Retatrutide vs Tirzepatide: Which Is Right for You?

Both are incretin-mimetic peptides. Tirzepatide hits two receptors (GLP-1, GIP); retatrutide hits three (GLP-1, GIP, glucagon). That third receptor is what makes retatrutide so much stronger per milligram — and why it sits at the cutting edge of UK obesity research.

Mechanism

Tirzepatide — dual agonist. Slows gastric emptying, suppresses appetite, improves insulin sensitivity.

Retatrutide — triple agonist. All of the above plus glucagon-driven thermogenesis and lipolysis.

Published results

Outcome	Tirzepatide	Retatrutide
Weight loss at 48 weeks (max dose)	~21%	~24%
Active receptors	2	3
Trial maturity	Phase 3 complete	Phase 2 complete; Phase 3 ongoing

Side-effect profile

Both share the GI side-effect curve (nausea, slow gut) at higher doses. Retatrutide adds mild elevated heart rate in some subjects due to the glucagon component.

Cost in the UK

Retatrutide is currently more expensive per mg, but the per-effective-dose cost is similar because doses are lower.

Which should you pick?

Want proven, predictable results? Tirzepatide.
Want the strongest available effect and don't mind being on the research edge? Retatrutide.

Frequently asked questions

Is retatrutide approved by the MHRA?

No. Both are peptides only in the UK. Phase-3 trials are ongoing for retatrutide.

Can I run both together?

Stacking incretin mimetics is not supported by published data. Pick one.

Which has fewer side effects?

Tirzepatide, marginally — retatrutide's glucagon component adds mild cardiovascular changes.

Where can I buy both?

Both stocked at Next Day Pharma: tirzepatide and retatrutide.

This guide is provided for informational purposes by Next Day Pharma. All peptides supplied are FOR RECONSTITUTION. Always consult a qualified healthcare professional before use.

Peptide catalogue

Melanotan II — £40.00 — 10mg of Melanotan II
Somatropin (HGH) — £60.00 — Somatropin (Human Growth Hormone)
Cagrilintide 10mg — £60.00 — 10mg of Cagrilintide
Epitathlon — £50.00 — 10mg of Epitathlon
PT-141 10mg — £40.00 — 10mg of PT-141
SLU-332 5mg — £65.00 — 5mg of SLU-332
CJC + Ipamorelin — £55.00 — 5mg CJC-1295 + 5mg Ipamorelin
5 Amino 1MQ 50mg — £60.00 — 50mg of 5 Amino 1MQ
SS-31 10mg — £40.00 — 10mg of SS-31
Semax 10mg — £40.00 — 10mg of Semax
Selank 10mg — £40.00 — 10mg of Selank
Ipamorelin 10mg — £40.00 — 10mg of Ipamorelin
Wolverine — £75.00 — 10mg of Wolverine
MOTS-C 20mg — £80.00 — 20mg of MOTS-C
Tesamorelin 20mg — £110.00 — 20mg of Tesamorelin
NAD+ 1000mg — £125.00 — 1000mg of NAD+
GLO 70mg — £70.00 — 70mg of GLO
KLOW 80mg — £90.00 — 80mg of KLOW
BPC-157 10mg — £40.00 — 10mg of BPC-157
TB500 10mg — £50.00 — 10mg of TB500
Retatrutide — £200.00 — Retatrutide
Tirzepatide — £180.00 — Tirzepatide
MT2 10mg (NEXT DAY TAN) — £50.00 — 10mg of Melanotan2
GHK-CU 100mg — £60.00 — 100mg of GHK-CU

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Peptide buying guides

Peptide pens vs vials — Accuracy, cost, sterility and storage compared - and why we supply pens only.
How much does Tirzepatide cost in the UK? — Cost per week by strength, how clinic pricing compares, and how to lower the total.
Retatrutide results week by week — What users commonly report from week one through maintenance.
Best peptides for fat loss in the UK — Retatrutide, Tirzepatide, Cagrilintide and 5-Amino-1MQ compared by mechanism.
Are peptides legal in the UK? — Possession, supply rules, customs and what to check before ordering.
Tirzepatide side effects — What appears when, how long it lasts and what actually helps.
Retatrutide side effects — Why titration speed matters most, and how to manage the first days after a dose.
Where to buy Retatrutide in the UK — Supplier checklist, real pricing, pens vs powder, dosing and next-day tracked delivery.
Where to buy Tirzepatide in the UK — What to check in a UK supplier, how pens compare on cost, and the standard titration schedule.
Where to buy Melanotan 2 in the UK — Buying MT2 safely in the UK, loading vs maintenance dosing, and what to expect week by week.
Where to buy PT-141 in the UK — PT-141 (Bremelanotide) explained: UK supply, timing, typical doses and common questions.
Tirzepatide vs Retatrutide — Dual vs triple agonist compared on strength, dosing, side effects and cost.
Tirzepatide vs Semaglutide — How the dual agonist compares with the original GLP-1 on results, tolerability and dosing.
BPC-157 dosage guide — Typical daily amounts, timing and cycle length for BPC-157.
Where to buy Cagrilintide in the UK — The amylin analogue explained: how it differs from GLP-1s, weekly amounts and UK supply.
Where to buy NAD+ in the UK — Injectable vs oral, typical amounts, why people flush and how to avoid it.
Where to buy GHK-Cu in the UK — Copper peptide for skin, hair and recovery: amounts, cycling and storage.
Where to buy TB-500 in the UK — Loading and maintenance amounts, and how TB-500 compares with BPC-157.
Where to buy 5-Amino-1MQ in the UK — Fat loss without appetite suppression: how NNMT inhibition differs from GLP-1s.
How to use a pre-filled peptide pen — Step by step for a first dose: dialling, sites, the ten-second hold and sharps disposal.
What to do if you miss a dose — How late is too late, when to skip, and coming back after a break.
Travelling with peptide pens — Airport security, cool bags, hotel fridges and how long pens last out of the fridge.
How to store peptide pens in the UK — Fridge temperatures, in-use windows, travelling and what to do after a delivery delay.
Free peptide dosage calculator — Work out doses and volumes for the most common peptides.
Dosage and titration guide — Find the pen strength that matches your weekly dose.