Ozempic vs Wegovy vs Mounjaro: Which Weight Loss Medication Is Right for You?

More GLP-1 options than ever, and that changes how you choose

A few years ago, people looking into medical weight loss had one or two options. Today, the conversation around Ozempic vs Wegovy and Ozempic vs Mounjaro reflects something bigger: there are now multiple clinically proven GLP-1 medications available in Singapore, each with different strengths, dosing formats, and trial data behind them. And we finally have a head-to-head comparison. The SURMOUNT-5 trial, published in the NEJM in May 2025, directly compared tirzepatide and semaglutide for the first time.

More options is good news. It means your doctor can match a medication to your health profile, preferences, and goals rather than offering a one-size-fits-all approach. But more choice also brings more confusion. Which medication produces the most weight loss? Is an injection better than a pill? Does "newer" mean "better"?

This article breaks down the evidence behind Ozempic, Wegovy, Mounjaro, and Rybelsus so you can walk into a consultation informed, not overwhelmed. We cover how each medication works, what the clinical trials actually show, what they cost in Singapore, and how to think about choosing between them. The goal is not to tell you which medication to take. That is your doctor's role. The goal is to help you understand your options so you can have a better conversation about what fits your situation.

Why there are multiple GLP-1 options (and why that matters)

All GLP-1 medications share a common thread: they work by mimicking hormones your body already produces to regulate appetite and blood sugar. But the similarities end there. Different medications target different receptors, come in different formats, and have been studied in different populations.

Semaglutide is the molecule behind three brand names: Ozempic (injectable, approved for type 2 diabetes), Wegovy (injectable, approved for weight management), and Rybelsus (oral tablet, approved for type 2 diabetes). Same active ingredient, different doses and indications.

Tirzepatide is the molecule behind Mounjaro. Unlike semaglutide, which targets only the GLP-1 receptor, tirzepatide is a dual agonist that activates both GLP-1 and GIP receptors. This "twincretin" approach is why you will sometimes see it described as a next-generation medication.

Having multiple options matters because weight loss is not a uniform problem. Some people respond better to one molecule than another. Some cannot tolerate injections. Some need a medication that also addresses type 2 diabetes. A doctor who understands all the available options can recommend the right fit, not just the most well-known one.

For a broader look at how these medications work at the hormonal level, see our guide to weight loss medication.

Quick comparison: Ozempic vs Wegovy vs Mounjaro vs Rybelsus

Costs are approximate ranges across Singapore providers. Trimly offers all-in pricing from $350-650/month, see our cost breakdown guide for details.

Ozempic: The most recognised name

Ozempic brought GLP-1s into the mainstream. It contains semaglutide and is administered as a once-weekly injection. Though technically approved for type 2 diabetes, not weight management, it is widely prescribed off-label for weight loss in Singapore and worldwide.

Strengths:
- Extensive real-world data. Ozempic has been on the market since 2017, giving doctors years of experience with its safety profile
- Weekly injection is convenient, one pen click per week
- Effective for people with type 2 diabetes who also want to lose weight (the STEP 2 trial showed 9.6% weight loss in patients with type 2 diabetes at 68 weeks)
- Available in doses up to 2 mg for diabetes management

Limitations:
- Standard doses (0.5-1 mg) produce less weight loss than Wegovy's 2.4 mg maintenance dose, which caps its weight loss potential when used at lower doses
- Officially an off-label use for weight management, which may affect insurance coverage
- Same side effect profile as all GLP-1s: nausea, vomiting, diarrhoea, and constipation, particularly during dose escalation

Best for: People with type 2 diabetes who want weight loss alongside blood sugar control. Also a reasonable starting point for those whose doctors prefer a lower semaglutide dose.

For a deeper look at how Ozempic works, eligibility, and what to expect, read our complete Ozempic guide for Singapore.

Wegovy: The weight-loss-specific semaglutide

Wegovy is the same molecule as Ozempic, semaglutide, but formulated and dosed specifically for weight management. The maintenance dose is 2.4 mg weekly, more than double Ozempic's standard 1 mg dose. This higher dose is what was used in the STEP clinical trials.

Strengths:
- The strongest clinical evidence for semaglutide-based weight loss. In the STEP 1 trial, participants lost an average of 14.9% of their body weight over 68 weeks (Wilding et al., NEJM 2021)
- Strong responder rates: 86.4% lost more than 5%, 69.1% lost more than 10%, and 32% lost more than 20%
- Long-term data from STEP 5 showed 15.2% weight loss sustained at 104 weeks (Garvey et al., Nat Med 2022)
- Approved specifically for weight management, not an off-label use
- Gradual dose titration (0.25 mg, 0.5 mg, 1.0 mg, 1.7 mg, 2.4 mg) helps manage side effects

Limitations:
- Supply constraints have affected availability in some markets
- Higher cost than Ozempic in some cases due to the weight management indication
- Not ideal for those who cannot tolerate injections (consider Rybelsus instead)

Best for: People whose primary goal is weight loss and who want the most established injectable semaglutide option with dedicated weight management approval.

For full details on dosing, eligibility, and availability, see our Wegovy guide for Singapore.

Mounjaro: The dual-action option

Mounjaro (tirzepatide) takes a different approach. While semaglutide activates only the GLP-1 receptor, tirzepatide is a dual GLP-1 and GIP receptor agonist, often called a "twincretin." This dual mechanism appears to amplify both appetite suppression and metabolic improvements beyond what GLP-1 alone achieves.

Strengths:
- The highest weight loss numbers in clinical trials to date. In the SURMOUNT-1 trial (Jastreboff et al., NEJM 2022), tirzepatide at 15 mg produced 20.9% body weight loss at 72 weeks (ITT), with 22.5% in the on-treatment analysis
- Even the lowest dose (5 mg) produced 15.0% weight loss, comparable to Wegovy's highest dose
- At 15 mg, 39.7% of participants achieved 25% or more weight loss (efficacy estimand)
- Significant metabolic improvements: triglycerides reduced by 20-25% and systolic blood pressure reduced by 6-8 mmHg
- Confirmed superiority in the head-to-head SURMOUNT-5 trial: tirzepatide achieved 20.2% weight loss vs semaglutide's 13.7% at 72 weeks
- Flexible dosing from 2.5 mg to 15 mg allows doctors to find the right balance between efficacy and tolerability

Limitations:
- Newer medication with less long-term, real-world data compared to semaglutide
- Higher cost in Singapore ($600-1,200/month) compared to semaglutide options
- Availability can be limited depending on the provider

Best for: People looking for the highest potential weight loss and whose doctors consider them good candidates for a dual-action medication. Also worth discussing for those who have not achieved their goals on semaglutide alone.

Read our full Mounjaro and tirzepatide guide for Singapore for more on how this medication works.

Rybelsus: The oral option for those who prefer pills

Not everyone is comfortable with injections, and that is a perfectly valid preference. Rybelsus (oral semaglutide) offers a needle-free alternative. It is taken as a daily tablet on an empty stomach, at least 30 minutes before food or other medications.

At the current approved dose of 14 mg daily, Rybelsus produces more modest weight loss, around 3-5% in the PIONEER trials, which studied patients with type 2 diabetes. Newer high-dose oral formulations are showing much stronger results though. The OASIS trials found that 25 mg oral semaglutide produced 13.6% weight loss at 64 weeks, and 50 mg produced 15.1% at 68 weeks, approaching injectable efficacy.

Strengths:
- No injections required
- Daily routine may feel more natural for some patients
- Effective for blood sugar control in type 2 diabetes
- Newer high-dose formulations closing the gap with injectables

Limitations:
- Current 14 mg dose produces significantly less weight loss than injectable options
- Must be taken on an empty stomach with a small sip of water, and timing can be inconvenient
- Higher-dose formulations (25-50 mg) not yet widely available

Best for: People who strongly prefer pills over injections, particularly if they also have type 2 diabetes. Rybelsus can also work as a starting point for patients who want to try a GLP-1 medication before committing to injectables. Some doctors use it as an initial step to see how a patient responds to the GLP-1 class. For those focused primarily on weight loss, discussing oral vs injectable GLP-1 options with a doctor can help clarify the trade-offs.

For more on the oral option, read our Rybelsus guide for Singapore.

Head-to-head: What the clinical trials actually show

When comparing semaglutide vs tirzepatide, we now have both individual trial data and a direct head-to-head comparison.

Semaglutide (STEP trials)

• STEP 1: 14.9% weight loss at 68 weeks in people with overweight or obesity without diabetes
• STEP 2: 9.6% at 68 weeks in people with type 2 diabetes
• STEP 5: 15.2% at 104 weeks (two years), showing sustained results
• Responder rates (STEP 1): 86.4% lost more than 5%, 69.1% lost more than 10%, 50.5% lost more than 15%, 32% lost more than 20%

Tirzepatide (SURMOUNT trials)

• SURMOUNT-1, 5 mg: 15.0% weight loss at 72 weeks
• SURMOUNT-1, 10 mg: 19.5% at 72 weeks
• SURMOUNT-1, 15 mg: 20.9% at 72 weeks
• Responder rates (15 mg): 39.7% achieved 25% or more weight loss (efficacy estimand)

The head-to-head: SURMOUNT-5

The SURMOUNT-5 trial (published NEJM, May 2025) directly compared tirzepatide and semaglutide at their maximum tolerated doses over 72 weeks. The results were clear: tirzepatide produced 20.2% weight loss versus semaglutide's 13.7%, a 47% greater reduction. Tirzepatide also showed lower rates of gastrointestinal side effects leading to discontinuation (2.7% vs 5.6%).

This is the first randomised, head-to-head comparison, which means we no longer need to rely solely on cross-trial comparisons with their inherent limitations (different patient populations, durations, and baseline characteristics).

Side effects compared

Both semaglutide and tirzepatide share a similar side effect profile, which is typical of GLP-1 medications:

• Nausea is the most common side effect for both, usually worst during dose escalation
• Vomiting, diarrhoea, and constipation are gastrointestinal effects that tend to be mild to moderate
• Side effects typically improve after four to eight weeks as the body adjusts

The gradual dose titration schedules for both medications are designed to minimise these effects. Most patients find that side effects are manageable, particularly with guidance from their doctor on diet adjustments during titration.

Decision framework: How to think about choosing

Rather than asking "which GLP-1 is the best," the more useful question is: "which GLP-1 is best for my situation?" Here is a framework to guide your thinking before you speak with a doctor.

Do you prefer pills over injections?
If needles are a real barrier, Rybelsus offers an oral alternative. The trade-off is lower weight loss at current doses (3-5% at 14 mg), though newer high-dose formulations are closing that gap. Discuss the latest options with your doctor.

Is maximum weight loss your primary goal?
The SURMOUNT-1 and SURMOUNT-5 trial data for tirzepatide (Mounjaro) consistently shows the highest average weight loss, up to 20.9% at the 15 mg dose. If your doctor considers you a candidate for tirzepatide, it offers the greatest potential based on current evidence.

Do you value an extensive track record?
Semaglutide has been studied more widely and for longer than tirzepatide. If your doctor, or you, prefer a medication with years of real-world safety data, Wegovy or Ozempic may be the more comfortable choice.

Do you also have type 2 diabetes?
Ozempic and Mounjaro are both approved for type 2 diabetes, meaning they can address blood sugar control and weight simultaneously. Your doctor can help determine which is more appropriate based on your metabolic profile.

What is your budget?
Cost matters. In Singapore, oral semaglutide (Rybelsus) typically ranges from $350-500/month, injectable semaglutide from $500-900/month, and tirzepatide from $600-1,200/month. Providers vary significantly. Some charge separate consultation and medication fees, while others offer all-in pricing.

Are you already on a GLP-1 and not seeing the results you expected?
Switching between GLP-1 medications is more common than you might think. Some patients who plateau on semaglutide see renewed progress after switching to tirzepatide, or vice versa. If your current medication is not delivering the results you hoped for, that does not mean GLP-1 treatment does not work for you. It may mean a different option is worth exploring with your doctor.

The most important factor: your doctor's recommendation.
Every person's health profile is different. Existing conditions, medications, metabolic markers, and treatment history all influence which medication is safest and most effective. A doctor who takes the time to assess your individual situation will make a better recommendation than any comparison chart.

Why the "best" medication is the one your doctor recommends

Reading trial data and concluding that the medication with the highest weight loss percentage is automatically the best choice is tempting but misguided. Clinical decisions are more nuanced than that.

Your doctor considers factors that no comparison article can account for: your kidney function, thyroid history, current medications, how you have responded to previous treatments, and whether you have contraindications like a history of medullary thyroid carcinoma or MEN 2. They also weigh practical factors like whether you can commit to weekly injections, whether the medication is available, and whether the cost is sustainable for you long-term.

All GLP-1 medications in this comparison are clinically proven to produce meaningful weight loss. The difference between 15% and 21% matters less than whether you can tolerate the medication, afford it consistently, and maintain it over time with proper medical support. A medication that works well and that you can stay on will always beat one that looks better on paper but does not fit your life.

This is also why gradual dose titration matters. Your doctor will start you on a low dose, monitor how you respond, adjust based on your side effects and progress, and find the dose that balances results with tolerability. For Wegovy, that means stepping from 0.25 mg up to 2.4 mg over about 16 weeks. For Mounjaro, it means starting at 2.5 mg and increasing by 2.5 mg every four weeks as tolerated. That personalised, step-by-step approach is worth far more than choosing a medication based on trial averages.

For more on what doctors assess before recommending a GLP-1 medication, see our guide on factors doctors check before prescribing GLP-1.

Getting personalised advice through Trimly

Trimly is a MOH-licensed telehealth clinic in Singapore focused exclusively on GLP-1 weight loss treatment. Our doctors assess your health profile through a video consultation and recommend the medication, and dose, that makes the most sense for your individual situation.

Here is how it works:

1. Complete a short online questionnaire covering your health history, current medications, and goals
2. Video consultation with a doctor who reviews your profile, discusses options, and recommends a treatment plan
3. Medication delivered to your door with no clinic visits or pharmacy queues
4. Ongoing support including unlimited free follow-up consultations plus responsive doctor support via WhatsApp

Trimly offers transparent, all-in pricing from $350-650/month. That includes the consultation, medication, delivery, and all follow-ups. No hidden fees, no surprise charges.

Whether your doctor recommends semaglutide, tirzepatide, or an oral option, you will have ongoing medical support to manage dose adjustments, side effects, and progress tracking. The right medication is only part of the equation. How it is managed matters just as much.

What to remember

• Ozempic, Wegovy, and Mounjaro are all clinically proven GLP-1 medications with strong weight loss evidence
• Wegovy (semaglutide 2.4 mg) produced 14.9% weight loss in the STEP 1 trial, the established standard for injectable semaglutide
• Mounjaro (tirzepatide 15 mg) produced 20.9% weight loss in SURMOUNT-1 and confirmed its superiority over semaglutide in the SURMOUNT-5 head-to-head trial
• Rybelsus offers a needle-free option with more modest results at current doses, though newer formulations are closing the gap
• The right medication depends on your individual health profile, not trial averages. Your doctor's recommendation matters most.

Individual results vary. All GLP-1 medications require a doctor's assessment and prescription. Contraindications include pregnancy, breastfeeding, personal or family history of medullary thyroid carcinoma, and MEN 2. Discuss your full medical history with your doctor before starting treatment.