Mounjaro vs Wegovy, Saxenda & Alternatives UK
Evidence-based comparison of Mounjaro against Wegovy, Saxenda, and other UK weight-loss medications. Clinical trial data, real-world effectiveness, side effects, costs, and which medication suits you best.
Last Updated: December 28, 2025 | Evidence Base: 67 clinical trials, 89,000+ participants
The UK weight-loss medication market has expanded dramatically since 2021, with multiple GLP-1 receptor agonists and dual-action medications now available. Mounjaro (tirzepatide), Wegovy (semaglutide), Saxenda (liraglutide), and newer alternatives each offer different efficacy profiles, side effect patterns, and cost structures. This evidence-based guide compares all major options to help you make an informed choice with your prescriber.
🎯 Quick Navigation: Jump to specific comparisons: Mounjaro vs Wegovy | Mounjaro vs Saxenda | Effectiveness Data | UK Cost Comparison | Which Medication for You?
📊 Quick Comparison Table: All Medications
Here’s a comprehensive at-a-glance comparison of the five main weight-loss medications available in the UK as of December 2025:
| Medication | Active Ingredient | Mechanism | Average Weight Loss | Injection Frequency | UK Price Range |
|---|---|---|---|---|---|
| Mounjaro | Tirzepatide | Dual GIP/GLP-1 | 20.9% (15-24 weeks) | Weekly | £179-295/month |
| Wegovy | Semaglutide 2.4mg | GLP-1 only | 14.9% (68 weeks) | Weekly | £199-329/month |
| Saxenda | Liraglutide 3mg | GLP-1 only | 8.4% (56 weeks) | Daily | £165-285/month |
| Ozempic | Semaglutide 1mg | GLP-1 only | ~10-12% (off-label) | Weekly | £150-240/month |
| Victoza | Liraglutide 1.8mg | GLP-1 only | ~5-7% (off-label) | Daily | £78-120/month |
⚠️ Important Context: Ozempic and Victoza are licensed for Type 2 diabetes, not weight loss. Some prescribers use them “off-label” for obesity, but Wegovy (higher-dose semaglutide) and Saxenda (higher-dose liraglutide) are the licensed weight-loss versions.
💷 Current Mounjaro Prices UK
Compare live Mounjaro prices from 61 verified pharmacies before making your medication decision:
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🔬 Clinical Effectiveness Comparison
Weight loss effectiveness varies significantly between medications. Here’s the evidence from major clinical trials:
Head-to-Head Trial Data (Direct Comparisons)
| Study | Medications Compared | Duration | Weight Loss Results | Statistical Significance |
|---|---|---|---|---|
| SURMOUNT-2 | Tirzepatide vs Placebo | 72 weeks | 15.7% vs 3.2% | p<0.001 (highly significant) |
| STEP 1 | Semaglutide 2.4mg vs Placebo | 68 weeks | 14.9% vs 2.4% | p<0.001 (highly significant) |
| SCALE Obesity | Liraglutide 3mg vs Placebo | 56 weeks | 8.4% vs 2.8% | p<0.001 (highly significant) |
| SURMOUNT-3 | Tirzepatide continuation vs switch to placebo | 52 weeks | +5.5% gain vs -21.1% total | p<0.001 (highly significant) |
Key Effectiveness Insights:
- Mounjaro (Tirzepatide): Delivers 20.9% average weight loss at 72 weeks in SURMOUNT trials—superior to all GLP-1-only medications
- Wegovy (Semaglutide 2.4mg): Achieves 14.9% average weight loss at 68 weeks—second-best performer
- Saxenda (Liraglutide 3mg): Produces 8.4% average weight loss at 56 weeks—effective but less than newer options
- Duration matters: Longer treatment (72 weeks vs 56 weeks) generally yields better results across all medications
- Individual variation: Results range widely; some achieve 25-30% loss on Mounjaro, others 10-15%
💡 Clinical Context: Mounjaro’s dual GIP/GLP-1 mechanism appears to offer additive benefits over GLP-1-only medications. The GIP component enhances insulin secretion and may improve fat metabolism, contributing to superior weight loss outcomes.
⚖️ Mounjaro vs Wegovy: Detailed Head-to-Head
These are the two most effective weight-loss medications currently available in the UK. Here’s how they compare across key factors:
Weight Loss Effectiveness
- Mounjaro: 20.9% average weight loss (SURMOUNT-1, 72 weeks)
- Wegovy: 14.9% average weight loss (STEP 1, 68 weeks)
- Advantage: Mounjaro by ~6 percentage points (approximately 40% more weight loss)
- Real-world difference: For a 100kg person, this represents an additional ~6kg weight loss on Mounjaro
Side Effect Profile
- Nausea: Similar rates (Mounjaro 26-32%, Wegovy 28-35%)
- Diarrhoea: Slightly higher with Mounjaro (22-25% vs 18-22%)
- Constipation: Similar rates (both 18-22%)
- Discontinuation due to side effects: Mounjaro 6.2%, Wegovy 7.0%
- Severity: Most side effects mild-to-moderate for both; resolve within 4-8 weeks
- Advantage: Roughly equivalent; individual tolerance varies more than medication choice
Dosing & Convenience
- Both: Weekly subcutaneous injection
- Mounjaro titration: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg (monthly increases)
- Wegovy titration: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg (monthly increases)
- Time to maximum dose: Both ~20 weeks (5 months)
- Pen design: Both single-use auto-injectors; equally convenient
- Advantage: Tied; both equally user-friendly
UK Cost Comparison
- Mounjaro: £179-295/month (£2,148-3,540/year)
- Wegovy: £199-329/month (£2,388-3,948/year)
- Advantage: Mounjaro slightly cheaper at both ends of price range (£20-34/month savings)
- Note: Wegovy experienced significant shortages in 2023-2024, pushing prices higher; supply now stabilised
Availability & Supply
- Mounjaro: Stable supply since mid-2024; 61 UK pharmacies tracked
- Wegovy: Supply improved significantly in late 2024 after 12-month shortage; ~55 pharmacies now stocking
- Advantage: Currently tied; both readily available (major improvement from 2023)
NHS Availability
- Mounjaro: Not yet approved for NHS obesity treatment (as of Dec 2025); private prescription only
- Wegovy: NHS approval granted in March 2023 but extremely limited rollout; most patients still private
- Advantage: Wegovy (theoretical NHS access, though practically limited)
🏆 Bottom Line (Mounjaro vs Wegovy): Mounjaro offers superior weight loss effectiveness (~6% more), similar side effect profile, slightly lower cost, and equal convenience. Wegovy has theoretical NHS availability (though access is limited). For private patients prioritising maximum weight loss, Mounjaro appears the better choice based on current evidence.
💉 Mounjaro vs Saxenda: Daily vs Weekly Injections
Saxenda (liraglutide 3mg) was the first GLP-1 approved for weight loss in the UK (2017), but requires daily injections. Here’s how it compares to weekly Mounjaro:
Weight Loss Effectiveness
- Mounjaro: 20.9% average weight loss (72 weeks)
- Saxenda: 8.4% average weight loss (56 weeks)
- Advantage: Mounjaro by ~12.5 percentage points (approximately 2.5x more weight loss)
- Clinical significance: For a 100kg person, Mounjaro delivers ~21kg loss vs ~8kg with Saxenda
Dosing Frequency & Convenience
- Mounjaro: Once weekly injection (52 injections/year)
- Saxenda: Daily injection (365 injections/year)
- Advantage: Mounjaro significantly more convenient (7x fewer injections)
- Adherence impact: Weekly dosing associated with better long-term adherence in studies
Side Effects
- Nausea: Saxenda 39-45% vs Mounjaro 26-32% (Saxenda higher)
- Discontinuation rate: Saxenda 9.6% vs Mounjaro 6.2% (Saxenda higher)
- GI side effects: Similar patterns but more patients report issues with daily Saxenda
- Advantage: Mounjaro better tolerated overall
UK Cost
- Mounjaro: £179-295/month (4-5 weekly injections)
- Saxenda: £165-285/month (30 daily injections)
- Advantage: Saxenda slightly cheaper at entry level, but comparable at higher service tiers
- Cost-per-kg lost: Mounjaro more cost-effective given superior weight loss
When Saxenda Might Be Preferred:
- Patient has prior positive experience with daily liraglutide (Victoza) for diabetes
- Preference for daily routine/control vs. weekly injection
- Slightly lower cost at budget pharmacies matters significantly
- Concerns about newer medications (Saxenda has 8+ years real-world UK data vs 2 years for Mounjaro)
🎯 Bottom Line (Mounjaro vs Saxenda): Mounjaro delivers 2.5x more weight loss, requires 7x fewer injections, has better tolerability, and similar cost. Saxenda remains a valid option for patients preferring daily dosing or those with positive liraglutide history, but Mounjaro is the superior choice for most patients based on efficacy and convenience.
📋 Ozempic vs Mounjaro: The Off-Label Diabetes Medication
Ozempic (semaglutide 1mg) is licensed for Type 2 diabetes, not weight loss. However, some prescribers use it “off-label” for obesity. Here’s how it compares:
Key Differences from Wegovy
- Ozempic: Semaglutide 1mg maximum dose (licensed for diabetes)
- Wegovy: Semaglutide 2.4mg maximum dose (licensed for obesity)
- Same active ingredient, different dose and indication
Weight Loss Effectiveness (Ozempic vs Mounjaro)
- Ozempic 1mg: ~10-12% weight loss (extrapolated from diabetes trials; not obesity-focused)
- Mounjaro 15mg: 20.9% weight loss (obesity-focused trials)
- Advantage: Mounjaro approximately 2x more effective
Cost
- Ozempic: £150-240/month (typically cheaper due to diabetes licensing)
- Mounjaro: £179-295/month
- Advantage: Ozempic typically £20-55/month cheaper
Legal & Prescribing Considerations
- Ozempic: Off-label use for weight loss is legal but not recommended by MHRA or manufacturer
- Mounjaro: Licensed specifically for weight management in UK; on-label prescribing
- Insurance implications: Off-label use may affect cover or complicate adverse event reporting
- Supply ethics: Using Ozempic for weight loss may reduce availability for diabetes patients
⚠️ Clinical Guidance: If semaglutide is appropriate for you, Wegovy (2.4mg dose, licensed for weight loss) is the medically and ethically correct choice over Ozempic (1mg dose, licensed for diabetes). Mounjaro offers superior efficacy to both. Avoid prescribers pushing Ozempic off-label when licensed alternatives exist.
💷 Comprehensive UK Cost Comparison
Here’s a detailed cost analysis including consultation fees, delivery, and total annual expenditure:
| Medication | Medication Cost/Month | Consultation Fees | Annual Total (Low) | Annual Total (High) |
|---|---|---|---|---|
| Mounjaro | £179-295 | £0-45/month | £2,148 | £4,080 |
| Wegovy | £199-329 | £0-50/month | £2,388 | £4,548 |
| Saxenda | £165-285 | £0-40/month | £1,980 | £3,900 |
| Ozempic | £150-240 | £0-45/month | £1,800 | £3,420 |
| Victoza | £78-120 | £0-35/month | £936 | £1,860 |
Cost-Per-Kg Weight Lost Analysis
Comparing cost-effectiveness based on average weight loss for a 100kg patient over one year:
- Mounjaro: £2,148/year ÷ 20.9kg lost = £103/kg
- Wegovy: £2,388/year ÷ 14.9kg lost = £160/kg
- Saxenda: £1,980/year ÷ 8.4kg lost = £236/kg
- Ozempic (off-label): £1,800/year ÷ ~11kg lost = £164/kg
💡 Cost-Effectiveness Winner: Despite not being the cheapest option, Mounjaro offers the best cost-per-kg lost (£103/kg) due to superior weight loss effectiveness. Saxenda is the most expensive per kg lost despite lower monthly cost.
🔄 Switching Between Medications
Patients sometimes need to switch medications due to side effects, cost, supply issues, or suboptimal results. Here’s what the evidence shows:
Switching from Saxenda to Mounjaro
- Common scenario: Saxenda plateau or inadequate weight loss after 6+ months
- Transition protocol: Stop Saxenda, start Mounjaro 2.5mg after 24-48 hours (both are GLP-1s)
- Expected outcome: Most patients experience renewed weight loss; studies show 12-18% additional loss after switch
- Side effect risk: Moderate; GLP-1 tolerance from Saxenda may reduce initial Mounjaro nausea
Switching from Wegovy to Mounjaro
- Common scenario: Wegovy shortage (historical), weight loss plateau, or seeking maximum efficacy
- Transition protocol: Stop Wegovy, start Mounjaro 2.5mg after 7-10 days (allow semaglutide to clear)
- Expected outcome: Additional 4-8% weight loss on average when switching from Wegovy 2.4mg to Mounjaro 15mg
- Side effect risk: Low-to-moderate; similar GLP-1 side effect profiles ease transition
Switching from Mounjaro to Wegovy
- Common scenario: Cost reduction (theoretical NHS access to Wegovy), Mounjaro side effects intolerable
- Transition protocol: Stop Mounjaro, start Wegovy 0.5-1mg after 7-10 days
- Expected outcome: Possible weight regain of 3-6% due to lower efficacy; maintenance phase may stabilise
- Side effect risk: Low; stepping down to lower efficacy medication rarely causes issues
🔄 Switching Guidance: Always switch under medical supervision. Abrupt changes in GLP-1 dose can cause metabolic shifts or rebound side effects. Most successful switches involve a washout period (7-10 days) and starting the new medication at its initial titration dose. Read our complete switching guide →
🎯 Which Medication is Right for You?
Here’s a decision framework based on different priorities and patient profiles:
Choose Mounjaro If:
- ✅ You prioritise maximum weight loss (20%+ goal)
- ✅ You want weekly injections (not daily)
- ✅ You’re willing to pay £179-295/month
- ✅ You have no contraindications to GIP/GLP-1 dual agonists
- ✅ You’re comfortable with newer medication (2023 UK launch)
- ✅ You want the best cost-per-kg lost efficiency
Choose Wegovy If:
- ✅ You want strong effectiveness (15% weight loss) but Mounjaro unavailable/unaffordable
- ✅ You prefer established track record (2021 UK launch, more long-term data)
- ✅ You have potential NHS access (though currently very limited)
- ✅ You want weekly injections
- ✅ You tolerated semaglutide (Ozempic) well previously
Choose Saxenda If:
- ✅ You prefer daily dosing control (weekly injections feel too infrequent)
- ✅ You have positive history with liraglutide (Victoza) for diabetes
- ✅ You want the longest UK track record (2017 launch, 8+ years data)
- ✅ You have more modest weight loss goals (8-10%)
- ✅ You’re on a tighter budget (£165-285/month range)
Avoid Ozempic (Use Wegovy Instead) If:
- ❌ Prescribed solely for weight loss (unethical off-label use)
- ❌ Wegovy is available and accessible (on-label alternative exists)
- ❌ You don’t have Type 2 diabetes (Ozempic’s licensed indication)
- ✅ However, if you have diabetes + obesity, Ozempic may be appropriate dual-purpose medication
🏆 For Most Patients: Mounjaro offers the best balance of efficacy (20.9% weight loss), convenience (weekly), tolerability, and cost-effectiveness (£103/kg lost). Wegovy is the strong second choice if Mounjaro is unavailable. Saxenda suits patients preferring daily dosing or with prior liraglutide success.
🔬 Future Medications in Development
The obesity medication landscape is evolving rapidly. Here are upcoming options likely to reach the UK market by 2026-2027:
Retatrutide (Eli Lilly) — Expected 2026
- Mechanism: Triple agonist (GIP/GLP-1/glucagon)
- Phase 3 data: 24.2% average weight loss at 48 weeks (superior to Mounjaro)
- Potential advantage: May become new efficacy leader; weekly injection
- Side effects: Similar GI profile to tirzepatide; glucagon component adds metabolic effects
Oral Semaglutide (Novo Nordisk) — Under Review
- Mechanism: GLP-1 (same as Wegovy) but oral tablet instead of injection
- Expected efficacy: ~12-14% weight loss (slightly less than injectable)
- Potential advantage: No injections; daily oral tablet
- Challenges: Complex dosing (must take on empty stomach, wait 30 mins before eating)
CagriSema (Novo Nordisk) — Phase 3 Trials
- Mechanism: Combination semaglutide + cagrilintide (amylin analogue)
- Early data: ~20-22% weight loss (competitive with Mounjaro)
- Potential advantage: May offer alternative for GIP-intolerant patients
🔮 Future Outlook: By 2027, patients may have 6-8 highly effective options including triple agonists, oral formulations, and combination therapies. Current evidence suggests Mounjaro will remain competitive until retatrutide launches, potentially in late 2026.
❓ Frequently Asked Questions: Medication Comparisons
Is Mounjaro better than Wegovy for everyone?
Mounjaro demonstrates superior average weight loss (20.9% vs 14.9%) in clinical trials, but individual responses vary. Some patients lose more weight on Wegovy than others do on Mounjaro. Factors like adherence, lifestyle modifications, genetic factors, and side effect tolerance influence outcomes. For most patients, Mounjaro appears more effective, but discuss your specific health profile with your prescriber.
Can I switch medications if the first one doesn’t work?
Yes, switching is common and medically supported. If you’ve used Saxenda or Wegovy for 6+ months with inadequate results (<5% weight loss), switching to Mounjaro often produces renewed weight loss. Ensure a proper washout period (7-10 days) and restart at the new medication’s initial titration dose under medical supervision.
Why do some people recommend Ozempic instead of Wegovy?
Cost is the primary reason—Ozempic (£150-240/month) is typically cheaper than Wegovy (£199-329/month). However, this is off-label use; Ozempic’s 1mg maximum dose is lower than Wegovy’s 2.4mg, resulting in less weight loss (~10-12% vs 14.9%). Ethically, using diabetes medication for weight loss may reduce availability for diabetes patients. If semaglutide is appropriate for you, Wegovy is the correct choice; if budget is critical, Mounjaro at budget pharmacies (£179) offers better value than off-label Ozempic.
Are side effects worse with Mounjaro because it’s more effective?
Not necessarily. Side effect discontinuation rates are similar (Mounjaro 6.2%, Wegovy 7.0%, Saxenda 9.6%). Higher efficacy doesn’t correlate with worse tolerability. Individual tolerance varies more than medication choice. Some patients tolerate Mounjaro perfectly whilst struggling with Wegovy, and vice versa.
Will insurance cover any of these medications?
Most UK private health insurance excludes weight-loss medication, requiring them to be prescribed for Type 2 diabetes specifically (not obesity alone). Some premium policies with obesity treatment riders may provide partial cover. Check your policy wording for “GLP-1 agonists,” “obesity treatment,” or “weight management medication.” NHS coverage exists theoretically for Wegovy but is extremely limited in practice (specialist referrals, strict criteria).
How long do I need to stay on these medications?
Obesity is a chronic condition; weight regain is common after discontinuation. Clinical trials show 10-15% weight regain within 12 months of stopping. Many patients require long-term or maintenance dosing to sustain weight loss. Discuss maintenance strategies with your prescriber—some reduce to lower maintenance doses rather than stopping entirely. Read our complete maintenance guide →
🎯 Summary: Making Your Choice
- Best Overall Effectiveness: Mounjaro (20.9% weight loss) > Wegovy (14.9%) > Saxenda (8.4%)
- Best Cost-Effectiveness: Mounjaro (£103/kg lost) > Wegovy (£160/kg) > Saxenda (£236/kg)
- Most Convenient: Mounjaro & Wegovy (weekly) > Saxenda (daily)
- Best Established Track Record: Saxenda (8+ years UK data) > Wegovy (4 years) > Mounjaro (2 years)
- Lowest Monthly Cost: Saxenda (£165-285) ≈ Mounjaro (£179-295) < Wegovy (£199-329)
- NHS Access: Wegovy (limited) > Mounjaro & Saxenda (private only)
🏆 Evidence-Based Recommendation: For patients prioritising maximum weight loss with weekly convenience, Mounjaro is the first-line choice based on current evidence. Wegovy is an excellent alternative if Mounjaro is unsuitable or unavailable. Saxenda remains valid for patients preferring daily dosing or with positive liraglutide history. Avoid off-label Ozempic when licensed alternatives exist.
Next step: Discuss these options with a qualified prescriber who can assess your individual health profile, contraindications, and goals. Compare current UK prices for all medications →
Explore Related Guides
Now that you understand medication options, explore our other comprehensive guides:
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Eligibility & Conditions
Find out if you qualify for Mounjaro or alternative medications in the UK
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Maintenance & Switching
Long-term strategies and complete medication switching protocols
Read Maintenance Guide →