Is Trulicity the Same as Mounjaro? What You Need to Know Before Switching

You have a Trulicity pen in your hand and you are wondering whether Mounjaro is the same thing

It is a question that arrives for a few different reasons. Maybe your pharmacist mentioned tirzepatide in passing. Maybe a news article described Mounjaro's weight-loss results and you recognised some similarities with the pen you already use. Or perhaps your GP has suggested changing your treatment and you are trying to understand what is actually different.

Trulicity is the brand name for dulaglutide, made by Eli Lilly, the same manufacturer as Mounjaro. That shared origin causes some of the confusion. Dulaglutide is a GLP-1 receptor agonist: it mimics a gut hormone called glucagon-like peptide-1, which helps regulate blood sugar and slows how quickly the stomach empties. It was approved in the UK for type 2 diabetes and has been in clinical use here for several years.

Mounjaro contains tirzepatide, a newer and structurally distinct molecule. Where dulaglutide targets one receptor, tirzepatide targets two: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). Activating both pathways together produces a stronger effect on appetite regulation and blood-sugar control than either alone. This dual action is why tirzepatide's clinical trial results looked different from those of earlier GLP-1 medicines, and why it earned a separate UK licence for weight management in adults with a BMI of 30 or above, or 27 or above alongside at least one weight-related health condition. You can read more about tirzepatide's licensed uses and how the dual mechanism works in practice.

The short version: same manufacturer, same injection format, entirely different medicine.

What the licences actually cover, and why that gap matters

In the UK, every medicine's licence defines what it can lawfully be prescribed for. Trulicity's licence covers type 2 diabetes. It has not been assessed by the MHRA or NICE for weight management, so a prescriber in the UK cannot offer it for that purpose, regardless of any emerging evidence elsewhere.

Mounjaro holds two separate UK licences. The first, for type 2 diabetes, covers its use in blood-sugar management. The second, for weight management, is the one that has attracted most attention: NICE recommended tirzepatide for adults with obesity under specific criteria in its appraisal TA1026, published in December 2024. The NHS is rolling out access in phases, prioritising people with higher BMIs and multiple weight-related conditions. Many people who meet the licence criteria but not the current NHS thresholds are accessing Mounjaro privately, through regulated pharmacies, following a clinical consultation. The Mounjaro overview page covers the eligibility picture in more detail.

This distinction matters practically. If you are using Trulicity for diabetes and your prescriber is considering Mounjaro, the clinical rationale will be different from that for someone starting Mounjaro purely for weight management. Switching between medicines in the same broad class still requires a full prescriber review, not a like-for-like swap.

The NHS tirzepatide page explains what Mounjaro is approved for, who it is suitable for, and what monitoring is involved, worth reading before your next appointment.

Side-effect profiles: similar territory, different specifics

Because both medicines slow gastric emptying, the side-effect overlap is real. Nausea, loose stools, constipation, indigestion and reduced appetite are common to both. For most people these are most noticeable in the first few weeks or after a dose increase, then settle. That said, the profiles are not identical, and the doses and titration schedules are different for each, so direct experience comparisons between friends or online communities are only loosely informative.

There are a few practical considerations that apply specifically to Mounjaro. Women taking the oral contraceptive pill should use an additional barrier method for the first four weeks of treatment and for four weeks after each dose increase, because tirzepatide's effect on gastric emptying can reduce pill absorption. NHS guidance also suggests discussing transdermal HRT options (patches or gels) with your doctor if you are on hormone replacement therapy. These points are worth raising early if they apply to you, our prescribers at nume cover them as part of every clinical review.

For a broader look at how Mounjaro interacts with other medicines you might be taking alongside it, the guide to medicines and supplements alongside Mounjaro is a useful starting point, and your prescriber or pharmacist can advise on anything specific to your situation.

So which medicine is right for you?

That is genuinely a clinical question, not one this page or any website can settle. The relevant factors include your diagnosis, your current treatment, your BMI, other health conditions, and what you are trying to achieve. If weight management is the goal, Mounjaro is currently the only injectable medicine with a UK licence for that purpose at Mounjaro's dose range; Trulicity is not an option in that context. If blood-sugar control is the priority and you are already stable on Trulicity, your diabetes team is the right first call about whether a switch makes sense.

If you are considering Mounjaro for weight management through a private route, a consultation with a registered prescriber is the starting point. At weight loss treatment options, you can see the treatments available and how the process works. Costs vary by dose and provider; the Mounjaro price comparison guide gives an honest picture of what the UK private market looks like right now, including what to watch for when comparing quotes.

If you have questions before starting, the FAQs cover the most common ones, and our clinical team is reachable through the contact page. When you are ready, check your eligibility and a GPhC-registered prescriber will review your consultation the same day.