Mounjaro®
Starting from £179.99/mo
Start journey Learn moreHow to work out whether stepping up to 5mg is right for you
What 5mg of Mounjaro actually does compared with the starter dose
People often ask what 5mg Mounjaro does that 2.5mg doesn't. The honest answer: it does more of the same thing, a bit more firmly. Tirzepatide is a dual GIP and GLP-1 receptor agonist, which means it acts on two gut-hormone pathways involved in appetite and blood sugar. It slows how quickly your stomach empties and dials up the feeling of fullness, so meals satisfy you sooner and cravings ease off between them.
The starter dose has a specific job. The 2.5mg pen exists to let your system adjust gently, keeping early nausea to a minimum, rather than to drive weight loss on its own. The 5mg dose is where the effect starts to build in earnest, though it still sits at the lower end of the licensed range that runs up to 15mg. The NHS describes tirzepatide's action and what to expect from it in plain terms on its patient guide to tirzepatide.
What you feel at 5mg varies. Some people notice appetite drops off further; others find it much like the starter dose but steadier. Neither is a sign it's working better or worse. Weight change is gradual and shaped by your food, movement and biology as much as the milligram number. If you want the full arc of the dose ladder in context, our Mounjaro dosage chart lays out each step and what it's for.
Worth remembering: a higher number isn't inherently better. The right dose is the lowest one that gives you a useful response without side effects you can't live with.
When most people move from 2.5mg to 5mg, and why it isn't a fixed date
The licensed schedule starts at 2.5mg and increases in roughly four-week steps, with 5mg the usual next rung. But four weeks is a guideline, not a countdown. Your prescriber decides the timing based on how you've actually got on, which is why two people who started on the same day can end up on different doses.
What tips the decision? If the first month went smoothly, with any nausea settling within a week or two, stepping up is often reasonable. If you're still queasy, or life threw you a rough patch, staying on 2.5mg a little longer is perfectly sensible. There's no prize for climbing fast, and rushing the titration tends to bring on the very side effects that make people stop. We walk through the specifics of that transition on our page about the move from 2.5mg to 5mg.
Some people ask why the dose has to go up at all. In short, the body adapts to a steady dose over time, and stepping up keeps the appetite effect useful; our explainer on why the dose increases covers the reasoning without turning it into a rule you must follow.
At nume, we don't hand you a self-service dial. A named prescriber reviews the evidence of how your treatment is going before agreeing any increase, and for repeat orders that review happens every time. You provide evidence of your current dose so the step-up is grounded in your real history, not guesswork. That check is deliberate.
How 5mg fits into the wider dose range up to 15mg
Mounjaro comes in six UK strengths: 2.5, 5, 7.5, 10, 12.5 and 15mg. Sitting second from the bottom, 5mg is early ground. Many people find their appetite response is already meaningful here, and some stay on it for a good while before any further change is considered. Others will step up again as their body adapts.
The trial evidence for tirzepatide comes largely from the SURMOUNT-1 study, which randomised more than 2,500 adults and reported average body-weight reductions of around 20 to 21 percent at the top 15mg dose over 72 weeks. Those headline figures reflect the highest dose taken over a long period, not what 5mg delivers in a month, so it's worth reading them for what they are. NICE assessed this evidence in its appraisal of tirzepatide (TA1026).
If you're curious how the next rung up compares, our page on 5mg versus 7.5mg sets the two side by side, and the broader picture of the full range of Mounjaro doses shows where each strength typically fits. Some people never need the higher doses at all; the aim is the effective dose for you, not the ceiling.
A practical note on the pen itself: each 5mg KwikPen holds four weekly doses and lives in the fridge, next to the milk in the door if that's easiest to remember. Details of the device are on our 5mg pen page.
Side effects to weigh when deciding on the 5mg step
Most tirzepatide side effects are gut-related and cluster around starting treatment or moving up a dose. Nausea is the one people mention most, alongside diarrhoea, constipation, indigestion, burping and the occasional bout of tiredness or headache. These tend to be at their most noticeable in the first days after a change and usually ease over the following week or two as the body adjusts.
Because 5mg is a step up, a short return of mild queasiness after the switch isn't unusual. Smaller, less rich meals, steady hydration and giving it a fortnight often help. If symptoms are severe, don't settle, or stop you keeping fluids down, that's a conversation with a clinician rather than something to push through. The NHS lists the common effects and self-care measures on its tirzepatide medicines page.
There's one uncommon but serious signal to know. In January 2026 the MHRA reminded prescribers and patients that acute pancreatitis is a rare side effect of GLP-1 medicines: severe stomach pain that reaches through to your back, with or without vomiting, needs urgent medical help. It's infrequent, but it's the one not to sit on.
Missing a dose around a step-up can also unsettle things; our page on missed dose side effects explains what tends to happen and when to seek advice. You can report any suspected side effect through the MHRA's Yellow Card scheme. Weighing tolerability against benefit is exactly the judgement a prescriber is there to help you make.
Who 5mg Mounjaro is licensed for in the UK
Mounjaro's UK licence for weight management covers adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, high cholesterol, prediabetes, type 2 diabetes or obstructive sleep apnoea. Lower BMI thresholds, around 2.5 kg/m² below the standard figures, can apply for people from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds under UK guidance.
Meeting a BMI number doesn't tick a box on its own. A prescriber looks at your full history, your other medicines and your goals before deciding whether tirzepatide is appropriate at all, let alone which dose. The 5mg strength isn't a separate licence; it's simply the dose you reach once you've started and titrated up under review.
Some groups shouldn't use it. It isn't recommended in pregnancy, when breastfeeding, or if you're trying to conceive, and it isn't licensed for under-18s. A history of pancreatitis, certain thyroid cancers or particular gut conditions all need a proper prescriber discussion before starting. If you're weighing your options generally, our overview of weight-loss treatment options is a calmer place to start than a dose page.
On contraception, there's a tirzepatide-specific point that catches people out. Because it can reduce how well the oral contraceptive pill is absorbed, women using the pill are advised to add a barrier method such as condoms for the first four weeks of treatment and for four weeks after each dose increase, including the step to 5mg. That's a real reason the timing of your step-up matters, and one our prescribers will flag.
NHS access versus a private prescription for 5mg
You can, in principle, be prescribed tirzepatide on the NHS, but access is tightly phased. NICE recommends it for adults with a BMI of 35 or more plus at least one weight-related condition, and the NHS is rolling it out in stages. As things stand, the earliest cohort covers people with a BMI of 40 or above who have four or more qualifying conditions, with broader groups phased in over the following years.
From April 2026 some GP practices can prescribe under the new contract, but participation is optional, so what's available depends heavily on your area and your practice. Everyone on the NHS route also takes part in wrap-around diet and activity support. NHS England sets out the criteria and the wider care on its weight-management injections page.
For many people, those thresholds are out of reach, or the wait is long. A private prescription through a regulated online pharmacy is the alternative: no referral, no waiting list, subject to a proper clinical assessment. That's the route nume offers. You can see current treatment and pricing on our weight-loss treatments page, where the one transparent price includes the consultation, the prescription and delivery.
Whichever route you take, the 5mg dose itself is the same medicine. The difference is how you reach it and who supervises the step. If you'd rather not sit on a waiting list, private care is legitimate; it simply needs to run through a pharmacy you can verify and a prescriber who assesses you properly.
What ordering 5mg through nume actually involves
If you decide 5mg is your step, here's how it works with us. You start with a free online consultation, answering questions about your health, history and current treatment. A GPhC-registered Independent Prescriber reads your answers the same day, not an algorithm, and decides whether tirzepatide and that dose are suitable for you. If you're already on treatment and stepping up, you provide evidence of your current dose so the increase is grounded in your real history.
We verify your identity with photo ID and confirm your weight on a short video call. Where it's appropriate, we notify your GP in line with GPhC guidance, so your wider care stays joined up. None of this is box-ticking; it's the safety scaffolding that separates a genuine pharmacy from the fake-pen sellers the MHRA keeps warning about.
Once you're clinically approved, the practical bit is quick. Order before 12pm on a weekday, before the school run if that's your window, and your treatment is dispatched the same day and delivered free the next working day by DPD, tracked, in plain unbranded packaging. There's no subscription and no auto-renewal; every repeat order is reviewed by a prescriber again. You can read more about who we are and meet our clinical lead if you'd like to know whose name sits behind the prescribing. When you're ready, speak to our prescribers and they'll tell you honestly whether 5mg is the right next step.
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