Switching from Wegovy to Mounjaro: prepare your care plan

Why discuss a switch from Wegovy to Mounjaro?

You might want a review because side effects are difficult, your progress has changed, medicine access is uncertain or the cost is hard to sustain. Start with the problem you want to solve. A change of medicine is one possible outcome, but it is not automatically the best answer for every concern.

Bring your longer-term progress and what you have tried, including the doses you actually used and any interruptions. The clinician can consider whether the current treatment has had an appropriate trial, whether nutrition or other health needs require attention and whether a different medicine is suitable.

If you are still choosing an initial treatment, our Wegovy vs Mounjaro comparison covers that earlier decision. This guide is for preparing a transition discussion when you are already using Wegovy.

The doses are not interchangeable

Wegovy contains semaglutide and acts on GLP-1 receptors. Mounjaro contains tirzepatide and acts on both GIP and GLP-1 receptors. A number on one pen cannot be matched with a number on the other pen to choose your next dose.

The labelled Mounjaro starting regimen is 2.5 mg weekly for four weeks, followed by 5 mg. That information does not tell you when to start after your last Wegovy dose or whether switching is appropriate for you. Your prescriber needs to make those decisions, considering your previous treatment, tolerability and any time off medication.

Do not use both weekly treatments together or use leftover pens to create your own transition. The New Zealand Wegovy information advises against combining it with another GLP-1 receptor agonist. Our Mounjaro dosage guide explains the new medicine’s stages once a prescription has been agreed.

Agree the last dose and first dose in writing

A transition plan should name the date and strength of your final Wegovy injection, the prescribed starting Mounjaro strength and its first injection date. Ask the clinician to write the plan clearly enough that you and your dispensing pharmacist can check the same instructions.

Your prescriber sets the interval between medicines for your situation. Recent side effects, a treatment break, other medicines and your clinical situation can affect the plan. If you cannot remember your last injection date, say so before taking the next medicine.

What to bring to your switching appointment

• A photo or record of your current prescription and Wegovy pen strength.
• The date of your last injection, time at the current strength and any missed doses.
• Your reason for wanting to change, in your own words.
• A weight trend and notes on appetite, meals and daily activities.
• Side effects, their severity and whether you can eat and drink normally.
• A complete medicine list, including diabetes treatment and contraception.
• Pregnancy plans, upcoming surgery or other changes in your health.
• Your budget and any expected interruption to pharmacy supply.

For example, “I have been at this prescribed strength for six weeks and nausea is affecting breakfast and work” gives your clinician a concrete problem to assess. It is more useful than choosing a different pen solely because someone else lost more weight on it.

Our progress review guide helps you prepare the wider picture. Your usual GP should also know about treatment changes; see our guide to coordinating care.

What may change after the switch

Your appetite and stomach symptoms may change with a new medicine. Previous experience with Wegovy does not guarantee that you will tolerate Mounjaro in the same way. Follow the prescribed starting plan and discuss symptoms before any increase.

Read the Mounjaro side effects guide before starting so you know which symptoms need urgent help. Ask the pharmacist to demonstrate the KwikPen, confirm compatible needles and explain storage. The New Zealand Mounjaro KwikPen and Wegovy FlexTouch have different operating instructions.

If you use an oral contraceptive pill, Mounjaro needs an additional discussion: the advice is a non-oral method or an added barrier method for four weeks after starting and four weeks after each dose increase. Our contraception guide explains the questions to ask.

Arrange the next review before you need another pen. Keep the new routine simple: the injection day, prescribed dose, symptoms and doses remaining. Avoid judging the change on a single week of weight measurements.

Costs, pharmacy supply and follow-up

Confirm the medicine price and supply with the dispensing pharmacy before committing to a plan. Consultation fees and medicine costs are separate. At Stela, an initial doctor consultation is $300 and a doctor follow-up is $150; the appropriate booking depends on whether you are a new or existing patient.

Ask what happens if supply is delayed, whether a prescription needs to be changed and when the next review is due. Do not substitute an available pen strength yourself. Read our treatment budget guide for the other costs to consider.

Keep old and new medicines clearly separated while the plan is being organised. Once your clinician confirms you no longer need a medicine, ask the pharmacy about safe disposal. Do not pass unused prescription pens to someone else.

Your questions