Both are weekly injections. Both switch off the hunger noise. Both are now easy to find in Lagos — and both are being sold by people who should not be selling them. Here is the honest comparison we give clients at our Lekki Phase 1 clinic, with the trial numbers, the side-effect differences, and what each actually costs.
The 30-second version
Semaglutide was first, has the longer safety record, and is the cheaper of the two. Tirzepatide came later, produces more weight loss on average, and is usually the one people want once they have read the trial numbers. Both are serious prescription medicines that need a medical check before you start and supervision while you are on them.
How they work — and why tirzepatide tends to win on the scale
After you eat, your gut releases hormones that tell your brain you are full. Two of them matter here:
- GLP-1 slows how quickly your stomach empties, lowers appetite and improves how your body handles blood sugar.
- GIP works alongside GLP-1 on appetite and on how fat tissue handles energy.
Semaglutide copies GLP-1 only. Tirzepatide copies both GLP-1 and GIP. That dual action is the main reason tirzepatide moves the scale further for most people, and the reason some people find it slightly easier on the stomach for the same result.
What the trials actually showed
These are the headline numbers from the large published trials in adults with obesity, without diabetes, on the highest doses, alongside diet and exercise advice:
| Trial | Medicine and dose | Average weight loss |
|---|---|---|
| STEP 1 (68 weeks) | Semaglutide 2.4 mg weekly | about 15% of body weight |
| SURMOUNT-1 (72 weeks) | Tirzepatide 15 mg weekly | about 21% of body weight |
| SURMOUNT-5 (72 weeks, head-to-head) | Tirzepatide vs semaglutide, each at the highest tolerated dose | about 20% vs about 14% |
For a 100 kg person, that is roughly the difference between losing 14 kg and 20 kg over a year and a half. Two things to keep in mind: these are averages (some people lose much more, some much less), and they are at full dose after a slow build-up of several months. Nobody loses 20% in 8 weeks, on either medicine.
Side effects: same family, slightly different feel
Both medicines cause the same group of effects, because both slow your stomach down:
- Nausea, especially in the first 1–2 weeks after each dose increase
- Constipation (more common on semaglutide in our experience) or diarrhoea
- Feeling full after a few bites, burping, reflux
- Tiredness in the first month
- Injection-site redness
Less common but important on both: gallbladder problems, pancreatitis, low blood sugar if combined with insulin or sulfonylureas, and dehydration from vomiting. Both carry a warning about thyroid C-cell tumours seen in rodents, which is why a personal or family history of medullary thyroid cancer rules them out.
In the head-to-head trial, the proportion of people who stopped because of side effects was similar on both. The practical difference is that semaglutide's nausea tends to be front-loaded at each step-up, while tirzepatide's is often milder but can come with more fatigue early on. Our guide to handling GLP-1 nausea and what to eat applies to both.
Dosing and the pace of the first three months
| Semaglutide | Tirzepatide | |
|---|---|---|
| Start | 0.25 mg weekly × 4 weeks | 2.5 mg weekly × 4 weeks |
| Maintenance range | 0.5–2.4 mg | 5–15 mg |
| Step size | roughly doubles early on | +2.5 mg per step |
| Minimum time per step | 4 weeks | 4 weeks |
Tirzepatide's smaller, more even steps give a clinician more room to find the dose where you lose steadily without feeling sick. That is a real, everyday advantage, not just a trial statistic.
Cost in Lagos: like for like
Prices in Nigeria move with the exchange rate and with supply, so we keep ours on one page — the Services & Pricing page, every figure VAT-inclusive — rather than printing numbers in an article that will date. What matters is comparing like for like:
- A branded pen (Ozempic or Mounjaro) is four weekly doses; Mounjaro is priced above Ozempic everywhere in the world, and the higher strengths cost more than the starting strength.
- An in-clinic weekly shot of tirzepatide or semaglutide is priced per shot and per dose step, and a four-week level costs less than four single shots.
- A monthly program bundles the shots with IV drips and B12 and is the lowest cost per shot; the two- and three-month programs are lower still per month.
Two honest notes on cost. First, the cheaper option that makes you quit in week three is the expensive one. Second, whatever you pay, you are paying for a medicine that only works while you take it — so the plan for what happens after the program (habits, maintenance dosing, or tapering) matters as much as the brand.
So which should you choose?
Lean towards tirzepatide (Mounjaro) if:
- You have a lot of weight to lose (roughly 20 kg or more) or you have struggled to get results on semaglutide
- You have pre-diabetes or type 2 diabetes alongside weight — tirzepatide's blood-sugar effect is stronger
- You can commit to the higher monthly cost for the full course
Lean towards semaglutide (Ozempic/Wegovy/compounded) if:
- Budget is the deciding factor and you would rather stay consistent on something affordable
- You have a smaller goal (5–15 kg) or want a lower-intensity first experience of a GLP-1
- You have a specific reason your clinician prefers it (for example, certain heart-risk profiles where semaglutide has published cardiovascular outcome data)
Neither, without a proper check, if:
- You are pregnant, breastfeeding or planning to conceive in the next few months
- You or a close relative has had medullary thyroid cancer or MEN2
- You have had pancreatitis, or you have an eating disorder that is not in treatment
- You are using it to lose a few kilos before an event — the first month is the hardest part, and you would be stopping just as the benefit starts
A word about where you buy it
Lagos is full of Instagram pages and chemists selling "Mounjaro" and "Ozempic" at prices that do not add up. The risks are real: pens that were never kept cold, re-labelled vials, and doses nobody has calculated. Both medicines are only safe when the product is genuine, the cold-chain is intact, and someone qualified is deciding your dose and watching for problems.
At The Baddie Lab, every GLP-1 program starts with a consultation with our medical team, uses products from licensed pharmacies, and includes weekly check-ins as your dose changes. If you are unsure which medicine fits you, that consultation is the fastest way to a real answer. You can also read our GLP-1 weight loss page or our guide on how to take the shot.
Questions people ask
Is Mounjaro the same as Ozempic?
No. Mounjaro is tirzepatide; Ozempic is semaglutide. They are different molecules from different companies (Eli Lilly and Novo Nordisk). They are in the same family of weekly injectable medicines and are used in similar ways.
Is Wegovy the same as Ozempic?
Same medicine (semaglutide), different pen and dose range. Ozempic is licensed for type 2 diabetes and goes up to 2 mg; Wegovy is the weight-loss version and goes up to 2.4 mg. Zepbound is the weight-loss version of Mounjaro in the same way.
Which has fewer side effects, Mounjaro or Ozempic?
Both cause the same kinds of stomach side effects. In trials, rates of nausea and vomiting were broadly similar at comparable stages; many clinicians find tirzepatide slightly better tolerated for the amount of weight lost. Individual reactions vary a lot — some people do better on one than the other.
Can I switch from Ozempic to Mounjaro?
Yes, under medical supervision. You do not simply swap at the same number: your clinician will choose a tirzepatide starting dose based on how long you have been on semaglutide and how you tolerated it, and will time the first tirzepatide shot a week after your last semaglutide dose.
Is Mounjaro available in Nigeria?
Yes. Mounjaro pens are available in Lagos through licensed pharmacies and clinics, including ours. Because demand is high, counterfeit and improperly stored pens exist. Buy only from a clinic or pharmacy that can show you the cold-chain and the source.
Do I need to be diabetic to use these?
No. Semaglutide and tirzepatide are approved for chronic weight management in adults with obesity (BMI 30+), or BMI 27+ with a weight-related condition such as high blood pressure, high cholesterol, sleep apnoea or pre-diabetes. A consultation confirms whether you qualify and whether it is safe for you.
This article is general information for people in Nigeria and is not a diagnosis or a treatment plan. Treatments at The Baddie Lab are only started after a consultation with our medical team. Results vary from person to person. If you have a medical emergency, go to the nearest hospital.