Peptide guides

This hub maps every major research peptide to a dosing protocol, a comparator compound, and a use-case category. You can jump from goal to mg/week titration in two clicks. The benchmark for research-grade material in 2026 is ≥95% HPLC (high-performance liquid chromatography) purity on the COA (certificate of analysis), with premium batches advertised at 98%+ [5][6].

Purity alone does not confirm identity, sterility, or endotoxin status. HPLC measures only the target compound's concentration, not whether contaminants or bacterial endotoxins are present [5].

Key Takeaways

• Research peptides in the UK are assessed by the MHRA on presentation and function, not on "research use only" labels alone
• The 2026 dosing matrix covers 14 major compounds across five categories: recovery, growth, weight loss, longevity, and skin
• Reconstitution maths (vial strength + water volume) determines syringe reading; 2 ml bacteriostatic water per 5–10 mg vial is the standard default
• Tirzepatide and retatrutide show the strongest published weight-loss data; BPC-157 and TB-500 are the most-stacked recovery peptides
• Third-party COAs with lot traceability, sterility and endotoxin confirmation are non-negotiable for supplier diligence

What you'll learn in this guide:

• How to read a peptide dosing protocol and convert between units (mcg, mg, IU)
• The 2026 UK peptide matrix: dose ranges, reconstitution volumes, and cycle lengths for 14 major compounds
• Side-by-side comparisons of weight-loss peptides (GLP-1 class), recovery peptides, growth-hormone secretagogues, and longevity compounds
• Practical sourcing and supplier diligence checks for UK research peptides
• Answers to the most common dosing questions

What this guide covers at a glance

The MHRA (Medicines and Healthcare products Regulatory Agency) treats "not for human consumption" labelling as non-determinative. Presentation and function decide medicinal status [4]. A vial marked for research use can still fall under medicines regulation if it is marketed with dosing instructions or therapeutic claims.

The 2026 UK Peptide Protocol Matrix

Below is the single reference table that maps every major research peptide covered on this hub to its category, typical research dose range, reconstitution volume, injection frequency, cycle length, and primary endpoint. Dose ranges are anchored to the trial or protocol source where one exists. Emerging compounds without published human dosing are flagged as investigational. Reconstitution assumes bacteriostatic water and a U100 insulin syringe; recalculate if you use a different vial size [6].

The standard UK reconstitution default is 2 ml bacteriostatic water per 5–10 mg vial. This lets a U100 insulin syringe read mg directly off the unit scale [6]. For the recovery row, how to dose BPC-157 and TB-500 walks through the stack timing and injection-site logic. For the GLP-1 block, Retatrutide vs Semaglutide vs Tirzepatide is the comparator hub these three rows feed into.

How to read this table

Each dose range is the research-protocol band, not a prescribed human dose. Where a row cites a 2021–2024 trial, the titration schedule comes from that trial's published arm. Where it cites [5] or [1], the figures are vendor-protocol or preclinical and should be treated as a starting reference rather than a clinical target. MOTS-c is included for completeness but has no standardised human dose in the cited literature [1].

How to read a peptide dosing protocol

A peptide dosing protocol is a four-part instruction: vial strength (mg), reconstitution volume (ml of bacteriostatic water), per-dose amount (mcg or IU), and the unit reading on a U-100 insulin syringe [5]. Get those four numbers right and the rest is just frequency and duration.

mcg, mg, IU, what each unit means

1 mg = 1,000 mcg. IU (international units) is a biological-activity unit used mainly for somatropin and hCG (human chorionic gonadotropin). With IU, 1 mg does not equal a fixed IU value, you must read the vial's stated conversion [5]. For everything else in the matrix above, work in mg and mcg only.

Reconstitution volume sets your concentration

The vial strength does not change when you add water. The concentration does. A 5 mg vial with 2 ml bac water gives 2,500 mcg/ml. The same vial with 3 ml gives approximately 1,667 mcg/ml. More water means more units on the syringe per dose, which makes small doses easier to draw accurately but eats vial volume faster [6].

U-100 syringe maths

A U-100 insulin syringe has 100 units across 1 ml, so 1 unit = 0.01 ml. To convert a dose to units: (dose in mcg ÷ concentration in mcg/ml) × 100.

Worked example: 5 mg BPC-157, 2 ml bac water

Same vial, 3 ml of water instead: concentration drops to approximately 1,667 mcg/ml, and 250 mcg now reads as 15 units. The dose is identical; the line on the syringe is not. For the full recovery stack maths including TB-500 co-dosing, see how to dose BPC-157 and TB-500.

Weight-loss peptides compared (GLP-1 class)

Tirzepatide currently has the best published mean weight loss of any approved GLP-1-class peptide because it activates two receptors rather than one. Retatrutide leads phase 2 data with a triple-receptor mechanism. Semaglutide remains the most evidence-stacked single-agonist option. Cagrisema (cagrilintide + semaglutide) sits between them in mechanism and is still maturing on outcome data. Nausea clusters in the first two steps across all four compounds, so titration speed matters more than the final dose if you're concerned about side-effect burden.

Receptor targets diverge sharply, and that drives both the titration ladder and the side-effect profile. Semaglutide is a pure GLP-1 (glucagon-like peptide-1) agonist. Tirzepatide is a dual GIP (glucose-dependent insulinotropic polypeptide)/GLP-1 agonist. Retatrutide is a triple agonist (GIP/GLP-1/glucagon). Cagrisema pairs a long-acting amylin analogue with semaglutide, which is why its appetite-suppression curve looks different week to week.

Titration is non-optional. Nausea and GI (gastrointestinal) dropout in STEP-1 and SURMOUNT-1 both cluster in the first two dose steps, which is why the 4-week hold exists. Half-lives in the 5–7 day range mean a single missed week barely moves trough levels, but two missed weeks usually warrants stepping back one rung before resuming.

The glucagon arm on retatrutide is the reason its weight-loss curve hasn't plateaued at 48 weeks the way semaglutide's does at 60 weeks. Glucagon drives additional hepatic glucose output and lipolysis.

For the full side-by-side including injection-site rotation, cost per mg in GBP, and how the titration interacts with training volume, see Retatrutide vs Semaglutide vs Tirzepatide.

Recovery and healing peptides compared

BPC-157 and TB-500 are the two recovery peptides most often stacked in research models because they act on different repair pathways. BPC-157 drives angiogenesis and upregulates VEGFR2 (vascular endothelial growth factor receptor 2), which is why it dominates gut, tendon and ligament protocols. TB-500 (the synthetic fragment of Thymosin Beta-4) binds G-actin and accelerates cell migration, making it the go-to for muscle belly tears and systemic soft-tissue insults. Stacking both costs more than running either solo, but the synergistic effect on repair timelines is well-documented in animal models.

When to run them solo vs stacked

Solo BPC-157 makes sense for localised, vascular-poor structures: Achilles, patellar tendon, medial epicondyle, and gut lining work because these tissues have limited blood supply and benefit from the angiogenic signal. Subcutaneous injection near the injury site is the dominant research route, though systemic SC also shows effect in animal models. TB-500 solo fits diffuse or multi-site soft-tissue research, where injection-site targeting isn't practical.

The stack rationale is straightforward: TB-500's slower, systemic cell-migration effect complements BPC-157's faster local angiogenic response. The two haven't shown receptor competition in published models. Most stack protocols run 6 weeks then drop TB-500 to monthly while continuing BPC-157 daily for another fortnight. Reconstitution maths, syringe sizing in IU, and injection-site rotation are covered in the dedicated how to dose BPC-157 and TB-500 protocol page.

Growth-hormone peptides compared

The four sit on a spectrum from pulsatile stimulation to direct replacement. GHRH (growth hormone-releasing hormone) analogues (CJC-1295, Tesamorelin) prompt the pituitary to release endogenous GH. Ghrelin mimetics (Ipamorelin) amplify the pulse via a separate receptor. Recombinant HGH (Somatropin) bypasses the pituitary entirely. Stacking a GHRH with a ghrelin mimetic is the standard research design because the two pathways multiply rather than add. The no-DAC + Ipamorelin combination is the most forgiving entry point for newcomers to GH peptides because it mirrors natural sleep-phase GH release.

Pulse vs steady-state: why DAC changes the protocol

CJC-1295 no-DAC produces a sharp 30-minute GH spike that mirrors physiological pulsing. This is why it pairs with Ipamorelin at bedtime to ride the natural slow-wave sleep pulse. The DAC (drug affinity complex) variant binds albumin and produces a flat, week-long bleed of GH, which suppresses the pulsatile pattern researchers usually want to preserve. Most current protocols favour no-DAC + Ipamorelin for that reason.

Tesamorelin's niche

Tesamorelin is the only GHRH analogue with a regulatory dossier behind it. The 2 mg daily SC dose was approved for HIV-associated lipodystrophy in 2010 and is the figure most research protocols anchor to. Its visceral-fat selectivity is what distinguishes it from CJC-1295 in body-composition work. It's the comparator to reach for when the use-case is trunk adiposity rather than general recovery or sleep quality.

Longevity and metabolic peptides

MOTS-c and NAD+ sit in the metabolic-longevity bucket because both act on mitochondrial output rather than on the GH or GLP-1 axes that dominate the rest of this hub. Neither has a settled human dosing standard in 2026, so the figures below reflect commonly cited research-model ranges rather than approved protocols [2]. Researchers combining these compounds should start conservatively; human safety data is sparse.

MOTS-c: the mitochondrial-derived peptide

MOTS-c is a 16-amino-acid peptide encoded within the mitochondrial 12S rRNA gene. Most published research models use 5–10 mg subcutaneously, two to three times weekly. The investigational case is insulin sensitivity and exercise capacity in metabolic-syndrome models, not body recomposition in healthy adults. Human data remains thin enough that any titration should be treated as experimental [2].

NAD+ subcutaneous vs intravenous

NAD+ (nicotinamide adenine dinucleotide) subcutaneous protocols typically run 100–300 mg, two to five times weekly. IV infusions used in private UK clinics sit in the 250–1,000 mg per session range delivered over 1–4 hours. Subcutaneous administration trades peak plasma concentration for tolerability. IV produces flushing, chest pressure and gut cramping if pushed faster than approximately 250 mg/hour.

For readers stacking these with tissue-repair work, the BPC-157 and TB-500 dosing guide covers the recovery side. Readers chasing fat loss alongside mitochondrial support should cross-reference the Retatrutide vs Semaglutide vs Tirzepatide breakdown.

Skin and pigmentation peptides

GHK-Cu research protocols typically run 1–2 mg subcutaneously daily near the injection site for localised collagen and wound-healing work. Topical cosmetic formulations sit in the 0.05–0.2% range applied twice daily. The subcutaneous route concentrates copper delivery but carries a higher risk of injection-site irritation and transient flushing. Topical use dominates the commercial skincare literature because systemic absorption is negligible and tolerability is high. Start with topical GHK-Cu before attempting subcutaneous dosing if you have sensitive skin.

Melanotan II is dosed in a loading-then-maintenance pattern in research models: 0.25 mg subcutaneously daily, titrated upward by 0.25 mg every two to three days until a maintenance dose of around 1 mg is reached, then dropped to 1 mg twice weekly once target pigmentation is achieved. Reported adverse signals include nausea in the first 30–60 minutes post-injection, spontaneous erections, appetite suppression, and the appearance or darkening of naevi, the signal most commonly flagged in dermatology case reports as a reason to discontinue.

Readers stacking GHK-Cu with injury-recovery work should cross-reference the BPC-157 and TB-500 dosing guide for the tissue-repair protocols that pair most logically with copper-peptide use.

GH-axis and tissue-repair research model stacks

Published research clusters around three GH-axis/tissue-repair stack archetypes: lean-mass models (GH secretagogue + tissue repair), visceral-fat models (GLP-1/GIP agonist + lipolytic GHRH analogue), and recovery (synergistic tissue-repair peptides). None of these stacks has a registered bodybuilding indication in the UK as of 2026, and no GLP-1 receptor agonist holds MHRA authorisation for physique or performance use [unverified]. Cross-reference the compound-specific protocols linked below before starting any of these stacks.

The matrix below maps each research-model stack to its typical components, the outcome being modelled, and the comparator literature that should be read alongside it.

Why the recomp stack is the most-cited combination

CJC-1295 without DAC pairs with Ipamorelin because the GHRH analogue lifts baseline GH release whilst the ghrelin mimetic adds a pulse. The short half-life of both keeps the pulse physiological rather than tonic. BPC-157 is bolted on in research models where training volume is high enough to generate tendon or gut-lining stress.

Cutting-stack caveats

Tirzepatide's weekly titration in research models mirrors the obesity trial schedule. Read headline weight-loss percentages from SURMOUNT-1 and TRIUMPH-4 from the primary NEJM publications rather than secondary summaries [unverified]. Tesamorelin's visceral-fat signal comes from HIV-lipodystrophy literature and does not transfer cleanly to lean bodybuilding cohorts.

Buying research peptides in the UK in 2026

UK research-peptide purchases sit at the intersection of medicines law, advertising rules, and consumer-safety enforcement. A "not for human consumption" label does not, on its own, take a product outside MHRA scope [1]. Enforcement turns on presentation and function: marketing claims, route of administration, and whether the substance is positioned to modify human physiology all weigh more heavily than the disclaimer printed on the vial [1] [unverified]. If a supplier cannot articulate the legal basis for their product's status, that's a red flag.

For supplier diligence, the minimum pre-order checklist:

A 95% HPLC floor is the common commercial benchmark, but 98%+ is what I'd accept for anything injected in a research model [3][4] [unverified]. Purity alone does not validate identity, sterility, or endotoxin status, which is why the COA needs to cover all four.

Practical sourcing notes

Body Pharm UK's catalogue is organised by use-case, so the recovery row in the matrix above maps directly to how to dose BPC-157 and TB-500. The GLP-1 cutting row maps to Retatrutide vs Semaglutide vs Tirzepatide. If a vendor cannot produce a lot-matched COA on request, that's a hard stop, not a negotiation.

FAQs: UK peptide dosing

Common questions I get asked, answered in the order they tend to come up. Each answer is written to stand on its own if pulled into an AI overview or featured snippet.

How much bacteriostatic water should I use?

2 ml is the default for a 5 mg or 10 mg lyophilised vial. That gives clean unit-to-mg maths on a U-100 insulin syringe: with 10 mg in 2 ml, 10 units = 500 mcg. Use 3 ml only if your titration step is smaller than 100 mcg.

How long does a reconstituted vial last?

28 days refrigerated at 2–8°C is the working figure for peptides reconstituted with 0.9% benzyl alcohol bacteriostatic water. Sterile water shortens that to roughly 24 hours because it lacks the preservative. Keep light-sensitive compounds like BPC-157 in the original amber vial.

What's the difference between CJC-1295 DAC and no-DAC?

DAC binds to albumin and extends half-life to around 8 days, producing a sustained GH bleed. No-DAC (often sold as Mod GRF 1-29) clears within about 30 minutes and is typically pulsed three times daily with ipamorelin to mimic physiological GH release.

Are research peptides legal to buy in the UK?

Selling peptides labelled "for research use only" is not, by itself, prohibited, but the MHRA assesses regulatory status on presentation and function rather than the label [1]. Anything marketed with human dosing claims, route of administration, or therapeutic positioning falls inside medicines law.

Where do I find compound-specific protocols?

Recovery stacks are covered in detail in how to dose BPC-157 and TB-500. GLP-1 titration schedules sit in Retatrutide vs Semaglutide vs Tirzepatide.

Next steps

Start with the compound-specific protocol guide that matches your use-case: how to dose BPC-157 and TB-500 for recovery work, or Retatrutide vs Semaglutide vs Tirzepatide for weight-loss protocols. Before ordering from any supplier, request a lot-matched COA that confirms HPLC purity, mass-spec identity, sterility, and endotoxin status. Move on if the vendor won't provide one.

References

1. MHRA assessment of research peptides on presentation and function (not "research use only" labelling); preclinical-only evidence status of BPC-157, TB-500, and MOTS-c. Regulatory/evidence-status note; no single specific publication cited — unlinked.
2. Lee C, et al. The Mitochondrial-Derived Peptide MOTS-c Promotes Metabolic Homeostasis and Reduces Obesity and Insulin Resistance. Cell Metab. 2015. pubmed.ncbi.nlm.nih.gov/25738459
3. Supplier-diligence / COA purity-benchmark guidance (HPLC ≥95–98%, sterility, endotoxin). Sourcing standard; not a research study — unlinked.
4. MHRA position that "not for human consumption" labelling is non-determinative of medicinal status. Regulatory position; no single specific publication cited — unlinked.
5. Vendor/research-protocol dose figures (2026) for compounds lacking published human dosing trials. Vendor-protocol reference, not a peer-reviewed study — unlinked.
6. Standard UK reconstitution defaults and U-100 syringe conversion maths. Practical protocol convention; not a research study — unlinked.
7. Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021. pubmed.ncbi.nlm.nih.gov/33567185
8. Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022. pubmed.ncbi.nlm.nih.gov/35658024
9. Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med. 2023. pubmed.ncbi.nlm.nih.gov/37366315