What strength Mounjaro do I need for weight loss?

You've just been approved, why does it start at 2.5mg?

Picture the moment your Mounjaro arrives. You open the box, read the leaflet, and the first pen reads 2.5mg. If you were hoping to hit the ground running at a higher strength, that figure can feel underwhelming. It isn't. The 2.5mg starting dose exists because tirzepatide (the active ingredient) slows how quickly the stomach empties and suppresses appetite through two gut-hormone pathways simultaneously. Starting at the top would, for most people, mean significant nausea from day one. The first four weeks are your body's settling-in period.

The NHS medicines guidance on tirzepatide confirms that 2.5mg is a tolerability dose and is not intended as the maintenance strength. Once you have completed four weeks at 2.5mg, your prescriber reviews your response and, if you have tolerated it well, the dose typically steps up to 5mg. From that point, each subsequent increase follows the same logic: four weeks minimum at the current strength, a clinical review, then a considered step upward if it is appropriate. Skipping steps is not how the licensed schedule works, and a prescriber who knows this will not rush you through.

At nume, no dose increase is issued without fresh clinical review, your response and any side effects are assessed before your next pen is dispensed. You can read more about the 5mg dose specifically, including what to expect when the first real therapeutic step begins.

What actually determines which strength is right for you?

There is no blood test or formula that produces the perfect Mounjaro dose. What a prescriber weighs up is more practical: how you tolerated the previous strength, whether side effects were manageable, how your appetite and weight have responded, and whether any other medicines or health conditions are in the picture. The decision to increase your dose is not automatic at four weeks, it is conditional on tolerability.

Some people reach a comfortable maintenance strength well below 15mg. Others need to reach the top of the range before seeing the results the clinical trials demonstrated. NICE's appraisal of tirzepatide notes that if a patient has not lost at least 5% of their body weight after six months at the highest tolerated dose, continuing treatment should be reviewed. That threshold is a clinical checkpoint, not a punishment, it helps ensure the treatment is doing what it is supposed to do for you specifically.

Lower body weight, age, other medicines and individual GI sensitivity all shift the picture. Some people find that 7.5mg or 10mg is the sweet spot where appetite suppression is effective and side effects are minimal. There is no universally correct answer, which is exactly why a one-size prescription without clinical oversight is not safe practice. You can find a full breakdown of all six Mounjaro strengths and what distinguishes each one.

Side effects at different strengths, what the evidence shows

Gastrointestinal side effects are most common when a new dose is introduced. Nausea, loose stools, indigestion and reduced appetite tend to peak in the first week or two after a dose step, then ease. The SURMOUNT-1 trial, published in the New England Journal of Medicine, found that GI events were the most frequently reported reason for discontinuation, though rates remained relatively low at maintenance doses. Most people who reached 15mg had tolerated the lower doses first, giving their system time to adapt.

If side effects are significant at a given strength, the right clinical response is often to stay at that dose longer rather than push upward, or, in some cases, to step back down temporarily. Pushing through severe symptoms to reach a higher dose faster is not clinically appropriate and is not something a careful prescriber would recommend. Keep your pen stored where you will actually remember it. Many patients find putting it in the fridge door alongside everyday items (rather than at the back of a shelf) is the cue that makes the weekly routine stick.

The NHS medicines information for tirzepatide lists the full side-effect profile and explains which symptoms warrant contacting a healthcare professional promptly. Our frequently asked questions also cover what to do if side effects feel unmanageable at a particular dose.

Deciding whether to stay, step up or pause, the prescriber's role

The highest strength (15mg) produces the greatest average weight reduction in clinical evidence, but it is not the target for everyone, and reaching it is not the definition of success. Your prescriber's job is to find the highest strength you tolerate well, and that might be 10mg. It might be 12.5mg. What matters is a sustained, clinically supervised response, not a number on the pen. For a fuller picture of how the doses compare in practice, the Mounjaro strength guide on our site covers the clinical rationale for each step in plain language.

People transferring to nume from another provider, or returning after a break, go through a clinical review before any dose is confirmed. A prescriber assesses whether the dose you were previously on is still appropriate given the time elapsed and your current health picture. Starting back at a lower strength after a gap is common, and sensible. The available tirzepatide strengths page explains the full licensed range and the circumstances in which each is typically used.

If you are trying to work out where you might sit on the dose ladder, the most useful thing is a conversation with a prescriber who can look at your full picture. The cost of treatment at various stages is one practical consideration, you can explore that on our treatment page. Speak to our prescribers to get a clinical view on which starting point makes sense for you.