?
• Ozempic: PBS-listed for type 2 diabetes only, under authority rules. Use for weight is off-label and on a private prescription.

Anything sold as a GLP-1 injection outside a prescription and a registered pharmacy is not an approved medicine. The TGA has found products sold online that contained the wrong medicine, too much of it, or none at all.

More: retatrutide in Australia and spotting an illegal seller.

Most people regain weight after stopping. One year after the STEP 1 trial ended, people had regained about two-thirds of the weight they lost on semaglutide: 11.6 of 17.3 percentage points, leaving them 5.6% below where they started.

In SURMOUNT-4, people who switched from Mounjaro to placebo regained 14.0% of their weight over a year, while those who stayed on it lost a further 5.5%. Decisions about how long to stay on treatment belong to you and your prescriber. Eating well when you reduce or stop.

Smaller meals still need to cover protein, fibre and fluids. A 2025 joint advisory from four US nutrition and obesity bodies suggests about 1.2 to 1.6 g of protein per kilogram of body weight a day during active weight loss, plus strength training at least three times a week.

Practical starting points: protein first on the plate, smaller portions eaten slowly, water through the day, and plain foods on hand for queasy days. Read protein on a GLP-1, the portion guide and foods for nausea. An Accredited Practising Dietitian can tailor this to you.