Tirzepatide (Mounjaro) — NZ Medication Guide | KiwiMeds

ByRamon Wong, BPharm

✅ Reviewed by Ramon Wong, BPharm, Registered Pharmacist (New Zealand) | May 2026 — This information is for educational purposes only and is not a substitute for personalised advice from your doctor or pharmacist. Always seek professional guidance before making changes to your medications.

Tirzepatide (brand name: Mounjaro) is a medication used to treat type 2 diabetes and, in higher doses, obesity. It works as a dual GIP and GLP-1 receptor agonist — a unique mechanism that makes it more effective than older GLP-1 medications like semaglutide for many people. Mounjaro received Medsafe approval in New Zealand in December 2025 and is available on private prescription.

⚠️ Pharmac funding status: As of May 2026, tirzepatide (Mounjaro) is not funded by Pharmac. It is available in New Zealand on private prescription only and patients must pay the full cost out-of-pocket. Check the Pharmac Schedule for any updates.

What is tirzepatide used for?

In New Zealand, tirzepatide is prescribed for:

  • Type 2 diabetes — to improve blood sugar (glucose) control in adults
  • Weight management (obesity) — at higher doses, as an adjunct to diet and exercise in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition

Tirzepatide is not approved for type 1 diabetes and is not a substitute for insulin in people who need it.

How does tirzepatide work?

Tirzepatide is unique because it targets two gut hormone receptors simultaneously:

  • GLP-1 (glucagon-like peptide-1) — stimulates insulin release, reduces glucagon, slows gastric emptying, and suppresses appetite
  • GIP (glucose-dependent insulinotropic polypeptide) — enhances insulin secretion and may improve fat metabolism

This dual action is why tirzepatide produces greater reductions in blood sugar and body weight compared to GLP-1 medicines alone (such as semaglutide/Ozempic).

Mounjaro dose and how to take it

Tirzepatide is given as a subcutaneous injection (under the skin) once weekly. Available doses in New Zealand include 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg weekly pens.

  • Starting dose: 2.5 mg once weekly for 4 weeks
  • Titration: Dose increased by 2.5 mg every 4 weeks as tolerated
  • Maintenance dose: Usually 5–15 mg weekly depending on response and tolerability
  • Injection sites: Abdomen, thigh, or upper arm — rotate sites each week
  • Can be taken with or without food, and at any time of day

How effective is tirzepatide?

Clinical trial data from the SURPASS program (type 2 diabetes) and SURMOUNT program (obesity) show tirzepatide to be highly effective:

  • Blood sugar reduction (HbA1c): Reductions of 1.8–2.4% at the highest doses — significantly better than many other diabetes medications
  • Weight loss: Average weight loss of 15–22.5% body weight in obesity trials — among the highest figures seen in any pharmacotherapy to date
  • Many people with type 2 diabetes also achieve normal blood sugar levels (remission) on tirzepatide

Common side effects of tirzepatide

The most common side effects are gastrointestinal and usually improve over the first few weeks:

  • Nausea (very common, especially when starting or increasing dose)
  • Vomiting
  • Diarrhoea or constipation
  • Decreased appetite
  • Abdominal pain or discomfort
  • Injection site reactions (redness, bruising, itching)

To reduce nausea: start at the lowest dose, eat smaller meals, avoid high-fat or spicy foods, and take the injection at bedtime if helpful.

Serious side effects and warnings

While rare, the following require urgent medical attention:

  • Pancreatitis — severe persistent abdominal pain; stop tirzepatide and seek immediate medical care
  • Thyroid tumours — tirzepatide carries a warning (based on animal studies) about the risk of thyroid C-cell tumours; avoid if you have a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2)
  • Hypoglycaemia (low blood sugar) — especially if combined with insulin or sulfonylureas; dose reduction of the other agent may be needed
  • Kidney problems — severe dehydration from vomiting/diarrhoea can worsen kidney function; stay well hydrated
  • Diabetic retinopathy — rapid improvement in blood sugar can temporarily worsen retinopathy in people with existing eye complications

Who should not take tirzepatide?

Tirzepatide is contraindicated in people who have:

  • Personal or family history of medullary thyroid carcinoma (MTC)
  • Multiple Endocrine Neoplasia syndrome type 2 (MEN2)
  • Allergy to tirzepatide or any ingredients in Mounjaro
  • Type 1 diabetes or diabetic ketoacidosis (DKA)

Tirzepatide should be used with caution in people with a history of pancreatitis, severe gastrointestinal disease, kidney impairment, or existing diabetic eye disease.

Tirzepatide and pregnancy / breastfeeding

Tirzepatide is not recommended during pregnancy. Animal studies have shown potential harm to the developing foetus. Women who could become pregnant should use effective contraception while taking this medicine. Discontinue tirzepatide at least 2 months before planning a pregnancy.

It is unknown whether tirzepatide passes into breast milk. Breastfeeding is generally not recommended while taking tirzepatide — discuss with your doctor.

Tirzepatide interactions with other medicines

Important interactions to be aware of:

  • Insulin and sulfonylureas (e.g., glipizide, glibenclamide) — increased risk of hypoglycaemia; dose reduction of the insulin or sulfonylurea is usually required
  • Oral medications — because tirzepatide slows gastric emptying, it may affect the absorption and timing of other oral medicines; discuss with your pharmacist
  • Oral contraceptives — consider using a non-oral contraceptive method for 4 weeks when starting tirzepatide or during dose increases, as the pill’s absorption may be temporarily affected

Tirzepatide vs Ozempic (semaglutide) — what’s the difference?

Both are injectable weekly medications used for type 2 diabetes and weight loss, but they work differently:

  • Semaglutide (Ozempic/Wegovy) — GLP-1 agonist only; Ozempic is funded by Pharmac for type 2 diabetes in NZ
  • Tirzepatide (Mounjaro) — dual GIP + GLP-1 agonist; produces greater average weight loss and HbA1c reduction in head-to-head trials; not currently funded in NZ
  • In the SURMOUNT-5 trial comparing the two directly, tirzepatide produced approximately 20% body weight loss versus 14% with semaglutide

Cost of Mounjaro in New Zealand

Since Mounjaro is not funded by Pharmac, patients pay the full private price. As of 2025, typical private costs in NZ range from approximately $350–$600 per month depending on the dose and pharmacy. Some private health insurance plans may cover part of this cost — check with your insurer.

To get a prescription, you will need to see a GP or specialist who can assess whether Mounjaro is appropriate for you based on your diabetes control, weight, and overall health.

Frequently asked questions about tirzepatide in NZ

Is Mounjaro available in New Zealand?
Yes. Mounjaro (tirzepatide) received Medsafe consent in December 2025 and is available in NZ on private prescription.

Is Mounjaro funded by Pharmac?
No. As of May 2026, tirzepatide is not on the Pharmac schedule and must be paid for privately.

Is tirzepatide better than Ozempic?
Clinical trials show tirzepatide produces greater average weight loss and blood sugar reduction than semaglutide. However, individual responses vary and Ozempic may be a more practical choice for many NZ patients as it is funded by Pharmac.

Do I need a specialist referral for Mounjaro?
No — your GP can prescribe Mounjaro if they feel it is appropriate. However, some GPs may refer you to an endocrinologist or diabetes specialist for assessment.

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