Quick answer. GLP-1 (and dual GIP/GLP-1) injections such as Wegovy (semaglutide), Saxenda (liraglutide) and Mounjaro (tirzepatide) slow stomach emptying and reduce appetite, helping people with obesity lose weight when combined with diet and exercise. In Singapore these are prescription-only medicines that must be doctor-supervised; they are approved for obesity (broadly BMI ≥30, or ≥27 with a weight-related condition – Asian cut-offs may be lower), not for cosmetic or minor weight loss. Weight is commonly regained if the medication is stopped, so treatment is often long-term; common side effects are nausea, vomiting and constipation. They are elective and paid out-of-pocket (not MediSave-subsidised for weight loss), typically costing several hundred to over a thousand Singapore dollars a month – always buy from a licensed clinic, never unregulated online sellers, which HSA has warned may be counterfeit.
Weekly and daily “weight-loss injection” pens have become one of the most talked-about treatments for obesity in Singapore. They belong to a class of medicines called GLP-1 receptor agonists (and, in Mounjaro’s case, a dual GIP/GLP-1 agonist). This guide explains how they work, which brands are approved by the Health Sciences Authority (HSA), who actually qualifies, what results to expect, the side effects and contraindications, and the typical monthly cost – so you can have an informed conversation with a doctor.
At a glance
| Medication | What it is / status | Typical cost (monthly) |
|---|---|---|
| Wegovy (semaglutide) | Weekly GLP-1 injection; HSA-approved for chronic weight management | ~S$350-S$1,000, depending on dose and clinic |
| Saxenda (liraglutide) | Daily GLP-1 injection; HSA-approved for weight management | ~S$400-S$700 at full 3 mg dose |
| Mounjaro (tirzepatide) | Weekly dual GIP/GLP-1 injection; HSA-approved (Jun 2025) for diabetes and weight management | Several hundred to ~S$1,000+, dose-dependent |
| Ozempic (semaglutide) | Weekly GLP-1 injection; HSA-approved for type 2 diabetes only (sometimes used off-label for weight) | Varies; prescription-only via licensed clinic |
How GLP-1 (and GIP/GLP-1) injections work
GLP-1 (glucagon-like peptide-1) is a natural gut hormone released after eating. The injections are receptor agonists – they mimic this hormone to produce two main effects relevant to weight:
- Slowed gastric emptying: food stays in the stomach longer, so you feel full sooner and for longer.
- Reduced appetite and food cravings: they act on appetite-regulating centres in the brain, lowering hunger and overall food intake.
Mounjaro (tirzepatide) is a dual agonist – it activates both the GIP and GLP-1 receptors, which in clinical trials has produced larger average weight loss than GLP-1 alone. These medicines also improve blood-sugar control, which is why the same drug classes are used to treat type 2 diabetes. They are an adjunct to – not a replacement for – a reduced-calorie diet and increased physical activity.
Which injections are available in Singapore and their HSA status
It is important to distinguish what each medicine is officially approved for, because some are used “off-label”:
- Wegovy (semaglutide), once-weekly: HSA-approved specifically for chronic weight management in adults with obesity or overweight with a weight-related condition. Launched in Singapore in 2025.
- Saxenda (liraglutide), once-daily: HSA-approved for weight management. An older GLP-1 option requiring a daily injection.
- Mounjaro (tirzepatide), once-weekly: a dual GIP/GLP-1 agonist. HSA first approved it for type 2 diabetes, and on 18 June 2025 also approved it for weight management in obesity/overweight with comorbidities.
- Ozempic (semaglutide), once-weekly: HSA-approved for type 2 diabetes, not for weight loss. It is sometimes prescribed off-label for weight, but it is not a licensed weight-management product in Singapore.
All of these are prescription-only medicines. They cannot be bought over the counter and must be supplied through a licensed clinic or pharmacy and supervised by a doctor.
Who qualifies – and who should not use them
These medicines are intended for the medical treatment of obesity, not for cosmetic slimming or losing a few kilograms. Doctors generally follow body-mass-index (BMI) criteria broadly aligned with international labelling:
- BMI ≥ 30 kg/m² (obesity), or
- BMI ≥ 27 kg/m² with at least one weight-related condition such as high blood pressure, type 2 diabetes or prediabetes, high cholesterol, or obstructive sleep apnoea.
Because Asian populations carry higher metabolic risk at a lower BMI, the WHO and local clinicians often use lower Asian cut-offs (for example, overweight from BMI 23 and obesity from about 27.5), so a doctor may consider treatment at a lower BMI. Treatment should always be paired with lifestyle changes. They are generally not suitable in pregnancy or breastfeeding, in people with a personal or family history of medullary thyroid cancer or MEN 2, or with certain pancreatic conditions – a doctor will screen for contraindications first.
Realistic results, side effects and stopping treatment
In clinical trials, average weight loss has reached roughly 15% of body weight with semaglutide and around 20% or more with tirzepatide over more than a year, alongside diet and exercise – though individual results vary.
Weight is commonly regained if you stop. In the STEP 1 trial extension, participants regained about two-thirds of their lost weight within a year of stopping semaglutide. Obesity is a chronic condition, so treatment is often long-term to maintain results.
Common side effects are gastrointestinal: nausea, vomiting, diarrhoea or constipation, and reduced appetite – usually worst when starting or increasing the dose, which is why doctors titrate slowly. Less common but serious risks include pancreatitis and gallbladder problems. Regulators including HSA continue to monitor the safety profile of this drug class. Doctor supervision is essential to manage dosing and side effects.
Cost and avoiding counterfeit pens
Weight-loss injections for obesity are considered elective and are paid out-of-pocket – they are not MediSave-claimable or subsidised when used for weight loss. Monthly cost depends on the drug, your dose (doses are titrated upward over weeks) and the clinic, and typically ranges from a few hundred to over a thousand Singapore dollars a month. Always confirm pricing, including consultation and GST, directly with the clinic.
HSA has repeatedly warned the public not to buy weight-loss products from unverified online sellers or social media. Such products may be counterfeit, adulterated or contain banned substances – HSA has reported cases of hospitalisation linked to illegal online weight-loss products. Buying or selling unregistered medicines is also an offence. Only obtain these injections through a licensed Singapore clinic or pharmacy after a proper medical assessment.
Related guides
- Best Bariatric & Weight-Loss Clinics in Singapore — our editorial shortlist
- bariatric & weight-loss clinics directory
- Bariatric surgery cost & MediSave
- Medical weight management options
- Ozempic vs Wegovy vs Mounjaro compared
Sources
- HSA – HSA alerts public to illegal weight-loss products purchased online
- HSA – Dubious weight-loss products sold online can harm your health
- DKSH – HSA approval of Mounjaro (tirzepatide) KwikPen in Singapore
- Wilding et al. – Weight regain after withdrawal of semaglutide (STEP 1 extension), Diabetes, Obesity and Metabolism
- SGH – Why can't we eat our fill and get our hands on Ozempic?
- HMI Medical – Understanding GLP-1 medications in Singapore
Related conditions & guides
Related conditions and guides you may find useful:
- Childhood Obesity in Singapore
- Fatty Liver Disease in Singapore
- Managing Type 2 Diabetes in Singapore
Part of our Weight & metabolic health guides · Browse all health topics