By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv
Mounjaro dosage: why you start low and go up slowly
Mounjaro dosage is set gradually, step by step, not all at once. You start with a low dose of 2.5 mg once a week and go up slowly, according to your response and how well you tolerate it. This way, the body gets used to the drug, and digestive side effects usually stay mild. In this article, I bring together the dose steps, what to expect at each step and what to do if you miss an injection. If you are just about to begin, my practical guide to starting Mounjaro and your weekly routine covers the first weeks in more detail.
What is Mounjaro and how does it work?
Mounjaro is a weekly injection whose active ingredient is tirzepatide. The drug activates two natural gut hormones: GLP-1 and GIP. Both hormones increase the feeling of fullness and slow stomach emptying. In addition, they improve blood sugar control. That is why the drug is used both to treat obesity and to treat type 2 diabetes. You will find a broad overview of the drug in my complete guide to Mounjaro.
The injection goes under the skin on the same day each week. You can inject into the abdomen, the thigh or the upper arm, and it is a good idea to change the injection site from time to time. Before you start, check with your doctor whether Mounjaro treatment suits you.
Mounjaro dosage steps, week by week
According to the European Medicines Agency’s product information, the starting dose is 2.5 mg once a week. After four weeks, you go up to 5 mg. From there, if needed, you can increase in steps of 2.5 mg. However, you stay on each dose for at least four weeks before the next step.
- 2.5 mg: a starting dose only, for four weeks. Its goal is to let the body adjust, not to bring about a large weight loss.
- 5 mg: the first treatment dose. Some patients stay on it long term.
- 7.5 mg: an in-between step, for at least four weeks.
- 10 mg: another treatment dose that suits many patients.
- 12.5 mg: an in-between step before the maximum dose.
- 15 mg: the maximum dose, once a week.
In other words, the recommended maintenance doses are 5, 10 or 15 mg. At the fastest pace, you reach 15 mg after twenty weeks. But you do not have to get there. If your weight is coming down nicely and the side effects are tolerable, you stay on your current dose.
What to expect at each Mounjaro dosage step
In the first weeks, many people notice a lower appetite and feel full quickly. At the same time, nausea, diarrhea, vomiting or constipation may appear. According to the European label, these effects are common mainly while the dose is going up, and they ease over time. Most were mild or moderate.
So each dose increase may bring back mild nausea for a few days. This is expected and usually passes. On the other hand, repeated vomiting, severe abdominal pain or signs of dehydration call for a visit to the doctor. Severe pain in the upper abdomen that spreads to the back may point to inflammation of the pancreas. In that case, stop the injections and get checked right away. You will find more on this topic in my article on coping with Mounjaro side effects.
How much weight you lose at each Mounjaro dosage
The SURMOUNT-1 trial included 2,539 adults with obesity and without diabetes. Participants increased the dose gradually over twenty weeks and continued treatment until week 72. At the end of the study, the average weight loss was 15.0% on 5 mg, 19.5% on 10 mg and 20.9% on 15 mg. By contrast, the placebo group lost only 3.1%.
Mounjaro dosage: missing an injection or changing the day
Forgot to inject? If up to four days have passed since your usual day, inject right away. If more than four days have passed, skip that dose and continue on your usual day. In any case, never inject two doses to “make up” for a missed one.
Foundayo is a daily pill, so its schedule works differently. I explain how the Foundayo dose is increased separately.
In addition, you can move your injection day to another day of the week. The condition is that at least three days pass between two injections. After a long break of several weeks, talk to your doctor before going back to your previous dose. Sometimes the doctor will recommend going back to a lower dose to reduce nausea.
Types of pens: what you need to know
The European label describes three forms of Mounjaro: a multi-dose pen (KwikPen), a single-dose pen and a vial. The KwikPen holds four fixed weekly doses of the same strength. So when you go up a dose, you need a prescription for a new pen in the right strength. Do not change the amount of the dose in the pen on your own. Your pharmacist will show you how to use and store the pen you received.
The pill, pregnancy and breastfeeding
Mounjaro slows stomach emptying, so it may weaken the absorption of the birth control pill. Accordingly, Lilly’s US guidance recommends that women who take the pill switch to a non-oral method. Alternatively, they can add a barrier method such as a condom. The recommendation applies for the four weeks after starting treatment, and also for the four weeks after each dose increase. The European label, by contrast, states that the effect is not clinically significant. I recommend caution, especially during periods of dose increases.
The drug must not be used during pregnancy. The European label recommends stopping Mounjaro at least one month before a planned pregnancy, because of its long duration of action. You will find more details in my article on stopping a weight loss drug ahead of pregnancy.
Before surgery or anesthesia
Because the stomach empties slowly, tell the anesthesiologist about your treatment before any general anesthesia or sedation. This way, the team can prepare in advance and reduce the risk of food from the stomach reaching the lungs.
Mounjaro dosage alongside nutrition and activity
The drug lowers appetite, but the quality of your food still matters. First, make sure you eat protein at every meal and drink enough fluids. Second, small, slow meals reduce nausea, especially after a dose increase. In addition, strength training helps prevent muscle loss as you lose weight.
A dietitian works in our clinic. In addition, when needed, I refer patients to a multidisciplinary body-and-mind team: dietitians, psychologists, holistic coaches, naturopaths and complementary medicine practitioners, as well as Pilates and yoga instructors and experts in stress-reduction techniques.
The bottom line
Mounjaro dosage goes up slowly: you start at 2.5 mg, go up to 5 mg after four weeks, and continue in steps of 2.5 mg as needed, up to 15 mg at most. The slow pace reduces side effects, and not everyone needs the maximum dose. The right dose is the one that brings a good result with tolerable side effects. It is best to decide on it together with a doctor who knows you.
The information in this article is general information and does not replace personal medical advice.
Questions and answers
What is the starting dose of Mounjaro?
You start at 2.5 mg once a week for four weeks. After that, you go up to 5 mg.
Do I have to reach 15 mg?
No. The maintenance doses are 5, 10 or 15 mg. You go up only if needed, and only if your body responds well.
Where do I buy Mounjaro in Israel, and how much does it cost?
You can buy the drug only with a prescription. All four of Israel’s health funds (HMOs) provide Wegovy and Mounjaro through their supplementary insurance plans, at a discount of about 50%. The prices are published on the health funds’ websites. You will find more details in my article on Mounjaro in Israel’s health funds.
What happens when you stop treatment?
For many people, appetite returns, and some of the weight comes back. That is why it is wise to plan the stop in advance, with stable eating and exercise habits.
Sources
Mounjaro: EPAR – Product Information (Summary of Product Characteristics)
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