Treatment Comparison
Mounjaro vs Wegovy: Which Weight Loss Treatment Is Better?
Quick Answer: Both Mounjaro (tirzepatide) and Wegovy (injectable semaglutide 7.2 mg) are MHRA-approved once-weekly weight loss injections available through GPhC-registered UK pharmacies. Mounjaro produces modestly higher average weight loss — approximately 22.5% vs approximately 19–21% with Wegovy 7.2 mg in their respective landmark trials. Wegovy 7.2 mg is the newest and most potent injectable semaglutide dose, approved following the STEP UP trial (2025), and considerably narrows the efficacy gap with Mounjaro compared with earlier semaglutide doses. From 2025/26, Wegovy is also available as a once-daily oral tablet (up to 25 mg). For most patients seeking maximum weight loss, Mounjaro remains the stronger clinical choice, though Wegovy 7.2 mg now offers a compelling alternative within the GLP-1 class.~19–21%avg weight loss with Wegovy 7.2 mg (STEP UP trial)
13.6%avg weight loss with oral semaglutide 50 mg (OASIS 1 — 25 mg expected less)
~£30per month cheaper: Mounjaro maintenance vs Wegovy
Full Head-to-Head
Mounjaro vs Wegovy: Complete Comparison (2026)
The table below compares every clinically relevant dimension of Mounjaro and Wegovy, including the latest 2026 UK pricing and the oral semaglutide tablet (up to 25 mg) development.
| Factor | Mounjaro (Tirzepatide) | Wegovy (Semaglutide) |
|---|---|---|
| Drug class | GLP-1 / GIP dual agonist | GLP-1 receptor agonist only |
| Active ingredient | Tirzepatide | Semaglutide 7.2 mg (injectable) |
| Manufacturer | Eli Lilly | Novo Nordisk |
| UK licence | MHRA approved 2023; NICE TA1026 | MHRA approved 2021; NICE TA875 (7.2 mg STEP UP 2025) |
| Starting dose | 2.5 mg/week | 0.25 mg/week |
| Maintenance dose | 15 mg/week | 7.2 mg/week |
| Dose steps | 6 steps over ~20 weeks | 4 steps over ~16 weeks; further step to 7.2 mg |
| Administration | Once-weekly injection (auto-pen) | Once-weekly injection (pen) |
| Half-life | ~5 days | ~7 days |
| Avg weight loss (flagship trial) | ~22.5% at 15 mg (SURMOUNT-1, 72 wks) | ~19–21% at 7.2 mg (STEP UP, 72 wks) |
| Head-to-head (SURMOUNT-5) | ~20.2% weight loss | ~13.7% (semaglutide 2.4 mg arm — not 7.2 mg) |
| NHS availability | Limited — NICE TA1026 criteria | Limited — NICE TA875 criteria |
| Starting price (UK 2026) | ~£133/month (2.5 mg) | ~£149/month (0.25 mg) |
| Maintenance price (UK 2026) | ~£285/month (15 mg) | ~£299/month (7.2 mg) |
| Oral formulation available? | No — injection only | Yes — oral tablet up to 25 mg once daily (2025/26) |
How They Work
GLP-1 vs Dual GLP-1/GIP: Why the Mechanism Matters
Both treatments belong to the GLP-1 receptor agonist class, but they act on different receptor combinations — and this distinction has meaningful clinical consequences for efficacy, metabolic effects and tolerability.
Wegovy: GLP-1 Receptor Agonist
Wegovy contains semaglutide — a synthetic analogue of the naturally occurring GLP-1 hormone, engineered for once-weekly dosing with a half-life of approximately seven days. GLP-1 receptors are distributed throughout the gut, pancreas and brain. Semaglutide's agonism of these receptors slows gastric emptying, reduces appetite, enhances glucose-dependent insulin secretion and suppresses glucagon — producing meaningful weight loss and metabolic improvements in the majority of patients.
Semaglutide has been in clinical use for type 2 diabetes (as Ozempic, 1 mg) since 2017 and for weight management (as Wegovy, initially 2.4 mg) in the UK since 2021. The 7.2 mg dose — approved following the STEP UP trial in 2025 — is now the highest approved injectable semaglutide dose for weight management, giving clinicians a more potent option within the same GLP-1 class.
Mounjaro: Dual GLP-1/GIP Receptor Agonist
Mounjaro contains tirzepatide — a novel dual agonist designed to activate both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors simultaneously. GIP is a gut-derived incretin hormone that, in combination with GLP-1, produces appetite suppression and insulin sensitisation through complementary and partially non-overlapping pathways. The GIP receptor contribution is why Mounjaro produces greater average weight loss than semaglutide at comparable clinical doses, and why its insulin-sensitising effects are more pronounced.
Tirzepatide was originally developed for type 2 diabetes (as Mounjaro at lower doses) before its remarkable weight loss efficacy in SURMOUNT-1 led to its development as a weight management treatment. In the UK, it received MHRA approval for weight management in November 2023, with NICE recommending it in 2024 (TA1026).
Why the Dual Mechanism Matters
The practical consequence of GIP co-agonism is visible in the clinical data: Mounjaro produces approximately 22.5% weight loss at 15 mg versus approximately 19–21% with Wegovy 7.2 mg. While Wegovy 7.2 mg substantially narrows the efficacy gap compared with the 2.4 mg dose, Mounjaro's dual mechanism still confers a modest advantage in average weight loss and a more pronounced insulin-sensitising effect — particularly relevant for patients with significant insulin resistance.
Clinical Efficacy
Weight Loss Results: Landmark Trial Comparison
The most clinically important difference between Mounjaro and Wegovy is the magnitude of weight loss each produces. This difference is consistent across multiple data sources.
*Absolute weight loss in STEP UP is higher partly reflecting a higher mean starting weight in that trial population.
| Outcome | Mounjaro 15 mg (SURMOUNT-1) | Wegovy 7.2 mg (STEP UP) |
|---|---|---|
| Mean weight loss at trial end | ~22.5% at 72 weeks | ~19–21% at 72 weeks |
| Achievement of ≥5% weight loss | 91% | >91% |
| Achievement of ≥10% weight loss | 83% | ~80% |
| Achievement of ≥15% weight loss | 73% | ~63% |
| Achievement of ≥20% weight loss | 57% | ~43% |
| Mean waist circumference change | −18.4 cm | ~−16 cm |
| Mean absolute weight loss | ~21.8 kg | ~23.5 kg* |
SURMOUNT-5: The Head-to-Head Trial (2025) — An Important Caveat: SURMOUNT-5 compared Mounjaro against semaglutide 2.4 mg — not the newer 7.2 mg dose. Mounjaro achieved approximately 20.2% versus 13.7% for semaglutide 2.4 mg — approximately 47% more weight loss. Based on STEP UP data (~19–21% with 7.2 mg), the margin between Mounjaro and Wegovy 7.2 mg is expected to be considerably narrower. A direct head-to-head trial against 7.2 mg has not yet been published.
Side Effects
Side Effects: Mounjaro vs Wegovy
Both treatments share a broadly similar gastrointestinal side effect profile, reflecting their shared GLP-1 receptor agonism. Differences in the frequency and intensity of specific side effects are clinically modest rather than dramatic.
Why Mounjaro's GI Side Effect Profile May Be Slightly Favourable
Several analyses suggest that Mounjaro's GIP co-agonism may partially counteract some of the GI side effects of pure GLP-1 agonism — potentially explaining why, despite greater appetite suppression and weight loss, Mounjaro's nausea and diarrhoea rates are similar to or slightly lower than Wegovy's in comparative data. This is not fully understood mechanistically but is a consistently observed pattern in clinical evidence.
Dose Escalation and Tolerability
Wegovy's escalation schedule (0.25 mg to 2.4 mg over 16 weeks, with the option to escalate further to 7.2 mg after a minimum of 4 weeks on 2.4 mg) involves more steps than Mounjaro's six-step schedule (2.5 mg to 15 mg over 20 weeks) when the 7.2 mg target dose is used. The additional dose steps for Wegovy 7.2 mg allow further adaptation time, though patients should be counselled that GI symptoms may recur briefly upon escalation beyond 2.4 mg.
| Side Effect | Mounjaro | Wegovy | Notes |
|---|---|---|---|
| Nausea | ~40% | ~44% | Broadly similar; GIP co-agonism may slightly reduce nausea vs pure GLP-1 |
| Diarrhoea | ~23% | ~30% | Mounjaro slightly lower in trial data |
| Vomiting | ~20% | ~24% | Similar across both treatments |
| Constipation | ~17% | ~24% | Mounjaro notably lower |
| Abdominal pain | ~14% | ~20% | Mounjaro lower; GIP effect may contribute |
| Pancreatitis (rare) | Similar risk | Similar risk | Both require clinical screening for risk factors |
| Gallbladder disease | Slightly elevated | Slightly elevated | Both associated with rapid weight loss |
| Thyroid (precaution) | Contraindicated in MTC/MEN2 | Contraindicated in MTC/MEN2 | Same contraindication for both |
| Injection site | Common | Common | Rotation of sites reduces frequency for both |
New in 2025/26
Oral Semaglutide Tablets (up to 25 mg): The New Wegovy Option
A significant development in the Wegovy landscape in 2025/26 is the arrival of high-dose oral semaglutide as a weight management option. This is distinct from the existing Rybelsus (oral semaglutide 14 mg for type 2 diabetes) and represents a new formulation designed specifically for weight loss.
New in 2025/26
Oral Semaglutide for Weight Loss — Wegovy Tablets, up to 25 mg
Novo Nordisk received approval for an oral semaglutide tablet for weight management in 2025. The once-daily oral tablet — distinct from Rybelsus — starts at 1.5 mg and escalates every 30 days up to a maximum maintenance dose of 25 mg. In the OASIS 1 trial (which used a 50 mg dose), weight loss of approximately 13.6% was observed at 68 weeks; the approved 25 mg formulation is expected to produce somewhat less. This is meaningfully lower than injectable Wegovy 7.2 mg (~19–21%). Mounjaro still significantly outperforms oral semaglutide on weight loss efficacy. Not yet available through all UK pharmacies — expanding in 2026. Happy Pharmacy is monitoring availability and will update its product range as supply is established.
Key Points for Patients Considering Oral Semaglutide
- Efficacy is notably lower than injectable Wegovy 7.2 mg; the approved 25 mg tablet is expected to produce less weight loss than the 50 mg dose tested in OASIS 1 (~13.6%), which itself was well below injectable 7.2 mg (~19–21%)
- No weekly injection required — a significant advantage for needle-averse patients
- Must be taken on an empty stomach with plain water only; timing requirements are strict
- Not yet available through all UK pharmacies — availability is expanding in 2026
- Mounjaro still significantly outperforms oral semaglutide on weight loss efficacy
- For patients prioritising convenience over maximum efficacy, oral semaglutide is a clinically relevant option
| Factor | Oral Semaglutide (up to 25 mg) | Injectable Wegovy 7.2 mg |
|---|---|---|
| Route | Once-daily oral tablet | Once-weekly subcutaneous injection |
| Efficacy | ~13.6% (OASIS 1, 50 mg dose, 68 wks); approved 25 mg expected to produce less | ~19–21% (STEP UP, 72 wks) |
| Dosing complexity | Daily; must be taken fasting with plain water; starts 1.5 mg, escalates every 30 days to 25 mg max | Weekly; flexible timing |
| Tolerability | Broadly similar GI profile; absorption variability | Established GI profile with dose escalation |
| Patient preference | Preferred by needle-averse patients | Preferred by those wanting weekly rather than daily dosing |
| vs Mounjaro | Significantly lower weight loss | Slightly lower weight loss than Mounjaro 15 mg |
Dosing & Convenience
Dosing and Convenience: Which Is Easier?
Injection vs Oral
Both injectable Mounjaro and injectable Wegovy involve a once-weekly subcutaneous injection using a pre-filled auto-injector pen. Technique is similar: the pen is pressed against the skin (abdomen, thigh or upper arm) and the dose is delivered automatically. Neither requires manual drawing or needle manipulation. The arrival of oral semaglutide tablets (up to 25 mg once daily) in 2025/26 gives needle-averse patients a non-injection alternative within the Wegovy product range — though efficacy at the approved 25 mg dose is expected to be lower than the injectable form.
Injection Frequency and Schedule
Both treatments require once-weekly injection on the same day each week. Mounjaro has a shorter half-life (approximately five days) compared with Wegovy (approximately seven days), which means missed doses affect blood concentration more quickly with Mounjaro than Wegovy. Consistent weekly dosing is important for both, but patients with irregular schedules may find Wegovy's longer half-life marginally more forgiving of occasional late injections.
Storage
Both Mounjaro and Wegovy require refrigeration before use between 2°C and 8°C and must not be frozen. Once removed from the refrigerator, Mounjaro pens can be stored at room temperature (up to 30°C) for up to 30 days; Wegovy pens for up to 6 weeks. Happy Pharmacy dispatches both treatments in validated cold-chain packaging.
Cost Comparison
Cost Comparison: Mounjaro vs Wegovy 2026
Despite producing greater weight loss, Mounjaro is generally priced slightly below Wegovy at equivalent dose steps in the UK market. The total first-year cost is broadly comparable, with Mounjaro's longer escalation schedule distributing costs more gradually before reaching a lower maintenance price.
| Month | Mounjaro Dose | Mounjaro Cost | Wegovy Dose | Wegovy Cost |
|---|---|---|---|---|
| Month 1 | 2.5 mg | ~£133 | 0.25 mg | ~£149 |
| Month 2 | 5 mg | ~£157 | 0.5 mg | ~£149 |
| Month 3 | 7.5 mg | ~£213 | 1.0 mg | ~£219 |
| Month 4 | 10 mg | ~£242 | 1.7 mg | ~£249 |
| Month 5 | 12.5 mg | ~£256 | 2.4 mg | ~£249 |
| Month 6+ | 15 mg | ~£285 | 7.2 mg | ~£299 |
| Year 1 total | — | ~£2,900–£3,200 | — | ~£3,100–£3,400 |
Value Consideration: When assessed by cost per percentage point of weight loss, Mounjaro and Wegovy 7.2 mg are closely matched. At approximately £285/month for ~22.5% average loss (Mounjaro) versus approximately £299/month for ~19–21% average loss (Wegovy 7.2 mg), Mounjaro continues to offer a modest cost-efficacy advantage for most patients — but the gap is considerably narrower than when compared with the earlier 2.4 mg Wegovy formulation.
Decision Guide
Mounjaro or Wegovy: Which Is Right for You?
The right treatment depends on individual clinical circumstances, priorities and lifestyle. The table below provides a practical framework.
| Choose Mounjaro if... | Choose Wegovy if... |
|---|---|
| You want maximum weight loss efficacy | You prefer a treatment with a longer UK real-world prescribing track record |
| You have significant insulin resistance or type 2 diabetes | You respond well to GLP-1 agonism and have achieved good results |
| You have not achieved your goal on Wegovy | You are currently stable and tolerating semaglutide well |
| You are managing menopausal metabolic changes | You prefer a slightly simpler escalation schedule (4 steps vs 6) |
| Larger visceral fat reduction is a clinical priority | You are interested in the oral tablet formulation (up to 25 mg once daily) |
| You want the most efficacious licensed injectable treatment | Lower per-month maintenance cost is a priority (~£299 vs ~£285) |
A Note on Switching: Patients who have started on Wegovy and not achieved their target weight loss can switch to Mounjaro with clinical guidance. Patients stable on Wegovy who are managing well may have less clinical reason to switch unless efficacy plateaus or their metabolic profile changes. Both treatments are available at Happy Pharmacy, and our prescribing team can discuss which is most appropriate for your individual circumstances.
Key Questions
Key Questions Answered
Is Mounjaro better than Wegovy?
For most patients seeking maximum weight loss, yes — though the margin is considerably narrower with Wegovy 7.2 mg. SURMOUNT-5 (2025) compared Mounjaro against semaglutide 2.4 mg and demonstrated approximately 47% greater weight loss with Mounjaro; however, Wegovy 7.2 mg (STEP UP) achieves approximately 19–21% weight loss versus Mounjaro's approximately 22.5%, a much smaller gap. Mounjaro also produces greater reductions in insulin resistance and cardiometabolic risk markers. For patients for whom needle avoidance is important, Wegovy now has a once-daily oral tablet (up to 25 mg) that Mounjaro does not. For patients stable on Wegovy 2.4 mg with good results, escalating to 7.2 mg may be a worthwhile step before switching to Mounjaro.
Which causes more weight loss — Mounjaro or Wegovy?
Mounjaro produces more weight loss than Wegovy, though the difference has narrowed with the 7.2 mg Wegovy formulation. In their respective landmark trials, Mounjaro 15 mg achieved approximately 22.5% average weight loss at 72 weeks (SURMOUNT-1) versus approximately 19–21% with Wegovy 7.2 mg at 72 weeks (STEP UP). SURMOUNT-5 compared Mounjaro against semaglutide 2.4 mg and showed approximately 47% greater weight loss with Mounjaro under those conditions; the margin against the 7.2 mg dose is expected to be substantially smaller. Mounjaro's GIP receptor co-agonism, in addition to GLP-1 agonism, is responsible for its continued efficacy advantage.
What are the main differences between Mounjaro and Wegovy?
The principal differences are: mechanism (Mounjaro activates both GLP-1 and GIP receptors; Wegovy activates GLP-1 only); efficacy (Mounjaro ~22.5% vs Wegovy 7.2 mg ~19–21% average weight loss); dose schedule (Mounjaro 6 steps over 20 weeks; Wegovy escalates to 2.4 mg over 16 weeks, then to 7.2 mg after a minimum of 4 further weeks); half-life (Mounjaro ~5 days; Wegovy ~7 days); formulations (Mounjaro injection only; Wegovy injection or new oral tablet up to 25 mg); maintenance price (Mounjaro ~£285/month; Wegovy 7.2 mg ~£299/month); UK approval timing (Mounjaro 2023; Wegovy 2.4 mg 2021, 7.2 mg 2025); and real-world track record (Wegovy has a longer prescribing history in the UK).
FAQs
Frequently Asked Questions: Mounjaro vs Wegovy
Mounjaro produces more weight loss than Wegovy, though the difference has narrowed significantly with the 7.2 mg Wegovy formulation. In their respective landmark trials, Mounjaro 15 mg achieved approximately 22.5% average weight loss at 72 weeks (SURMOUNT-1) versus approximately 19–21% with Wegovy 7.2 mg at 72 weeks (STEP UP). SURMOUNT-5 compared Mounjaro against semaglutide 2.4 mg (not 7.2 mg) and showed approximately 47% greater weight loss with Mounjaro under those conditions; the margin against the 7.2 mg dose is expected to be substantially smaller.
Oral semaglutide tablets received approval for weight management in 2025 and are expanding in availability through 2026. The once-daily oral tablet starts at 1.5 mg and escalates to a maximum of 25 mg. Efficacy at the approved 25 mg dose is expected to be lower than injectable Wegovy 7.2 mg (which achieves ~19–21%). Happy Pharmacy is monitoring availability and will update its range accordingly.
At current 2026 UK market rates, Mounjaro's maintenance dose (15 mg) costs approximately £285/month versus approximately £299/month for Wegovy's 7.2 mg maintenance dose — making Mounjaro around £14/month cheaper at maintenance. Combined with modestly higher average weight loss, Mounjaro continues to offer better cost-efficacy for most patients, though the advantage is narrower than with the previous 2.4 mg Wegovy formulation.
Yes. Switching from Wegovy to Mounjaro is a recognised clinical pathway, particularly for patients who have not achieved their target weight or who want the additional metabolic benefits of GIP receptor co-agonism. Your Happy Pharmacy prescribing team can advise on the appropriate starting dose for Mounjaro after Wegovy, taking into account your current dose and treatment history.
SURMOUNT-5 was the first randomised head-to-head trial of tirzepatide versus semaglutide, comparing Mounjaro against semaglutide 2.4 mg — not the newer 7.2 mg dose. Mounjaro achieved approximately 20.2% versus 13.7% weight loss. Based on STEP UP data (~19–21% weight loss with 7.2 mg), the gap is expected to be considerably narrower than SURMOUNT-5 suggests. A direct head-to-head trial against 7.2 mg has not yet been published.
Both share a broadly similar gastrointestinal side effect profile — nausea, diarrhoea, vomiting, constipation and abdominal pain are common with both. Mounjaro's rates are slightly lower than Wegovy's for several GI side effects, possibly because GIP receptor co-agonism partially counteracts GLP-1-driven GI effects. Both carry the same serious side effect risks (pancreatitis, gallbladder disease, thyroid contraindication).
Mounjaro. Its GIP receptor component provides insulin sensitisation beyond what GLP-1 agonism alone achieves. For patients with type 2 diabetes, PCOS or menopausal insulin resistance, Mounjaro's additional GIP mechanism directly addresses a key driver of their metabolic challenge that Wegovy does not fully reach.
Both are available through NHS specialist tier 3/4 weight management services, subject to similar eligibility criteria. Waiting times are significant in most areas. NHS Scotland does not currently fund Mounjaro on its national formulary, though Wegovy is available through specialist services. For most patients, private prescribing through a GPhC-registered pharmacy remains the practical route in 2026.
Wegovy received MHRA approval in September 2021 and has been in wider clinical use in the UK since 2022/23. Mounjaro received MHRA approval for weight management in November 2023, with NICE recommending it in 2024. Wegovy therefore has a longer real-world prescribing track record, which gives some clinicians greater familiarity with individual patient response patterns.
Both are effective starting treatments. For patients without strong preference, Mounjaro's superior efficacy makes it the stronger starting choice if maximum weight loss is the primary goal. For patients who are needle-averse, Wegovy's oral formulation option is a relevant differentiator. For patients with significant insulin resistance or metabolic syndrome, Mounjaro's dual mechanism provides a clinical advantage from the start. Happy Pharmacy's prescribing team can discuss which is most appropriate for your individual circumstances.
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Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205–216. | Once-weekly semaglutide 7.2 mg in adults with obesity (STEP UP). Lancet Diabetes Endocrinol. 2025;S2213–8587(25):00226–8. | Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). N Engl J Med. 2025. | Oral semaglutide 50 mg taken once per day in adults with overweight or obesity (OASIS 1). Lancet. 2023;402(10403):705–719. [Note: OASIS 1 tested 50 mg; approved weight management dose is 25 mg.] | Novo Nordisk. Wegovy oral semaglutide tablets (25 mg): prescribing information and regulatory submissions. 2025. | NICE TA1026. Tirzepatide for managing overweight and obesity. 2024. | NICE TA875. Semaglutide for managing overweight and obesity. 2023. | MHRA. Prescribing information for Mounjaro and Wegovy. 2023. | GPhC. Standards for registered pharmacies. 2023. gphc.org.uk | Happy Pharmacy (GPhC No. 9012585). Educational purposes only — not a substitute for individualised clinical assessment.