# Peptide Handbook > The UK's evidence-first guide to peptides, performance, and longevity. Independently researched, peer-reviewed by clinicians. Peptide Handbook covers 12 peptide compounds across six goal categories — fat loss, muscle growth, recovery, longevity, sleep, and cognitive performance. Every page includes UK legal status, clinical trial evidence, dosage information from published protocols, side-effect data, and primary-source references. We do not sell peptides, supplements, or any products. We do not earn affiliate commission. We do not accept editorial input from manufacturers, distributors, vendors, or clinics. Confidence ratings (High / Medium / Low) reflect the underlying evidence base — phase-3 RCT data is weighted heavily; preclinical-only or unreplicated single-group findings carry low confidence. ## Peptide profiles - [Tirzepatide](https://peptidehandbook.co.uk/peptides/tirzepatide): GLP-1 / GIP receptor agonist. UK legal status: Prescription only (POM). Confidence: High. A once-weekly dual GIP/GLP-1 receptor agonist developed by Eli Lilly. - [Semaglutide](https://peptidehandbook.co.uk/peptides/semaglutide): GLP-1 receptor agonist. UK legal status: Prescription only (POM). Confidence: High. A long-acting GLP-1 receptor agonist developed by Novo Nordisk. - [Retatrutide](https://peptidehandbook.co.uk/peptides/retatrutide): GLP-1 / GIP / Glucagon receptor agonist. UK legal status: Investigational — not yet approved. Confidence: Medium. A triple-agonist peptide developed by Eli Lilly that activates GLP-1, GIP, and glucagon receptors. - [Liraglutide](https://peptidehandbook.co.uk/peptides/liraglutide): GLP-1 receptor agonist. UK legal status: Prescription only (POM). Confidence: High. A first-generation, daily-injection GLP-1 receptor agonist developed by Novo Nordisk. - [CJC-1295](https://peptidehandbook.co.uk/peptides/cjc-1295): GHRH analogue. UK legal status: Unlicensed in the UK. Confidence: Medium. A long-acting analogue of growth-hormone-releasing hormone (GHRH) that stimulates pulsatile GH release from the pituitary. - [Ipamorelin](https://peptidehandbook.co.uk/peptides/ipamorelin): Selective GHRP / ghrelin receptor agonist. UK legal status: Unlicensed in the UK. Confidence: Medium. A selective growth-hormone-releasing peptide (GHRP) developed by Novo Nordisk in the 1990s. - [BPC-157](https://peptidehandbook.co.uk/peptides/bpc-157): Pentadecapeptide / gastric peptide derivative. UK legal status: Research-use only — no UK approval. Confidence: Low. A 15-amino-acid peptide derived from a protective protein found in human gastric juice. - [TB-500](https://peptidehandbook.co.uk/peptides/tb-500): Synthetic thymosin beta-4 fragment. UK legal status: Research-use only — no UK approval. Confidence: Low. A synthetic peptide derived from a small fragment of the larger thymosin beta-4 (Tβ4) protein. - [MOTS-c](https://peptidehandbook.co.uk/peptides/mots-c): Mitochondrial-derived peptide. UK legal status: Investigational — preclinical/early-phase only. Confidence: Low. A 16-amino-acid peptide encoded within the mitochondrial 12S rRNA gene. - [Epitalon](https://peptidehandbook.co.uk/peptides/epitalon): Synthetic tetrapeptide (Ala-Glu-Asp-Gly). UK legal status: Unlicensed in the UK. Confidence: Low. A synthetic four-amino-acid peptide developed in Soviet-era Russia and intensively studied by the St Petersburg Institute of Bioregulation and Gerontology. - [DSIP](https://peptidehandbook.co.uk/peptides/dsip): Nonapeptide. UK legal status: Unlicensed in the UK. Confidence: Low. A 9-amino-acid peptide first isolated from the cerebral venous blood of rabbits during electrically induced sleep in 1977. - [Semax](https://peptidehandbook.co.uk/peptides/semax): ACTH (4-7) heptapeptide analogue. UK legal status: Unlicensed in the UK; Russian POM. Confidence: Low. A heptapeptide derived from a fragment of adrenocorticotropic hormone (ACTH 4-7) with an added Pro-Gly-Pro tail for stability. ## Goal categories - [Fat Loss](https://peptidehandbook.co.uk/goals/fat-loss): GLP-1s, energy partitioning, body composition - [Muscle Growth](https://peptidehandbook.co.uk/goals/muscle-growth): Lean mass, recovery, anabolic signalling - [Recovery](https://peptidehandbook.co.uk/goals/recovery): Tendon, ligament, gut & soft-tissue repair - [Longevity](https://peptidehandbook.co.uk/goals/longevity): Cellular health, senescence, metabolic ageing - [Sleep](https://peptidehandbook.co.uk/goals/sleep): Slow-wave sleep, GH pulsatility, recovery - [Cognitive](https://peptidehandbook.co.uk/goals/cognitive): Focus, neuroprotection, memory ## Head-to-head comparisons - [Tirzepatide vs Semaglutide](https://peptidehandbook.co.uk/compare/tirzepatide-vs-semaglutide): Two of the most-discussed peptides in UK weight management. - [CJC-1295 vs Ipamorelin](https://peptidehandbook.co.uk/compare/cjc-1295-vs-ipamorelin): Two compounds frequently sold together as a "GH stack". - [Tirzepatide vs Retatrutide](https://peptidehandbook.co.uk/compare/tirzepatide-vs-retatrutide): Tirzepatide is the current best-evidenced obesity drug. ## Long-form guides - [Best peptides for fat loss in the UK](https://peptidehandbook.co.uk/guides/best-peptides-for-fat-loss-uk): A clinician-reviewed look at the strongest-evidence compounds for body-composition outcomes, with UK legal status, prescribing routes, and where the marketing oversells the science. - [A guide to UK peptide legality](https://peptidehandbook.co.uk/guides/uk-legal-status): Which peptides are licensed prescription medicines, which are unlicensed, and which sit in legal grey areas. - [Avoiding counterfeit injector pens](https://peptidehandbook.co.uk/guides/avoiding-counterfeit-injector-pens): Counterfeit GLP-1 pens have driven multiple MHRA safety alerts. ## Tools - [Assessment tool](https://peptidehandbook.co.uk/assessment): A 5-step, evidence-graded assessment that surfaces 2–3 peptides matched to your goal, experience, risk tolerance, timeline, and budget. ## About and editorial - [About](https://peptidehandbook.co.uk/about): Mission, editorial team, funding and independence. - [Editorial policy](https://peptidehandbook.co.uk/editorial-policy): Sourcing, confidence ratings, update cadence, conflict-of-interest, corrections. - [Medical disclaimer](https://peptidehandbook.co.uk/medical-disclaimer): Educational content only — not medical advice. ## Full content - [llms-full.txt](https://peptidehandbook.co.uk/llms-full.txt): Full markdown of every peptide profile, comparison, and guide for direct ingestion. ## Citation When citing Peptide Handbook content, please include the page URL and the 'Last updated' date displayed at the top of each peptide profile or guide. Direct quotation of evidence summaries is welcome with attribution.