Tirzepatide is the active ingredient in Mounjaro. It is also marketed as Zepbound in some overseas markets. Compounded versions were previously available in some circumstances, but since October 2024 pharmacy compounding of GLP-1 receptor agonists is generally not permitted under the usual exemptions. If you have been prescribed tirzepatide as a subcutaneous injection (into the layer of fat just below the skin), this guide explains the supplies and handling steps that commonly apply. Follow your prescriber's instructions and the product information for your specific medicine.

This guide covers common injection supplies, insulin syringe technique for confirmed vial products, injection-site rotation, storage checks, and when to contact your prescriber.

Injection supplies laid out for a confirmed vial-and-syringe workflow
Common supplies shown for a confirmed vial-and-syringe workflow: insulin syringe, vial, alcohol wipe, and sharps disposal.
A disposable injectable medication pen with a single-use pen needle attached and the protective cap removed, lying horizontally on a clean background
A disposable injectable medication pen with a single-use pen needle attached and the protective cap removed, lying horizontally on a clean....

1. What Is Tirzepatide?

Tirzepatide is a dual GIP/GLP-1 receptor agonist. It works on two gut hormone pathways simultaneously, which distinguishes it from semaglutide (which targets only GLP-1). Your prescriber can explain why tirzepatide has been prescribed and what outcomes are being monitored.

In Australia, Mounjaro is a prescription-only medicine. Check the current TGA-approved Product Information and follow your prescriber's advice for approved indications and use.

Tirzepatide has specific contraindications and precautions. Tell your prescriber if you or a close family member has had medullary thyroid carcinoma, if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN2), or if you have had a serious allergic reaction to tirzepatide/Mounjaro or any ingredient. Also tell them about pancreatitis (inflammation of the pancreas), gallbladder, kidney, stomach-emptying or severe gastrointestinal problems, or if you are pregnant, planning pregnancy, or breastfeeding. Follow your prescriber's advice and the current Product Information supplied with your medicine.

Since October 2024, pharmacy compounding of GLP-1 receptor agonists (including tirzepatide and semaglutide) is generally not permitted under the usual Australian compounding exemptions. Use only the branded product format or a vial presentation confirmed by your prescriber or pharmacist under current TGA requirements.

2. Approved Device Format vs Confirmed Vial

Australian patients should use only the branded product format or a vial presentation confirmed by their prescriber or pharmacist. This guide does not apply to unlabelled, overseas, research-use, or privately compounded vials.

Approved pen or device format

The branded Mounjaro KwikPen is a pre-filled multidose pen. For pens that accept pen needles, use a new compatible pen needle for each injection and follow the manufacturer's instructions for dose selection, priming, storage, and disposal. No syringe drawing or measuring is required.

Vial use only when confirmed

Only use a tirzepatide vial if it has been supplied by a pharmacy under your prescriber's instructions. Follow the pharmacy label for whether it is single-use or multidose, its concentration, storage, and beyond-use date. You should only draw a vial dose with the syringe type and volume instructions provided by your prescriber or pharmacist. This is the focus of the technique section of this guide.

3. What You Need

  • Insulin syringe: Use only the syringe type and volume specified by your prescriber or pharmacist. On a U-100 insulin syringe, 1 unit mark = 0.01ml. These are volume markings only; calculate the volume from the labelled concentration and prescribed dose, and do not interpret syringe unit marks as medication units. For small prescribed volumes, a smaller-capacity insulin syringe may improve measurement precision. Use one new sterile syringe for one vial entry and one injection only. Do not use the same syringe barrel, fixed-needle or detachable-needle, across multiple vials or medicines.
  • Alcohol wipes: 70% isopropyl alcohol wipes. One for the vial stopper, one for the injection site.
  • Your tirzepatide: Stored in the refrigerator as directed by your prescriber or pharmacy.
  • Sharps container: For used syringe disposal. Available from us in several sizes. Some councils, pharmacies, or local sharps programs may also provide containers or disposal options; check your local rules. See our disposal guide.

If you are new to self-injection and your prescriber or pharmacist has confirmed a syringe-based vial workflow, a starter supply kit includes 10 insulin syringes and 20 alcohol wipes. Use it only when the 1mL syringes match your pharmacy instructions. You still need your prescribed medicine and a sharps container.

4. Step-by-Step Injection Guide

This covers the process for injecting from a vial using an insulin syringe.

Step 1: Prepare your workspace

Wash your hands thoroughly with soap and water. Set out your syringe, alcohol wipes, vial, and sharps container on a clean surface. Having everything within reach before you start makes the process smoother.

Step 2: Prepare the vial

Remove the vial from the refrigerator only for the time recommended by the pharmacy label. Wipe the rubber stopper with an alcohol wipe and let it air-dry completely before inserting the needle.

Step 3: Draw your dose

Pull the syringe plunger back to draw in air equal to your dose volume if your pharmacy instructions say to do this. Insert the needle through the rubber stopper, push the air in, then invert the vial and slowly draw your prescribed dose. Draw slowly to minimise bubbles. Do not draw from more than one vial or medicine with the same syringe barrel, whether it is fixed-needle or detachable-needle. Use one new sterile syringe for one vial entry and one injection. If large bubbles affect the measurement, follow your pharmacy instructions; do not push drawn medication back into a multidose vial after the syringe has been removed or sterility is uncertain. Re-check your dose volume and withdraw the needle from the vial.

Your pharmacy label or prescriber/pharmacist must provide the dose volume for your exact concentration. You can use our dose volume calculator only as a cross-check; if it differs from the label or instructions, do not inject and contact your pharmacist or prescriber.

If you are unfamiliar with reading syringe markings, see our How to Read an Insulin Syringe guide.

Step 4: Prepare the injection site

Choose your injection site (see next section). Wipe the area with a fresh alcohol wipe. Let it air-dry completely before injecting. Injecting through wet alcohol stings.

Step 5: Inject

Gently pinch a fold of skin at the injection site if you have been instructed to do so. Use the angle advised by your prescriber or pharmacist for your device, needle length, and body type. The goal is subcutaneous delivery, not intramuscular injection (into the muscle beneath the fat). For short 4-6mm needles, 90 degrees is commonly used when instructed; longer needles or lean users may be advised to pinch the skin and/or use 45 degrees. Push the plunger down slowly and steadily.

Step 6: Hold and withdraw

After the plunger reaches the bottom, hold the needle in place for the time in your instructions. Withdraw the needle smoothly at the same angle. Press clean gauze, cotton wool, or a clean tissue gently on the site if needed. Do not rub, and do not apply alcohol into the puncture.

Step 7: Dispose

Drop the used syringe directly into your sharps container. Do not recap the needle.

5. Best Injection Sites for Tirzepatide

Tirzepatide is a subcutaneous injection. The three recommended sites are:

Abdomen

The most popular site. Inject into the lower abdomen, at least 5cm (2 inches) from the navel in all directions. Avoid the waistline and any scarred areas. The abdomen typically has a consistent fat layer and is easy to reach.

Front of thigh

Use the thigh area shown in your product instructions or by your prescriber or pharmacist, avoiding areas close to the knee, groin, scars, bruises, or irritation.

Upper arm (back)

The fatty area on the back of the upper arm. This site is easier if someone else is administering the injection, as it can be difficult to reach on your own. It is a legitimate site but less commonly used for self-injection.

Rotate injection sites as instructed. You may use the same body area if approved by the product instructions, but choose a different exact spot each time. Rotate between left and right sides, and between product-approved body areas where applicable. Rotation helps reduce local irritation and tissue changes, and may support more predictable injections. For a deeper dive on rotation strategies, see our injection technique guide.

6. Storage and Handling

  • Branded Mounjaro: Follow the manufacturer's storage instructions supplied with the pen, including refrigerator, room-temperature, light-protection, and disposal rules.
  • Pharmacy-supplied vial: Follow the pharmacy label for temperature, light protection, beyond-use date, and whether the vial is single-use or multidose.
  • Preparation time: Keep the product out only for the time needed to prepare and inject, unless your product information says otherwise.
  • Check expiry: Follow the use-by date provided by your prescriber or pharmacy.
  • Inspect before use: Inspect the product exactly as the pharmacy label or product information directs. Do not use it if it differs from the stated appearance, contains unexpected particles or discolouration, the vial is damaged, or you are unsure.

7. Managing Common Side Effects

Gastrointestinal side effects are common and may improve over time, but persistent, worsening, or severe symptoms should be discussed with your prescriber:

Nausea

Nausea is a known possible side effect. Follow your prescriber's advice and the product information. Contact your prescriber if symptoms are persistent, severe, or affecting fluid or food intake.

Seek urgent medical care if you develop severe abdominal pain, especially if it radiates to your back, persistent vomiting, or inability to keep fluids down. These can indicate pancreatitis or another serious problem.

Reduced appetite

Reduced appetite can occur. Follow your prescriber's nutrition and monitoring advice, especially if appetite changes make it hard to eat or drink normally.

Injection site reactions

Mild redness, swelling, or itching at the injection site can occur. Rotating your injection site and letting alcohol fully dry may help reduce avoidable local irritation, although injection-site reactions can still occur.

Constipation or diarrhoea

Constipation or diarrhoea can occur. Follow your prescriber's advice and contact them if symptoms are persistent, severe, or you cannot maintain fluids.

Gallbladder problems

Gallbladder problems (including gallstones and inflammation) have been reported with GLP-1 receptor agonists. Contact your doctor if you develop upper right abdominal pain, yellowing of the skin or eyes, or fever.

Hypoglycaemia (low blood sugar)

Hypoglycaemia is more likely when tirzepatide is used with insulin or sulfonylureas. If you use glucose-lowering medicines, follow your prescriber's monitoring and dose-adjustment advice.

Important: If you experience severe abdominal pain, persistent vomiting, or signs of an allergic reaction (difficulty breathing, severe rash, swelling of the face or throat), seek immediate medical attention.

When to call your prescriber

Most injections go smoothly - a small drop of blood or a brief sting are normal. The list below covers things that aren't normal and warrant a phone call to your prescriber:

  • Redness, warmth, swelling, spreading tenderness, or pus at the injection site, especially if it worsens or does not settle
  • A stable, non-tender lump that persists beyond about a week, or any uncertain lump
  • A hot, painful, or growing lump, spreading redness or swelling, pus, fever, red streaking, severe pain, dizziness, or confusion - seek prompt medical advice or urgent care
  • Rash, hives, spreading or generalised itching, worsening injection-site reactions, or symptoms beyond the injection site
  • Signs of a severe allergic reaction - swelling of face or throat, difficulty breathing - call 000 immediately
  • You realise you injected from a vial that was stored outside the temperature or time limits in the product instructions, or had unexpected cloudiness, discoloration, particles, or damage

Frequently Asked Questions

What size needle for tirzepatide injection?

For some prescribed vial-method subcutaneous doses, the prescriber or pharmacist may specify a fixed-needle insulin syringe, commonly 29G-31G and around 6mm, if appropriate for the dose volume. Use one new sterile syringe for one vial entry and one injection only; do not use the same syringe barrel, fixed-needle or detachable-needle, across multiple vials or medicines. For pen devices, use only compatible pen needles or built-in device needles specified by the product instructions. See our Needle Gauge Guide for a full breakdown.

Can I use the same syringe as semaglutide?

If you are injecting from a prescribed vial, your prescriber or pharmacist may recommend the same type of insulin syringe used for some other confirmed vial products. Never reuse the same physical syringe between injections or medicines. The syringe must match the prescribed volume and instructions.

What day should I inject tirzepatide?

Follow the schedule on your prescription and product information. If you need to change your injection day, your prescriber can advise on how to adjust safely.

What happens if I miss a dose?

If you miss a dose, refer to the missed-dose instructions provided by your prescriber or on your product information leaflet - timing rules differ between products. Do not double up without explicit guidance.

Is tirzepatide the same as semaglutide?

No. While both are prescription medicines that act on GLP-1 pathways, tirzepatide is a dual-action GIP/GLP-1 agonist (it targets two pathways), whereas semaglutide targets only GLP-1. They have different dosing schedules, dose escalation protocols, and clinical profiles. Your doctor will determine which is appropriate for you.

Can I buy injection supplies without a prescription in Australia?

In general, syringes, needles, and alcohol wipes can be purchased without a prescription in Australia, though local rules, supplier policies, and disposal requirements may apply. The medicine itself requires a prescription.

Common vial-injection supplies: