What Is 3.75mg Mounjaro and Where Does It Sit in Treatment?

Step 1, understanding what the licensed doses actually are

When Eli Lilly's Mounjaro was approved by the MHRA for weight management in the UK, the licence set out exactly six doses: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg. Each strength comes in its own KwikPen, pre-filled with four weekly doses. The full picture on Mounjaro covers the mechanism and clinical background, but the short version is this: 3.75mg sits between two of those licensed rungs and does not correspond to any approved product. There is no 3.75mg pen, no 3.75mg cartridge and no instruction in the Mounjaro SmPC for a prescriber to target that figure.

The confusion usually comes from one of two places. Some people assume you can inject half of a 7.5mg pen's dose. Others have encountered the figure in online communities where dose-splitting is discussed informally, and our 3.75mg Mounjaro page goes into detail about why neither of those sources carries any clinical authority. The SmPC is the document that governs how the medicine is used legally in the UK, and it does not describe 3.75mg as a dose.

If you are reading the 1.25mg Mounjaro page alongside this one, you will notice a similar pattern: non-licensed dose figures circulate widely online, often because patients are trying to manage side effects by reducing the amount they inject. That instinct is understandable, but adjusting doses outside the licensed schedule without prescriber involvement creates real clinical risk.

Step 2, how the licensed titration actually works

The starting dose of Mounjaro is 2.5mg once weekly for four weeks. This is a tolerability period, not a therapeutic target: its job is to let your digestive system adapt to the medicine before the dose climbs. After that first month, a prescriber reviews your response and, if things are going well, moves you to 5mg. From 5mg onward, increases typically happen in four-week steps through 7.5mg, 10mg, 12.5mg and finally 15mg. Not everyone reaches 15mg, and the prescriber's goal is the lowest dose that delivers meaningful benefit with acceptable side effects.

The tirzepatide dosing page explores the schedule in more detail, but the key clinical principle is that each increase is a deliberate, supervised decision. Prescribers look at weight loss to date, any side effects you have reported, and whether the current dose is still doing useful work. That review is what makes titration safe. Attempting to create an intermediate dose (for example by splitting a pen) removes that review entirely and introduces injection errors that can affect how much medicine actually reaches your tissue.

NICE's appraisal of tirzepatide, TA1026, focuses on clinical outcomes at the licensed doses studied in the SURMOUNT programme. Intermediate figures like 3.75mg have no evidence base in that body of research.

Step 3, what to do if you want to slow down between doses

The genuine question behind most searches for 3.75mg Mounjaro is: can I reduce my dose if I'm struggling with side effects? The honest answer is that the licensed route does allow you to stay at a lower dose for longer, or to discuss with your prescriber whether your current dose is right for you. What it does not support is splitting a pen to create an unlicensed strength.

Nausea, loose stools, reduced appetite and fatigue are the most commonly reported effects, particularly after starting or after a dose increase. For most people they settle within a week or two. The NHS tirzepatide medicines page lists the full side-effect profile and explains which symptoms warrant urgent attention. If you are finding the current dose hard to manage, the right step is to contact your prescriber and have that conversation, not to try to engineer a smaller injection.

Anyone considering treatment for the first time will find the treatment overview a useful starting point. For existing patients wondering whether they are on the right dose for their situation, the prescriber relationship is the appropriate place to work that out, and nume aftercare exists precisely for those questions between appointments.

If you're thinking about cost alongside all of this, the Mounjaro cost and access page covers what private treatment typically involves and what to look for in a legitimate provider.

Step 4, clinical assessment before any Mounjaro prescription

Mounjaro is a prescription-only medicine, which means a prescriber must assess your suitability before treatment starts and before any dose change. That is not a formality. The prescriber is checking for conditions that affect safety, medicines that may interact, and whether the BMI and health criteria in the licence are met.

At nume, a GPhC-registered Independent Prescriber reads every consultation personally, not software, not an automated decision tree. The clinical team page explains the people behind that review. Eligibility for Mounjaro as a private patient requires a BMI of 30 or above, or a BMI of 27 or above alongside a weight-related health condition such as high blood pressure, high cholesterol or type 2 diabetes. Lower thresholds apply for some ethnic backgrounds under UK guidance. BMI alone does not guarantee a prescription; the full clinical picture matters.

If you are curious about what treatment through a regulated service involves more broadly, the weight-loss treatment page gives an honest account. And if you have specific questions before committing to anything, the FAQs cover the most common ones, or you can reach the team directly via the contact page. When you are ready to take the next step, the free consultation is the place to start.