Taking Mounjaro: a step-by-step guide to what actually happens

Step 1: your consultation and first prescription

Before a single pen is dispensed, a prescriber has to decide that Mounjaro is appropriate for you. At nume, that means completing a free consultation online, your answers are read the same day by a real, GPhC-registered Independent Prescriber, not processed by software. They look at your BMI, your health history, any medicines you already take, and whether the licensed eligibility criteria are met: adults with a BMI of 30 or above, or 27 or above alongside at least one weight-related condition such as high blood pressure or high cholesterol. Lower thresholds apply for some ethnic backgrounds under UK guidance.

Once approved, your prescription is issued and your pen is dispatched the same day, order before 12pm Monday to Friday and it arrives with DPD the next working day, tracked, in plain packaging. Worth planning around public holidays, where the 12pm cut-off still applies but the delivery day shifts accordingly. If you want more detail on what the consultation covers, the Mounjaro overview page lays out the full picture.

Step 2: your first injection and the 2.5mg starter period

The first four weeks are spent on 2.5mg. That surprises some people who expect to feel dramatic effects straight away. The starter dose is not meant to produce significant weight loss, its job is to introduce tirzepatide to your system gradually, reducing the chance of nausea and other gastrointestinal upset. The NHS patient information for tirzepatide explains this clearly, and NHS tirzepatide guidance is worth reading before you begin.

You inject into the fat layer of your abdomen, outer thigh, or upper arm, rotating the site each week to avoid skin irritation. The KwikPen hides the needle, many people who are wary of injections find it far more manageable than they expected. Keep the pen in the fridge at 2–8°C between doses; for the exact window of time it can safely be kept at room temperature, always check the Patient Information Leaflet that comes in the box. A practical guide to injection technique is available on the tips for taking Mounjaro page.

Step 3: dose titration and finding your maintenance level

After your first four weeks, your prescriber will review your progress and, if appropriate, move you to the next dose. Mounjaro comes in six strengths: 2.5, 5, 7.5, 10, 12.5, and 15mg. Dose steps happen roughly every four weeks, guided by how well you are tolerating treatment and whether further adjustment is clinically justified. At nume, every dose increase requires a clinical review, not a click-through on an app.

Most people find nausea and other gut symptoms are most noticeable in the first week or two after each step up, then settle. Staying well hydrated and eating smaller, lighter meals tends to help. If you need to think through what happens if you miss a dose or need to pause treatment, the guide to taking a week off Mounjaro covers that in detail. For broader context on how tirzepatide works as a medicine, the tirzepatide treatment page goes deeper on the mechanism.

NICE's appraisal of tirzepatide (NICE TA1026) recommends reviewing whether to continue if less than 5% body weight has been lost after six months at the highest tolerated dose. Your prescriber will factor this in at your reviews.

Step 4: settling into a long-term routine

Once you are on a stable dose, taking Mounjaro becomes a weekly habit, same day, same rough time. Many people attach it to something already fixed in their week: a Sunday evening after dinner, or first thing on a Monday morning. The day itself does not have to be rigid, but consistency within a day or two helps maintain steady levels.

Side effects tend to be less prominent once you have been on the same dose for a few weeks. A question the prescribers at nume hear regularly is whether lifestyle changes still matter on Mounjaro. They do: tirzepatide is licensed alongside a reduced-calorie diet and increased physical activity, not instead of them. The support guide for people already on Mounjaro covers diet, activity, and managing the appetite changes that treatment brings. And if you are looking at the cost of continuing treatment over time, the Mounjaro pricing page explains what private treatment involves.

If anything unexpected happens (severe stomach pain, signs of an allergic reaction, or anything that concerns you) contact a healthcare professional promptly. Side effects can be reported to the MHRA using the Yellow Card scheme. And if you have questions specific to your situation, our team is reachable through the contact page seven days a week.