Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician, Doctor Bangkok.
Last reviewed: October 2026
Both Ozempic (semaglutide) and Mounjaro (tirzepatide) are weekly injection treatments available in Bangkok by prescription only. Tirzepatide produced greater average weight loss in a direct head-to-head trial. But the better choice depends on your medical history, current health status, and how your body responds. A screening consultation before you start either drug is the responsible first step.
You want to know which one to be on and whether you can get it here. Both drugs work. Tirzepatide tends to produce more weight loss on average in trials. But neither is right for everyone, and Bangkok supply makes the practical side of this decision matter as much as the clinical side.
Before any prescription is written, a doctor needs to check your history, your current medications, and whether stock for your preferred option is realistic right now. That screening is available same-day at Doctor Bangkok.

Semaglutide vs Tirzepatide: What Each Drug Actually Does
Ozempic contains semaglutide. It acts on one receptor: GLP-1, a hormone that slows digestion and reduces appetite. Mounjaro contains tirzepatide. It acts on two receptors: GLP-1 and GIP. That dual action is why tirzepatide tends to produce stronger appetite suppression in many patients.
Both drugs lower blood sugar and slow gastric emptying. Semaglutide has cardiovascular outcome data from the SUSTAIN-6 and SELECT trials, showing it reduces the risk of major cardiac events in high-risk patients. Tirzepatide’s cardiovascular outcome trial, SURPASS-CVOT, reported results in 2025. It showed tirzepatide was non-inferior to dulaglutide for major cardiac events in patients with type 2 diabetes and established cardiovascular disease, and was associated with lower all-cause mortality, though it did not show superiority for the primary endpoint. Semaglutide’s SELECT trial enrolled patients without diabetes, so the two cardiovascular datasets cover different populations. If cardiac risk is a factor for you, it is worth checking your numbers with our Cardiovascular Risk Calculator before your consultation.
Both drugs require dose escalation over several weeks. That titration schedule is not optional. It is what determines how well you tolerate either drug from the start.
What the Trial Data Actually Shows on Ozempic vs Mounjaro Weight Loss
In the STEP trials for semaglutide and the SURMOUNT trials for tirzepatide, both drugs produced meaningful weight loss compared to placebo. SURMOUNT-5 is the most relevant data point here. It was a direct head-to-head comparison of tirzepatide against semaglutide in adults with obesity but without type 2 diabetes. Tirzepatide produced greater average weight loss. That is a real finding from a real trial, not a cross-trial estimate.
Why Individual Results Still Vary
Trial averages include people who responded very well and people who responded less well. Your result depends on your starting weight, your metabolic profile, how consistently you use the drug, and how you manage diet alongside it. Some people lose more on semaglutide than the tirzepatide average. Comparing your progress against trial data is useful for setting expectations, not for predicting your personal outcome.

Side Effects and Tolerability: What to Expect
The most common side effects for both drugs are nausea, vomiting, diarrhoea, and constipation. These are gastrointestinal effects linked to slower stomach emptying. They tend to be worst during dose escalation and improve as the body adjusts.
There is no clear head-to-head evidence showing one drug causes fewer gastrointestinal side effects than the other at equivalent doses. What the data does show is that a slower titration schedule reduces side effect severity for both. Rushing the dose increase is the main reason people stop early.
Both drugs carry a warning for patients with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2. Neither drug should be started in those patients. Pancreatitis history, gallbladder disease, severe kidney impairment, and pregnancy are also reasons to pause before prescribing.
Buying either drug without a consultation is a real risk, not a formality. Our GLP-1 service page covers mounjaro vs ozempic side effects and monitoring in more detail.
Availability and Practical Factors in Bangkok
Both semaglutide and tirzepatide are prescription-only in Thailand. Neither can be legally bought over the counter. Both are primarily registered for type 2 diabetes by the Thai FDA. Prescribing for weight loss is off-label, which means a physician must document clinical justification: typically a BMI above a defined threshold, metabolic risk factors, or a history of prior interventions that have not worked.
Supply in Bangkok can shift. Both drugs are import-dependent, and pharmacy stock for specific pen strengths can be inconsistent month to month. If you are planning treatment around a fixed stay, whether you are an expat on a long-term contract or a visitor with a three-week window, this matters.
If your preferred drug is unavailable, a doctor can advise on switching or managing a short pause safely. Self-sourcing from unverified pharmacies carries a real risk of counterfeit product, which is a documented issue with high-demand GLP-1 medications globally. Doctor Bangkok monitors stock and can advise before you start.
How a Screening Consultation Helps You Choose
The decision between semaglutide and tirzepatide is not one to make based on an article alone. It requires a review of your BMI, your current medications (several drugs interact with GLP-1 agents), your thyroid and pancreatic history, and a blood glucose baseline.
At Doctor Bangkok, we run that screening as a same-day consultation. You can get a quick BMI estimate beforehand with our BMI Calculator. We review your blood glucose, discuss which drug fits your profile, confirm the right starting dose, and explain how to titrate safely. If a contraindication comes up, we tell you clearly and discuss what alternatives are available.
This is what makes the difference between a drug that works safely and one that causes problems in the first two weeks.
Book a Comparison Consultation at Doctor Bangkok
If you are in Bangkok now and want to start, walk in. Doctor Bangkok is open 24 hours, seven days a week, on Sukhumvit Soi 13, BTS-accessible. No appointment needed.
If you would rather not travel, our doctor hotel visit service means a physician comes to you within one hour, anywhere in Bangkok. This is useful if you are fitting your first consultation between other plans, or if you want a doctor nearby for your first injection.
For ongoing prescriptions, monitoring, and follow-up, our weight-loss injections service covers everything from initial assessment through to review appointments. We are doctor-led, English-speaking, and available around the clock.
Not sure whether Ozempic or Mounjaro is right for you? Doctor Bangkok offers same-day GLP-1 screening consultations at our central Bangkok clinic on Sukhumvit Soi 13, open 24 hours. If you would prefer a doctor at your hotel or condo, our mobile doctor service reaches you anywhere in Bangkok within one hour. Walk in anytime or contact us to arrange an in-room visit before your first injection.
FAQ
Dr. Ponlawat Pitsuwan
Physician, Doctor Bangkok
a private medical clinic in central Bangkok open 24 hours, seven days a week, with a doctor-on-call service that reaches your hotel or condo within one hour. He sees expats, residents, and medical tourists for weight management, metabolic health, GLP-1 prescribing, and general medical care. His approach is straightforward, evidence-based care delivered in plain language.
References
- Aronne LJ, et al. Tirzepatide versus Semaglutide for Obesity (SURMOUNT-5). New England Journal of Medicine, 2025.
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine, 2021.
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine, 2022.
- Lincoff AM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT). New England Journal of Medicine, 2023.
- TCTMD. SURPASS-CVOT Published: Large Trial Confirms CVD Efficacy of Tirzepatide. 2025.
- Marso SP, et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes (SUSTAIN-6). New England Journal of Medicine, 2016.
The information in this article is for educational purposes only and does not constitute medical advice. It should not be used to self-diagnose or replace a consultation with a qualified physician. If you have concerns about your health, contact a licensed medical professional. For appointments at Doctor Bangkok, visit doctorbangkok.co.th.




