Best Doctor-Prescribed Weight Loss Medications in Singapore

86.4% of trial participants lost clinically significant weight on semaglutide — but it is not the only option

In the landmark STEP 1 trial, 86.4% of patients taking semaglutide 2.4 mg lost more than 5% of their body weight over 68 weeks. That number stands out because most diets produce the opposite: temporary loss followed by regain.

But semaglutide is not the only prescription weight loss medication available in Singapore. Depending on your medical history, goals, and budget, your doctor might recommend a GLP-1 medication, phentermine, naltrexone-bupropion, or orlistat — each with different mechanisms, timescales, and trade-offs.

This guide covers every major doctor-prescribed weight loss medication available in Singapore, with clinical evidence, realistic expectations, pricing, and how they compare. Whether you are exploring GLP-1 treatments like Ozempic or wondering about older options like Duromine, you will find the facts you need to have a better conversation with your doctor.

GLP-1 medications: the current standard

GLP-1 receptor agonists are the most effective class of weight loss medication available today. They mimic a natural gut hormone called glucagon-like peptide-1 (GLP-1), which regulates appetite, blood sugar, and satiety.

Unlike older weight loss drugs that work through stimulant effects or fat blocking, GLP-1 medications target the hormonal root of overeating. They reduce hunger signals in the brain, slow gastric emptying so food stays in your stomach longer, and quiet what patients call "food noise" — the constant mental chatter about food.

Several GLP-1 medications are prescribed in Singapore.

Semaglutide: Ozempic, Wegovy, and Rybelsus

Semaglutide is the active ingredient in three brand-name medications:

• Ozempic — weekly injection, maximum dose 1 mg, approved for Type 2 diabetes but widely prescribed off-label for weight loss
• Wegovy — weekly injection, maximum dose 2.4 mg, specifically approved for weight management
• Rybelsus — daily oral tablet, 14 mg, approved for Type 2 diabetes

In the STEP 1 trial (Wilding et al., New England Journal of Medicine, 2021), semaglutide 2.4 mg produced 14.9% mean body weight loss over 68 weeks. 69.1% of participants lost more than 10% of their body weight, and 50.5% lost more than 15%.

At the lower Ozempic dose (1 mg), weight loss is more moderate but still clinically meaningful. The STEP 2 trial showed 9.6% weight loss in patients with Type 2 diabetes.

Rybelsus produces more modest weight loss at the currently approved 14 mg dose (around 3-5%). Higher-dose oral semaglutide formulations (25-50 mg) are in development and show results closer to injectable efficacy.

Common side effects: Nausea, diarrhoea, constipation, and reduced appetite — typically mild and improving over the first few weeks at each dose level.

Cost in Singapore: $350-$650 per month at Trimly (all-inclusive: consultation, medication, delivery, and unlimited follow-ups). Other providers may charge $500-$900+ when consultation and follow-up fees are added separately.

Tirzepatide: Mounjaro

Tirzepatide (brand name Mounjaro) is a dual incretin agonist. It activates both the GLP-1 receptor and the GIP receptor (glucose-dependent insulinotropic polypeptide), and in trials it has produced stronger weight loss than any GLP-1-only medication.

In the SURMOUNT-1 trial (Jastreboff et al., New England Journal of Medicine, 2022), tirzepatide at 15 mg produced 20.9% mean body weight loss over 72 weeks — roughly 40% more than semaglutide in cross-trial comparison. At 10 mg, the result was 19.5%.

Tirzepatide is available as a weekly injection with doses ranging from 2.5 mg to 15 mg. In Singapore, availability is more limited than semaglutide, and it typically costs between $600 and $1,200 per month depending on the clinic and dose.

Common side effects: Similar gastrointestinal profile to semaglutide — nausea, diarrhoea, constipation. The gradual dose titration over 20 weeks helps minimise these effects.

Liraglutide: Saxenda

Liraglutide (brand name Saxenda) is an older GLP-1 medication that requires daily injections rather than weekly. The SCALE Obesity trial (Pi-Sunyer et al., New England Journal of Medicine, 2015) showed approximately 8% mean body weight loss over 56 weeks.

Saxenda has largely been replaced by semaglutide and tirzepatide, which produce more weight loss with less frequent dosing. Your doctor may still consider it if newer medications are not suitable for you.

Phentermine: Duromine and Panbesy

Phentermine is one of the most commonly prescribed weight loss medications in Singapore. It has been around for decades. It is a sympathomimetic amine, which means it increases norepinephrine levels in the brain to suppress appetite.

In Singapore, phentermine is available under two brand names:

• Duromine — slow-release capsules (15 mg and 30 mg)
• Panbesy — immediate-release capsules (15 mg and 30 mg)

What the evidence shows

Phentermine typically produces 5-10% body weight loss in the short term. That is meaningful, but the critical limitation is the timeframe: it is approved for a maximum of 12 weeks of use because its appetite-suppressing effects diminish over time and the side effect profile makes long-term use inadvisable.

Who gets prescribed phentermine in Singapore

Phentermine is widely prescribed by GPs in Singapore as a first-line weight loss medication because it is familiar, inexpensive (around $3-5 per capsule), and produces noticeable short-term results. If you have visited a GP for weight management, there is a good chance phentermine was offered.

Side effects and limitations

Because phentermine works through the sympathetic nervous system (the fight-or-flight response), its side effects reflect that mechanism:

• Increased heart rate and blood pressure
• Insomnia and restlessness
• Dry mouth
• Dizziness

It is contraindicated in patients with cardiovascular disease or uncontrolled hypertension, and it is not suitable for long-term use.

How phentermine compares to GLP-1 medications

The difference comes down to duration and mechanism. Phentermine forces appetite suppression through stimulant pathways for a few weeks. GLP-1 medications work through hormonal pathways that regulate hunger at a biological level and can be used long-term. If you need sustained weight loss rather than a short-term push, GLP-1 medications are the stronger option.

That said, phentermine has a role. Some doctors prescribe it as a short-term bridge while patients wait to start GLP-1 treatment, or for patients who need a lower-cost option and understand the temporary nature of the results.

Naltrexone-bupropion: Contrave

Contrave combines two medications: naltrexone (an opioid antagonist) and bupropion (an antidepressant). Together they target the brain's reward and hunger centres.

How it works

Naltrexone blocks opioid receptors involved in food reward, the part of your brain that makes certain foods feel pleasurable beyond actual hunger. Bupropion increases norepinephrine and dopamine activity, which reduces appetite and can improve mood. The combination dampens the reward-driven eating that many people struggle with.

Clinical evidence

The COR-I trial (Greenway et al., The Lancet, 2010) showed approximately 6% mean body weight loss in patients taking naltrexone-bupropion. When combined with intensive behavioural therapy (COR-BMOD), results improved to 9.3%. Placebo-subtracted, that is about 4.8-5.2% more weight loss than without the medication.

Availability in Singapore

Contrave received HSA approval in January 2022. It is available through some clinics — Siena Health, for example, offers it online. It is taken as an oral tablet, which appeals to patients who prefer not to inject.

Who is it suitable for

Contrave may be a reasonable option if:

• You experience significant reward-driven or emotional eating
• You have tried GLP-1 medications and cannot tolerate them
• You prefer oral medication over injections

Who should not take it

Contrave is contraindicated in patients with:

• Seizure disorders
• Current opioid use (naltrexone blocks opioid receptors)
• Eating disorders (bulimia or anorexia nervosa)
• Uncontrolled hypertension
• Use of MAOIs within 14 days

How it compares

Contrave produces less weight loss than GLP-1 medications (approximately 6% versus 15-22%) and does not address hormonal hunger the way GLP-1 agonists do. It is a legitimate option, but the results are more modest and the mechanism is different.

Orlistat: Xenical

Orlistat works differently from everything else on this list. Instead of reducing hunger, it blocks fat absorption in the gut.

How it works

Orlistat is a lipase inhibitor. It blocks the enzyme that breaks down dietary fat, preventing your body from absorbing approximately 30% of the fat you eat. That unabsorbed fat passes through your digestive system, which produces the side effects this medication is known for.

Clinical evidence

Clinical trials show orlistat produces 8-10% total body weight loss when combined with a reduced-calorie diet, though the placebo-subtracted difference is more modest at approximately 2.9% (Torgerson et al., Diabetes Care, 2004).

Xenical (120 mg) is available by prescription in Singapore. An over-the-counter version called Alli (60 mg) exists in some markets, but its OTC availability in Singapore has not been confirmed through HSA — your pharmacist or doctor can clarify the current status.

Side effects

Orlistat's side effects are directly tied to its mechanism:

• Oily or fatty stools
• Increased bowel urgency
• Flatulence with oily spotting
• Abdominal discomfort

These effects are worse after high-fat meals — which, proponents argue, teaches patients to reduce dietary fat intake. In practice, many patients find the gastrointestinal effects difficult to live with.

How it compares

Orlistat does not reduce hunger, change hormonal signalling, or affect how your brain processes food cravings. It just reduces how much fat your body absorbs. The weight loss is more modest, and the side effects put many patients off. It can work for people who eat a high-fat diet and are willing to change their eating to minimise GI symptoms, but it is rarely a first choice when GLP-1 options are available.

How these medications compare

This table puts all six medications side by side.

What this table tells you

Semaglutide and tirzepatide produce substantially more weight loss than the alternatives and address hormonal hunger rather than just symptoms. Phentermine works short-term but cannot be sustained. Contrave and orlistat are options for patients who cannot use GLP-1 medications, but the results are more modest.

For most patients who qualify, GLP-1 treatment is the most effective option. If it is not suitable for you due to contraindications, cost, or personal preference, your doctor may recommend one of these alternatives based on your health profile.

Who qualifies for prescription weight loss medication in Singapore

In Singapore, the MOH clinical practice guidelines recommend pharmacotherapy for weight management when:

• BMI 30 or above without additional conditions
• BMI 27.5-29.9 with at least one weight-related condition (Type 2 diabetes, hypertension, high cholesterol, PCOS, or obstructive sleep apnoea)

These thresholds are lower than Western guidelines because Asian populations face higher metabolic risk at lower BMI levels.

At Trimly, our doctors can prescribe GLP-1 medications for patients with:

• BMI 27.5 or above without weight-related conditions
• BMI 24 or above with weight-related conditions

Your doctor will assess your full medical history, current medications, and treatment goals during the consultation to determine which medication is most appropriate.

How to get prescribed weight loss medication in Singapore

Weight loss medications are prescription-only in Singapore. You cannot buy them over the counter or from unregulated online sources. Here are the legitimate routes.

In-clinic consultation

Visit a GP or specialist (endocrinologist, obesity medicine doctor) for a face-to-face assessment. The doctor will evaluate your BMI, medical history, and suitability for medication. This works well if you prefer in-person visits, but requires scheduling appointments for every follow-up.

Telehealth consultation

Licensed telehealth providers offer the same medical evaluation via video call. At Trimly, the process works like this:

1. Complete an online health questionnaire (about five minutes)
2. Video consultation with a licensed Singapore doctor
3. Receive your personalised treatment plan
4. Medication delivered to your door
5. Unlimited follow-up support via video or WhatsApp

For a detailed walkthrough, read our step-by-step guide to getting prescribed weight loss medication.

Frequently asked questions

What is the most effective prescription weight loss medication?

Based on current clinical evidence, tirzepatide (Mounjaro) has produced the largest weight loss in trials — 20.9% at 72 weeks. Semaglutide (Wegovy/Ozempic) is a close second at 14.9% over 68 weeks. Both are GLP-1-class medications and significantly outperform older options like phentermine, Contrave, and orlistat.

Is Duromine still prescribed in Singapore?

Yes. Phentermine (sold as Duromine and Panbesy) remains widely prescribed by GPs in Singapore, typically as a short-term option. It is limited to 12 weeks of use and produces 5-10% weight loss. For longer-term treatment, GLP-1 medications are generally more effective.

Can I take weight loss pills instead of injections?

Several prescription options come in pill form: Rybelsus (oral semaglutide), Contrave (naltrexone-bupropion), Xenical (orlistat), and Duromine/Panbesy (phentermine). However, the most effective medications — injectable semaglutide and tirzepatide — currently require weekly injections. Higher-dose oral semaglutide formulations approaching injectable efficacy are in development.

How much do weight loss medications cost in Singapore?

Costs vary widely. Phentermine (Duromine) is the cheapest at around $90-150/month. GLP-1 medications range from $350-650/month (semaglutide at Trimly) to $600-1,200/month (tirzepatide). Contrave is typically $200-400/month. For a detailed cost breakdown, see our guide to GLP-1 weight loss costs.

Are weight loss medications covered by Medisave or insurance?

Generally, no. Medications prescribed primarily for weight loss are typically not covered by Medisave or standard health insurance in Singapore. If a medication like Ozempic is prescribed for its approved indication (Type 2 diabetes), partial coverage may apply depending on your insurer.

What are the side effects of weight loss medication?

Side effects depend on the medication class. GLP-1 medications primarily cause gastrointestinal effects (nausea, diarrhoea, constipation) that typically improve over time. Phentermine can increase heart rate and blood pressure. Contrave may cause nausea and headaches. Orlistat causes GI effects related to fat malabsorption. Your doctor will discuss the specific risk profile for any medication they recommend.

Making the right choice

There is no single "best" weight loss medication for everyone. The right choice depends on your medical history, the amount of weight you need to lose, how long you have been struggling, your budget, and your preferences around pills versus injections.

The evidence points clearly to GLP-1 medications as the most effective option for most people who qualify. Semaglutide and tirzepatide produce the most weight loss and work through hormonal pathways that directly address why you feel hungry. The other medications have their place, but the gap in efficacy is large.

A doctor who knows the full range of options can help you weigh the trade-offs. At Trimly, our doctors specialise exclusively in GLP-1 weight loss treatment and can walk you through the decision. Every patient gets unlimited follow-up support, home medication delivery, and responsive doctor access via WhatsApp.

This article is for informational purposes only and does not constitute medical advice. Always consult your doctor before starting, stopping, or changing any medication. Individual results may vary. Clinical trial results are based on controlled study conditions and may not reflect real-world outcomes. Weight loss results vary depending on individual factors including starting weight, adherence, diet, and exercise. The figures cited in this article come from specific trial populations and dosing regimens. Trimly is a MOH-licensed telehealth clinic in Singapore (HCSA License R/25M0505/MDS/001/252).