01Understand your treatment
The big picture.
Mounjaro is a prescription medicine that can support weight loss by helping you feel less hungry. It is used alongside changes to food and activity. This guide is for adults using it for weight management, and is a starting point for a conversation with your GP.
Sources102How it works
Small signals. A different appetite.
It acts on two hormone receptors, called GIP and GLP-1, involved in appetite and blood sugar control. Think of them as places where your body receives messages.
Sources17- 01
Appetite signals
You may feel satisfied sooner and less hungry between meals.
- 02
Stomach emptying
Food leaves the stomach more slowly, especially early in treatment.
- 03
Blood sugar
It helps the pancreas release insulin when blood sugar is raised.
03Your guide
What can I expect?
In a 72-week study, adults without diabetes lost about 15–21% of their starting weight on average, depending on the dose, compared with about 3% with placebo. Both groups received support with food and activity.
These are study averages, not a promise or a personal target. Your response, side effects and health goals matter more than reaching a particular dose.
04Your guide
Taking it week by week
Dose steps, once a week
Any increase is at least 4 weeks after the last one. Follow your own prescription; do not increase it yourself.
- 2.5 mgWeeks 1–4
- 5 mgFrom week 5
- 7.5 mgIf prescribed
- 10 mgIf prescribed
- 12.5 mgIf prescribed
- 15 mgMaximum
The usual starting dose is 2.5 mg once weekly for 4 weeks, then 5 mg weekly. Your prescriber may increase it further in 2.5 mg steps, with at least 4 weeks between increases, up to 15 mg weekly. Follow your own prescription; do not increase it yourself.
Ask your pharmacist to demonstrate your exact device. Follow the leaflet for injection technique and storage. This guide does not teach click-counting or partial doses.
05Your guide
If you miss a dose
Take the missed dose if there are at least 3 days until your next scheduled dose. If there are fewer than 3 days, skip it and take the next dose on your usual day. Never double up. Leave at least 72 hours between injections. If several doses are missed, ask your prescriber how to restart.
06Your guide
Side effects: what to expect
Side effects in numbers
What does “common” look like?
In two 72-week weight-management studies, people taking Mounjaro reported the following effects. These figures combine doses and include adults with and without type 2 diabetes. Everyone in the studies also received food and activity support.
Sources1These are people who reported an effect during treatment, not a risk with each injection. One person could report several effects. A report does not mean the medicine caused every case. “1 in” figures and the 100-person pictures are approximate; percentages show the published values. Your experience may differ.
Other effects worth knowing about
These were also reported in the same studies. Percentages combine the treatment doses.
- IndigestionDiscomfort after eating9.3%
- Tummy painAbdominal pain reporting term5.2%
- BurpingBelching4.9%
- Hair lossHair shedding4.7%
- DizzinessFeeling light-headed4.5%
About the studies & rates by dose
SURMOUNT-1 and SURMOUNT-2 were randomised trials funded by the manufacturer. SURMOUNT-1 enrolled adults with obesity, or overweight plus a weight-related condition, without diabetes. SURMOUNT-2 enrolled adults with overweight or obesity and type 2 diabetes. The 72 weeks included gradual dose increases. The figures come from Table 4 of the Australian product information (September 2026).
Mounjaro: 2,519 people.
| Effect | 5 mgn = 630 | 10 mgn = 948 | 15 mgn = 941 |
|---|---|---|---|
| Nausea | 24.6% | 29.0% | 28.0% |
| Diarrhoea | 18.7% | 20.8% | 22.5% |
| Constipation | 16.8% | 14.1% | 10.8% |
| Vomiting | 8.3% | 10.8% | 12.5% |
The 5 mg group comes only from SURMOUNT-1; the 10 mg and 15 mg columns combine both studies. Differences therefore reflect the populations as well as the doses. These are not figures for the 2.5 mg starting dose. Do not change your dose based on this table.
Sources1What can help?
Try smaller meals, stop eating when comfortably full, and avoid foods that make symptoms worse. Take regular sips of fluid. Ask your pharmacist about suitable treatment for constipation.
Digestive effects are often mild or moderate and can be more noticeable as the dose increases. Contact your GP if they persist, interfere with daily life, or affect eating or drinking. Discuss symptoms before your next dose increase; severe symptoms need assessment.
07Know when to get help
When to get help
Emergency · Call 000
Call 000 for trouble breathing, swelling of the tongue or throat, collapse, or immediate danger from thoughts of self-harm.
Urgent
Seek urgent medical care for severe, lasting tummy pain (sometimes spreading to the back), repeated vomiting with inability to keep fluids down, very little urine, or tummy pain with fever or yellow skin. Do not take another dose if pancreatitis is suspected until assessed.
Urgent
Severe bloating with vomiting and inability to pass stools or wind also needs urgent care.
Urgent
Sudden loss of vision needs urgent assessment. Contact your GP promptly about new or worsening depression or unusual changes in mood.
08Plan ahead
Important conversations
Tell your GP about all medicines and health conditions, especially previous pancreatitis, severe stomach-emptying problems, kidney problems or diabetic eye disease. Insulin and some diabetes tablets can increase the risk of low blood sugar; ask for a prevention and treatment plan.
Tell the anaesthetist or procedural team before surgery or sedation. They will give you an individual plan; do not decide yourself when to withhold treatment.
09Plan ahead
Pregnancy and contraception
Do not use Mounjaro during pregnancy. Discuss a planned pregnancy with your GP: treatment should stop at least one month beforehand. If you become pregnant, stop treatment and contact your prescriber. Discuss breastfeeding before use.
If you use the contraceptive pill, switch to a non-oral method or add condoms for 4 weeks after starting Mounjaro and for 4 weeks after every dose increase. Your GP or pharmacist can help you choose.
10Your guide
Think beyond the first few months
Weight management often needs ongoing support. In a withdrawal study, people who stopped tirzepatide tended to regain weight, while continued treatment helped maintain weight loss.
Plan regular reviews with your GP to discuss benefits, side effects, nutrition, activity, affordability and whether treatment still suits you. Make a plan together before stopping.