What is Mounjaro (tirzepatide)?

Mounjaro is the brand name used in Australia for tirzepatide, a prescription-only injectable medicine supplied by Eli Lilly Australia Pty Ltd. It belongs to a class of medicines that act on gut hormone receptors involved in blood glucose regulation and appetite signalling. This page sets out what Mounjaro is, what it is registered for in Australia, how the active ingredient works, who it is prescribed for under its registered indications, and the safety information patients and clinicians need to be aware of.

The information below is reproduced for general educational purposes from the Australian Register of Therapeutic Goods (ARTG), the TGA’s published consumer medicine information, and the Australian Public Assessment Report for Mounjaro. It is not an endorsement, a comparative claim, or a recommendation for any individual person.

What is Mounjaro?

Mounjaro is the brand name of a prescription medicine. The active ingredient is tirzepatide, a once-weekly injectable peptide.

In Australia, Mounjaro is supplied as a single-dose pre-filled pen (autoinjector) in several strengths. Different strengths exist because tirzepatide is typically introduced at a low starting dose and adjusted under clinical supervision. The product is administered as a subcutaneous injection, generally once weekly.

Mounjaro sits in Schedule 4 of the Australian Poisons Standard, meaning it is a prescription-only medicine. It can only be supplied lawfully in Australia on a valid prescription from an authorised prescriber.

What Mounjaro is registered for in Australia

The Therapeutic Goods Administration (TGA) includes prescription medicines on the Australian Register of Therapeutic Goods (ARTG) for specific, defined uses. These are known as the medicine’s registered indications and are set out in the approved Product Information.

Reproducing the registered indication verbatim, without paraphrasing, embellishing or summarising into marketing language, is the standard approach for general information about a registered medicine. The full text below is taken from the current TGA record for Mounjaro and is included here for neutral product identification and information.

Other Mounjaro ARTG entries exist for additional pen strengths and for vial presentations supplied through specific channels. The pre-filled pen entries above are the primary commercial entries available in Australia at the time of writing. The full list can be searched on the public ARTG at tga.gov.au.

Whether Mounjaro is clinically appropriate for any individual person is a separate question, one that depends on their full medical history, current medications, and a clinical assessment by an authorised prescriber.

How tirzepatide works

Tirzepatide works on two natural hormone systems in the body, called GLP-1 and GIP. These hormones are normally released after eating and help the body manage blood sugar and feelings of fullness.

By acting on both systems at once, tirzepatide can:

• help the pancreas release insulin when blood sugar is high
• slow down how quickly the stomach empties
• reduce appetite signals in parts of the brain that control hunger

This combined action is what makes tirzepatide different from medicines that only work on one of these systems. Tirzepatide is given as a once-weekly injection under the skin.

Who Mounjaro is prescribed for

Mounjaro is prescribed in Australia within the scope of its registered indications, set out verbatim above. In practical terms, this means it is considered by prescribers for two distinct clinical situations.

For type 2 diabetes, the registered indication covers adults whose type 2 diabetes is insufficiently controlled, used alongside diet and exercise, either on its own when metformin is not tolerated or is contraindicated, or in combination with other type 2 diabetes medicines.

For chronic weight management, the registered indication covers adults with a BMI of 30 kg/m² or higher, or adults with a BMI of 27 to under 30 kg/m² in the presence of at least one weight-related comorbid condition (such as hypertension, dyslipidaemia, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes). In this context it is registered as an adjunct to a reduced-calorie diet and increased physical activity, that is, alongside ongoing lifestyle measures, not in place of them.

In both indications, whether the medicine is appropriate is a clinical judgement made by an authorised Australian prescriber, taking into account the individual’s full history, contraindications, other medications, and ongoing monitoring.

Important safety information

Mounjaro is a prescription medicine. Like any prescription medicine, it has known side effects, contraindications, and situations in which extra care is needed. The information below is summarised from the TGA-published Product Information and the Australian Public Assessment Report. It is not exhaustive and does not replace advice from an Australian health professional.

Common side effects

The most frequently reported adverse effects of tirzepatide are gastrointestinal. These include:

• Nausea
• Diarrhoea
• Vomiting
• Constipation
• Decreased appetite
• Dyspepsia (indigestion) and abdominal discomfort

These effects are most common when treatment starts or when the dose is increased, and typically reduce in frequency and intensity over time. They are part of how dose adjustment is managed under clinical supervision.

Serious adverse effects and warnings

The TGA-published Product Information identifies a number of serious risks that prescribers and patients are expected to be aware of. These include, but are not limited to:

• Acute pancreatitis. Persistent, severe abdominal pain should be evaluated promptly.
• Severe gastrointestinal disease. Tirzepatide has not been studied in patients with severe gastrointestinal disease, including severe gastroparesis, and is not recommended in these patients.
• Acute kidney injury. Dehydration related to severe gastrointestinal side effects has been associated with worsening renal function in some patients.
• Hypoglycaemia. The risk of low blood sugar is meaningfully increased when tirzepatide is used together with insulin or sulfonylureas; dose adjustment of the concomitant medication may be required.
• Hypersensitivity and allergic reactions. Including, rarely, severe reactions such as anaphylaxis or angioedema.
• Acute gallbladder disease. Including gallstones and cholecystitis, has been reported with GLP-1 receptor agonists.
• Diabetic retinopathy complications. In people with pre-existing diabetic retinopathy, rapid improvement in glucose control has been associated with temporary worsening of retinopathy, and ongoing eye monitoring is recommended.
• Pulmonary aspiration during anaesthesia. Because GLP-1-class medicines slow gastric emptying, anaesthetists may need to be informed before any planned surgery or procedure involving sedation.
• Thyroid C-cell tumours. Tirzepatide has caused thyroid C-cell tumours in rodent studies. The relevance to humans has not been determined. It is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or in patients with Multiple Endocrine Neoplasia syndrome type 2.

This is a high-level summary. The full Consumer Medicines Information (CMI) and Product Information (PI) registered with the TGA list the complete set of precautions, contraindications, drug interactions and reporting requirements, and should be read in full alongside advice from a qualified prescriber.

Pregnancy, breastfeeding and fertility

Mounjaro is generally not recommended during pregnancy, and the TGA-published Product Information sets out specific guidance on contraception, planning for pregnancy, and breastfeeding. Anyone in this stage of life who is considering, taking or stopping a tirzepatide-containing medicine should discuss the implications with a qualified prescriber.

How Mounjaro is prescribed and supplied in Australia

Because Mounjaro is a Schedule 4 prescription-only medicine, the pathway to use it in Australia involves several steps that exist to protect patient safety and ensure ongoing oversight.

Clinical assessment. A qualified prescriber, typically a health practitioner or specialist, assesses whether the medicine is clinically appropriate, based on the patient’s history, current medications, contraindications and the registered indications.

Prescription. If clinically appropriate, the prescriber issues a valid Australian prescription. The prescription specifies the product, the strength, the dose schedule and the supervision arrangements.

Dispensing. The medicine is dispensed by a registered Australian pharmacy on receipt of the valid prescription. Pharmacists provide counselling on how to use the medicine, what to watch for, and how to manage side effects.

Ongoing review. Tirzepatide therapy is monitored over time, with regular reviews to check tolerability, response, side effects, and whether continued treatment remains appropriate. Dose adjustments and changes happen under the prescriber’s supervision.

About ARTG inclusion

ARTG inclusion is the legal mechanism by which a therapeutic product can be supplied in Australia. Inclusion follows TGA evaluation of safety, quality and efficacy data for the specific, defined uses set out in the Product Information.

For a deeper explainer of how ARTG inclusion works, what AUST R and AUST L numbers mean, and what inclusion does, and does not, guarantee for any individual person, see the related explainer below.