Retatrutide (Reta) is not yet proven stronger than Mounjaro (tirzepatide): its own trials reported larger average weight loss, but no trial comparing the two directly has reported results. In TRIUMPH-1, average weight change was −25.0% at 80 weeks on retatrutide 12 mg (Jastreboff 2026); in SURMOUNT-1, −20.9% at 72 weeks on Mounjaro 15 mg (Jastreboff 2022). Mounjaro is registered in Singapore; retatrutide is not. Individual results vary.
Retatrutide and orforglipron are not registered in Singapore, and GetLean does not prescribe or supply them. GetLean does prescribe and supply HSA-registered GLP-1 medications, after a consultation with Dr Quek. Mounjaro is one of them: at GetLean it is from S$488 a month (S$788 depending on dose, S$1,088 at the max dose), all-in, and the first step is a 30-minute video consultation with Dr Quek.
For tirzepatide (Mounjaro):
Availability in Singapore. This medicine is registered with Singapore's Health Sciences Authority, and its registered indication includes weight management. Which medicine suits a particular person, if any does, is decided by the doctor who assesses them.
For retatrutide:
Availability in Singapore. This is an investigational medicine. It is not registered with Singapore's Health Sciences Authority, and it has no approved application with the United States Food and Drug Administration either, so it cannot be prescribed in either country. Outside clinical trials, Lilly releases it only through a pre-approval expanded access programme for a small group of adults with severe obesity who cannot join a trial, on their own doctor's request and where Lilly makes it available, and anything offered for sale under this name is not what the trials studied.
Education only. This page is general education about two medicines, one of which is not registered in Singapore. GetLean does not prescribe or supply retatrutide, and nothing here recommends using it.
Has any trial compared retatrutide with Mounjaro directly?
Not with results yet. TRIUMPH-5, a phase 3, double-blind trial, randomised an estimated 800 adults with obesity to retatrutide or tirzepatide, with weight change at week 80 as its main measure. Its registry entry estimates primary completion in November 2026 and study completion in December 2026, and when it was read on 25 October 2026 no results were posted (ClinicalTrials.gov). A search of PubMed the same day found no published trial of the two medicines against each other.
Until such a trial reports, every answer to "which is stronger" sets separate trials side by side, or pools them indirectly. Both are set out below, with the reasons neither settles it.
What did each medicine's main trial find?
Retatrutide 12 mg averaged −25.0% at 80 weeks in TRIUMPH-1, and tirzepatide 15 mg −20.9% at 72 weeks in SURMOUNT-1, each tested against placebo in adults with obesity and without diabetes.
| TRIUMPH-1 (retatrutide) | SURMOUNT-1 (tirzepatide, Mounjaro) | |
|---|---|---|
| Who took part | 2,339 adults with obesity, without diabetes | 2,539 adults with obesity, or overweight with at least one weight-related complication, without diabetes |
| Average starting weight | 112.7 kg (Lilly's topline announcement) | 104.8 kg |
| Length | 80 weeks | 72 weeks |
| Weekly doses | 4 mg, 9 mg, 12 mg | 5 mg, 10 mg, 15 mg |
| How the result was counted | Everyone randomised (treatment-regimen estimand) | Everyone randomised (treatment-regimen estimand) |
| Average weight change | −17.6%, −23.7%, −25.0% | −15.0%, −19.5%, −20.9% |
| Placebo | −3.9% | −3.1% |
| Stopped because of side effects | 4.1%, 6.9%, 11.3%, against 4.9% on placebo (topline announcement) | 4.3%, 7.1%, 6.2%, against 2.6% on placebo |
| Funded by | Eli Lilly | Eli Lilly |
Figures by dose, lowest to highest. TRIUMPH-1: Jastreboff 2026, with the starting weight and stopping rates from Lilly, May 2026. SURMOUNT-1: Jastreboff 2022. Individual results vary and are not guaranteed.
Why the columns are not a ranking. TRIUMPH-1 ran eight weeks longer, and its participants started about 8 kg heavier on average. Reading −25.0% against −20.9% as the difference between the medicines treats two separate measurements as one.
Where the −28.3% comes from. The figure often quoted for retatrutide is Lilly's result for 12 mg counted as if everyone had stayed on treatment, against −2.2% on placebo (Lilly, May 2026). It is a different count from the −25.0% in the table, which includes everyone randomised whether or not they kept taking it.
What about people with type 2 diabetes?
The averages are lower for both medicines, and their trials in adults with type 2 diabetes and a BMI of 27 or more were again separate and placebo-controlled. In TRIUMPH-2, 1,152 adults with obesity and type 2 diabetes averaged −11.9%, −16.8% and −18.8% on retatrutide 4 mg, 9 mg and 12 mg at 80 weeks, against −5.1% on placebo (Bellido 2026). In SURMOUNT-2, 938 adults with a BMI of 27 or more and type 2 diabetes averaged −12.8% and −14.7% on tirzepatide 10 mg and 15 mg at 72 weeks, against −3.2% on placebo (Garvey 2023).
Both trials counted everyone randomised. They still differ in length and in who took part, so the same caution applies. Individual results vary and are not guaranteed.
Which has more side effects, retatrutide or Mounjaro?
No trial comparing them directly has reported side-effect results yet. In both medicines' trials, the most common side effects were digestive (Jastreboff 2026; Jastreboff 2022).
In Lilly's topline announcement of TRIUMPH-1, nausea was reported by 42.4% on retatrutide 12 mg against 14.8% on placebo, and dysesthesia, an unusual skin sensation, by 5.1%, 12.3% and 12.5% across the three doses against 0.9% on placebo; 11.3% on 12 mg stopped because of side effects, against 4.9% on placebo (Lilly, May 2026). In SURMOUNT-1, 6.2% on tirzepatide 15 mg stopped because of side effects, against 2.6% on placebo (Jastreboff 2022).
The retatrutide side-effects page and the Mounjaro side-effects page set out each medicine's figures in full.
What do pooled analyses of the trials suggest?
They give different estimates, and both stress uncertainty. A 2026 network meta-analysis in BMJ Medicine pooled 58 trials of 24,214 adults without diabetes, searched to 6 March 2026, and estimated weight change against placebo of −22.10% for retatrutide and −19.28% for tirzepatide. Its authors noted overlapping confidence intervals for several comparisons, limited head-to-head evidence, and low-certainty evidence that more people stopped retatrutide (Chen 2026).
A larger 2026 analysis in the BMJ, of 262 trials, compared each drug with lifestyle measures alone at one year and estimated −14.9% for tirzepatide with moderate to high certainty, and 13.1% to 14.6% for newer agents including retatrutide, with very low to low certainty (Nong 2026).
The BMJ Medicine analysis searched for trials up to 6 March 2026, before TRIUMPH-1's paper was published on 29 September 2026. Neither analysis is a trial of the two medicines against each other. Individual results vary.
How do retatrutide and Mounjaro work differently?
Mounjaro (tirzepatide) acts at two hormone receptors, GIP and GLP-1 (Jastreboff 2022); retatrutide acts at those two and a third, glucagon (Jastreboff 2026). Both were given as once-weekly injections under the skin in their trials. How retatrutide works covers the three receptors, and the half-life, in more detail.
Is retatrutide available in Singapore?
No. Retatrutide and orforglipron are not registered in Singapore, and GetLean does not prescribe or supply them. GetLean does prescribe and supply HSA-registered GLP-1 medications, after a consultation with Dr Quek.
A full download of Singapore's register of therapeutic products, read on 25 October 2026 (5,511 records, approvals up to 8 July 2026), contains no retatrutide product (HSA register), and HSA's listing of approvals, last updated on 21 October 2026, has none among approvals to September 2026 (HSA approvals). HSA said on 25 September 2026 that no regulatory authority, including HSA, had approved retatrutide as a medicine (HSA 2026), and the US FDA's database held no application for it on 24 October 2026 (Drugs@FDA).
Outside its trials, Lilly lists a pre-approval expanded access programme, first posted on 5 June 2026, for a small group of adults with severe obesity who cannot join a trial, on their own doctor's request (ClinicalTrials.gov NCT07629401). Products sold online as "Reta" are a different matter, covered on is Reta legal in Singapore?.
Is Mounjaro available in Singapore?
Yes, on a doctor's prescription. Tirzepatide is on Singapore's register as 18 injection products named Mounjaro (HSA register), and on its current registrations its indications include weight management as well as type 2 diabetes (Singapore NDF).
Mounjaro also has a direct comparison of its own. In SURMOUNT-5, a trial that compared tirzepatide with semaglutide directly, average weight change at 72 weeks was −20.2% on tirzepatide against −13.7% on semaglutide; the trial was open-label (Aronne 2025). Wegovy vs Mounjaro sets out that trial. Individual results vary and are not guaranteed.
What does Mounjaro cost at GetLean?
At GetLean, Mounjaro is from S$488 a month (S$788 depending on dose, S$1,088 at the max dose), all-in: Dr Quek's video consultations and reviews, the medication delivered to you, and daily WhatsApp coaching. The first step is a 30-minute video consultation with Dr Quek for S$20, refunded in full if he decides medication is not right for you, and a consultation does not guarantee a prescription. Mounjaro in Singapore has the price for each dose.
For the medicines Dr Quek prescribes, the plan for coming off is the GetLean GLP-1 Taper Plan: he steps the dose down at monthly reviews towards the lowest effective dose and, where clinically appropriate, off the medication.
Book your consult with Dr Quek.
Read the transcript
Is Reta stronger than Mounjaro? Is retatrutide stronger than tirzepatide?
Not proven. Reta's own trials reported larger average weight loss, but no trial comparing the two directly has reported results.
I'm Dr Quek, a Singapore-registered doctor, and the doctor behind the GetLean GLP-1 Taper Plan.
Retatrutide and orforglipron are not registered in Singapore, and GetLean does not prescribe or supply them.
What did each medicine's main trial find?
On retatrutide's highest dose, the average weight loss was about twenty-five percent; on Mounjaro's, about twenty-one.
That is not a ranking: retatrutide's trial ran eight weeks longer, and its participants started about eight kilos heavier on average.
You may also hear twenty-eight percent for retatrutide: that's Lilly's result for the highest dose, counted as if everyone had stayed on treatment.
Has any trial compared them directly?
Not with results yet: TRIUMPH-5 is a phase three, double-blind trial that randomised an estimated eight hundred adults with obesity to retatrutide or tirzepatide.
Its registry entry estimates the main part will finish in November twenty twenty-six, but that is an estimate, not a date for results.
Until it reports, any answer to which is stronger sets separate trials side by side, or pools them indirectly, and neither settles it.
Which has more side effects, retatrutide or Mounjaro?
No trial comparing them directly has reported side-effect results yet. In both medicines' trials, the most common side effects were digestive.
How do they work differently?
Mounjaro, that's tirzepatide, acts at two hormone receptors, GIP and GLP-1. Retatrutide acts at those two and a third, glucagon.
That is the difference: the number of hormone receptors each acts at.
Is either one available in Singapore?
Mounjaro is available, on a doctor's prescription: tirzepatide is on Singapore's register as injection products named Mounjaro, and its registered indications include weight management.
Anything offered for sale under the Reta name is not what the trials studied.
Whether it suits a particular person is a doctor's decision, after an assessment.
If you're considering GLP-1 medication to reach your weight goal, and you'd like to taper off it one day, I invite you to visit getleanclinic.sg to learn about our approach and the GetLean GLP-1 Taper Plan.
Common questions
Is Reta stronger than Mounjaro?
Not proven. Retatrutide (Reta) reported larger average weight loss in its own trials, but no trial comparing it directly with tirzepatide (Mounjaro) has reported results. In TRIUMPH-1, average weight change was −25.0% at 80 weeks on retatrutide 12 mg (Jastreboff 2026); in SURMOUNT-1, it was −20.9% at 72 weeks on tirzepatide 15 mg (Jastreboff 2022). The trials differ in length and in who took part. Individual results vary and are not guaranteed.
When will the TRIUMPH-5 results come out?
No date is set. TRIUMPH-5's registry entry estimates primary completion in November 2026 and study completion in December 2026, and those are estimates, not a results date. When the entry was read on 25 October 2026, no results were posted (ClinicalTrials.gov).
Is Reta available in Singapore?
No. Retatrutide and orforglipron are not registered in Singapore, and GetLean does not prescribe or supply them. GetLean does prescribe and supply HSA-registered GLP-1 medications, after a consultation with Dr Quek. A full download of Singapore's register, read on 25 October 2026, has no retatrutide product (HSA register), and HSA said on 25 September 2026 that no regulatory authority, including HSA, had approved it as a medicine (HSA 2026).
Which has more side effects, retatrutide or Mounjaro?
No trial comparing them directly has reported side-effect results yet. In both medicines' trials, the most common side effects were digestive. In TRIUMPH-1, 11.3% on retatrutide 12 mg stopped because of side effects, against 4.9% on placebo, in Lilly's topline announcement (Lilly, May 2026); in SURMOUNT-1, 6.2% on tirzepatide 15 mg stopped, against 2.6% (Jastreboff 2022).
What is the difference between retatrutide and tirzepatide?
The number of hormone receptors each acts at. Tirzepatide (Mounjaro) acts at two, GIP and GLP-1 (Jastreboff 2022); retatrutide acts at those two and a third, glucagon (Jastreboff 2026). Both were given as once-weekly injections in their trials.
Is Mounjaro registered in Singapore for weight loss?
Yes. On its current registrations, tirzepatide, sold as Mounjaro, carries a weight-management indication as well as a type 2 diabetes indication in Singapore (Singapore NDF). Whether it suits a particular person is a doctor's decision after an assessment.