How to Get 3.75mg Mounjaro: The Clinical Route Explained

Why 3.75mg exists and what NICE guidance says about Mounjaro titration

Tirzepatide's UK licence, approved by the MHRA and reviewed in NICE's technology appraisal TA1026, specifies a titration schedule that moves in 2.5mg steps every four weeks: 2.5mg, then 5mg, then 7.5mg, up to a maximum of 15mg. The 3.75mg figure sits between two of those steps. It is not an off-the-shelf pen strength; it is a split dose, where a prescriber instructs a patient to use half a 5mg pen per injection rather than the full cartridge.

That kind of dose adjustment happens for one clinical reason: to help someone who found 5mg too uncomfortable to tolerate full-strength while still needing to progress beyond 2.5mg. SURMOUNT-1, one of the pivotal trials underpinning the licence, tracked nearly 2,540 adults over 72 weeks; the graded dose schedule was central to managing tolerability alongside efficacy. The lesson from that data is that the step-up plan matters. Skipping, rushing or improvising it carries real risk.

What this means in practice: a prescriber, not you, decides whether 3.75mg is appropriate for your situation. If you are currently on 2.5mg and wondering whether to move up, the right conversation is with the clinician overseeing your treatment, not a search engine. Read about how the 3.75mg dose is drawn from a 2.5mg pen if your prescriber has recommended this approach. If your prescriber has instead pointed you toward a 5mg pen, our guide explains how the 3.75mg dose is measured from a 5mg pen and what that process involves.

The only legal route: a prescription following clinical assessment

Mounjaro is a Prescription-Only Medicine under the Human Medicines Regulations 2012. That means a pharmacist cannot hand it over, and a website cannot sell it, without a valid prescription issued after a genuine clinical assessment. There are no legal shortcuts here.

The safe route runs like this. You complete a structured consultation, medical history, current medications, BMI, relevant conditions. A GPhC-registered Independent Prescriber reviews your answers. If tirzepatide is clinically appropriate, a prescription is issued; if it is not, you are told why. For existing patients seeking a dose adjustment to something like 3.75mg, evidence of your current treatment and recent weight is reviewed before any change is made.

One thing worth doing before you commit to any online provider: look them up on the GPhC pharmacy register at pharmacyregulation.org/registers. It takes under a minute. You enter the pharmacy name or registration number and confirm they are genuinely registered. Our own GPhC premises registration is 9012878, verifiable directly at that address. If a site you are considering does not appear there, that is a firm reason to stop.

If you are not yet sure whether Mounjaro is the right option for your situation, our treatment page sets out what a free consultation covers and how the process starts.

Fake pens, unverified sellers, and why this matters at 3.75mg specifically

The MHRA has issued repeated public warnings about counterfeit weight-loss pens sold through social media and unregistered online sellers. In October 2025, enforcement teams raided the first illicit UK site producing fake tirzepatide pens; across 2025, around 20 million doses of illegally traded weight-loss medicines (roughly £45m in street value) were seized. Some counterfeit pens have contained insulin. The MHRA advises reporting any suspect seller via the Yellow Card scheme.

The 3.75mg dose is worth mentioning specifically because it requires the patient to measure and draw half a pen themselves. That makes the integrity of what is inside the pen more critical, not less. A fake or contaminated pen measured at full dose is dangerous. A fake pen measured at half dose in the hope of reaching 3.75mg is doubly unpredictable.

Red flags to know: any seller offering these medicines without requiring a prescription, social-media accounts with Mounjaro or Ozempic in the bio, prices dramatically below the market, and discount codes attached to what are supposed to be prescription medicines. Legitimate providers do not operate like that. Our guide to buying Mounjaro online safely covers what to look for in more detail.

Eligibility for Mounjaro and how the 3.75mg step fits into your treatment plan

The UK licence covers adults with a BMI of 30 or above, or 27 or above alongside a weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea, type 2 diabetes or prediabetes. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. Meeting the licence criteria does not guarantee a prescription, the prescriber weighs up your full medical picture, current medications, and any contraindications.

If you are already established on Mounjaro through another provider and want to transfer, a prescriber will ask for evidence of your current dose and recent progress. A move to an intermediate step like 3.75mg is a clinical judgement, not a standard feature of every treatment plan. Most patients move through the licensed steps without needing it.

For those who do need it, it should be the prescriber's suggestion, not something sourced independently. If you are ready to begin that conversation, our page for people who want to buy Mounjaro walks through exactly what to expect from the consultation and ordering process. Our broader guide on getting Mounjaro in the UK explains the access routes available, both NHS and private. If you are curious about whether NHS criteria apply to you, our NHS access page sets out the current phased rollout honestly. You can also browse our FAQs or get in touch if you have a specific question before starting.

At nume, every repeat order and every dose change goes back to a prescriber for review. No automatic renewals, no algorithm deciding your next dose. Meet our clinical team to understand who is overseeing your care. When you are ready to start, speak to our prescribers through a free consultation, no obligation, same day.