Peptides explained plainly.
Every compound explained in one line, then in full — what it is, how people use it, and the part most sites skip: whether anyone has actually tested it in a human being.
How much is actually known — all 45 full entries
Every compound, one line each
The fastest way in. Search or scan, then follow a name through to its full entry where one exists. The stripe and label on each row tell you how much is actually known about it.
This is a reference, not advice. The dose figures below are what appears in the published trial literature and in common practice — recorded so you can recognise and check them, not prescribed. Most of these compounds are not approved medicines, several have no human safety data at all, and none of this substitutes for a doctor who knows your history. PepInfo does not sell anything.
The words you will keep seeing
Nine terms cover almost everything written about peptides. Learn these and the rest of the page reads easily.
- mcg and mg
- Units of weight. 1 mg = 1000 mcg. Peptide doses are usually in micrograms, vials are usually labelled in milligrams. Mixing the two up by a factor of a thousand is the most common and most dangerous beginner error.
- Lyophilised
- Freeze-dried. Peptides arrive as a small white powder cake in a sealed vial. In that state they are stable for a long time. They only become fragile once liquid is added.
- Reconstitution
- Adding liquid to the powder to make it injectable. You choose how much liquid. It does not change the dose — only how many units you draw to get it.
- BAC water
- Bacteriostatic water — sterile water with a preservative that stops bacteria growing. It is what lets you use a vial repeatedly over weeks. Plain sterile water has no preservative and makes a vial single-use.
- SubQ and IM
- SubQ is subcutaneous — into the fat just under the skin, with a short insulin needle. That covers nearly everything here. IM is intramuscular, deeper and rarely needed for peptides.
- Units
- The markings on an insulin syringe. A standard U-100 syringe holds 1 mL across 100 units, so 1 unit = 0.01 mL. Units are a volume, not a dose — the same 10 units can be very different amounts of peptide.
- Half-life
- How long until half of a dose has cleared your system. It is what decides the schedule: a half-life of an hour means dosing daily barely overlaps, a half-life of a week means doses stack on each other.
- Titration
- Building the dose up in steps instead of starting at the target. For the GLP-1 drugs this is not optional — nearly all the severe sickness people report comes from going up too fast.
- Cycling
- Running something for a set period, then stopping for a while. Some compounds stop working if used continuously. A break is also the only way to find out whether something is still doing anything.
Read a compound in this order
Most people jump to the dose. The dose is the least useful number on the page until the three questions before it have been answered.
Check the badge
It tells you whether anyone has ever tested this in a person. That one fact decides how seriously to take everything else on the card.
Read how it works
One paragraph, in plain terms. If a claimed benefit has nothing to do with how the compound actually works, be suspicious of the claim.
Read the warnings
Amber means be careful. Red means do not. A few compounds here have one specific, documented reason to leave them alone.
Then the doses
A table of how much, how often and where — broken down by what people are using it for. Last, not first.
The full entries
The 45 compounds with a complete write-up: how it works, dose tables by goal, what people report and when, and the cautions. Filter by category or by how strong the evidence is.
The four things every protocol depends on
These apply regardless of compound. Most protocol failures — and most avoidable harm — come from getting one of these wrong rather than from the peptide itself.
Reconstitution
Peptides arrive lyophilised — freeze-dried powder — and must be dissolved in bacteriostatic water before use.
- Let the vial reach room temperature first. Cold vials and cold water dissolve badly.
- Aim the water down the inside wall of the vial, not straight onto the powder cake.
- Swirl gently, or leave it. Never shake — agitation shears the peptide chain.
- The volume of water you choose does not change the dose, only the number of units you draw. More water is easier to measure accurately.
Storage
Peptides degrade with heat, light and time. A mishandled vial is a weaker vial, and there is no way to tell by looking.
- Sealed and lyophilised: stable in a freezer for years, in a fridge for months.
- Once reconstituted: refrigerate at 2–8 °C and use within about 3–4 weeks. Some peptides are considerably shorter.
- Keep it dark. Foil or the original carton is enough.
- Do not freeze a reconstituted vial. Ice crystals destroy the peptide.
- Bacteriostatic water contains 0.9% benzyl alcohol, which is what allows multiple draws. Sterile water does not — a vial made up with sterile water is single-use.
Injection
Almost everything here is subcutaneous — into the fat layer, not the muscle. A short insulin needle makes that hard to get wrong.
- 29–31 gauge, 8 mm (5/16") insulin syringe. U-100 markings are the standard scale.
- Abdomen two inches either side of the navel, outer thigh, or the back of the upper arm.
- Pinch, insert at 45–90°, inject slowly, withdraw. Alcohol-swab the site and the vial stopper first.
- Rotate sites every time. Repeated injection into one spot causes lipohypertrophy — hardened tissue that absorbs unpredictably.
- One needle, one use. Never share, and dispose of sharps in a proper bin.
When you dose changes what it does
| Class | When | Why it matters |
|---|---|---|
| GH secretagogues | Fasted, before bed or 2h from food |
Insulin blunts growth hormone release. Dosing after a meal wastes the injection. Bedtime dosing lands on the body's own overnight GH pulse. |
| GLP-1 agonists | Same day weekly, food irrelevant |
A week-long half-life means the exact hour does not matter. Consistency of day does — it keeps blood levels flat rather than sawtoothed. |
| Repair peptides | Split through the day | Short half-lives. BPC-157 twice daily beats the same total dose once daily, because the tissue sees it for longer. |
| Nootropic peptides | Morning | Semax and Selank are stimulating enough to disrupt sleep if taken late. |
| Cycling | 4–12 weeks on, equal time off |
Receptor-mediated compounds desensitise — the ghrelin agonists fastest. Time off restores response. It is also the only way to find out whether a compound is still doing anything. |
Is the vial alright?
You cannot test purity at home, but you can spot a vial that has been damaged in transit or storage. Look before you add water — once it is mixed, you have lost the clearest signal.
A white, fluffy cake
Properly freeze-dried powder sits as a light cake covering the bottom of the vial. This is what a good vial looks like.
Clear once mixed
After gentle swirling the solution should be completely clear, with nothing floating and no cloudiness.
Small clumps
Minor compaction happens in shipping. If the clumps dissolve completely with gentle swirling, the vial is fine.
Powder up the sides
Usually just static from transit. Tap it down and check the cake underneath still looks intact.
Collapsed, melted or glazed
The cake has gone glassy or slumped. That means heat got to it in transit. Do not use it.
Cloudy or specked after mixing
Persistent cloudiness, particles or a film means degraded or contaminated product. Discard it — do not inject it.
Looking right is not the same as being right. A vial can look perfect and still be underdosed, be a different peptide entirely, or carry endotoxin — independent testing has found all three. If a supplier publishes a certificate of analysis, check the batch number on it matches the number on your vial. A certificate for a different batch tells you nothing. See a supplier that publishes them
We rate MrPep for UK supply
PepInfo doesn't sell anything, so we have no stake in where you buy. When people ask, we point them at MrPep — a UK supplier that publishes a certificate of analysis for every batch it ships, which is the one thing that separates a real supplier from a reseller with a nice website.
Stock is held in the UK, so there's no customs lottery, and each product page carries the batch number you can check against the certificate.
- Independent third-party COA published per batch
- UK-held stock, UK and EU shipping
- Batch numbers you can verify yourself
- Consumables too — BAC water, insulin syringes, wipes
MrPep sells research compounds. Whatever you buy and wherever you buy it, the evidence tiers on this page still apply.
Keep a log — Injectly
Once you are running more than one thing, or anything on a weekly schedule, memory stops being good enough. Injectly is a free iPhone app for logging injectables: what you took, how much, when, and which site you used, so you can rotate properly and actually see your own history.
It also handles blend vials with a per-ingredient breakdown, sends reminders that match your cadence, and exports everything to CSV. No ads, and your log stays on your device.
What you can actually get in the UK
Most of this page has no legitimate consumer route in Britain — it is sold as a research compound because it is not a licensed medicine here. A handful of things people meet through sites like this one are simply available, and it is worth knowing which.
Each compound's own entry above carries its UK status too, including the ones where the answer is that there is no way to buy it here properly. A registered pharmacy will be on the GPhC register — if it is not, that tells you what you need to know.
Injector pens and the marking nobody checks
Amazon, eBay and dozens of peptide sites all sell auto-injector pens, cartridges and needles. Most buyers compare the price and the photo. Almost nobody checks the one thing that actually tells you whether the device was ever assessed for safety.
What the mark means
A CE or UKCA mark on a medical device says the manufacturer has been through a conformity assessment — dose accuracy, materials that are safe against skin and drug, sterility of anything that breaks the skin, and a traceable batch if something goes wrong.
What "CE" often means online
An unregulated marketplace listing can print those two letters on a box with nobody having assessed anything. There is also a near-identical "China Export" logo with narrower spacing. If a seller cannot produce a Declaration of Conformity naming the device, treat the mark as decoration.
Why it matters here
A pen that under-doses quietly ruins a protocol you then blame on the peptide. A cartridge that is not properly sterile, or plastic that leaches into the solution, is a problem you will not see until it is an infection. This is the one part of the setup where cheap is genuinely risky.
Ask for the paperwork, not the logo
Whoever you buy from, ask one question: can you send me the Declaration of Conformity for this device? A supplier holding genuine certification answers that in a sentence. One that cannot will change the subject.
MrPep stocks the consumables side of this — auto-injector pens, sterile glass cartridges, pen needle tips, reconstitution needles, syringe filters and pre-injection wipes — and is in the process of publishing certification documentation for the devices in that range. Until that is live on their product pages, ask them for it directly, exactly as you would ask anyone else.
- Auto-injector pens and sterile glass cartridges
- Pen needle tips, reconstitution needles, syringe filters
- UK-held, so no customs lottery on a part you need this week
Certification documentation for the device range is being published. Ask for the Declaration of Conformity before you buy — from them or from anyone.
Why a pen that arrives already mixed is a bad buy
Peptides ship as freeze-dried powder for a reason: that is the form that survives. The moment one is in liquid, a clock starts. A pre-filled pen means somebody else started that clock, at a date and temperature you will never know.
What you are actually buying
A solution of unknown age, mixed at an unknown concentration, that has been through a warehouse, a courier and possibly customs at whatever temperature those involved.
- The clock started without you. Reconstituted peptide keeps for around three to four weeks refrigerated. Nobody tells you when the pen was filled, and degradation is completely invisible.
- You cannot check the maths. With a vial you know the milligrams on the label and you chose the water, so the dose is arithmetic you can verify. In a sealed pen, the concentration is whatever the seller says it is.
- No batch to check. A vial carries a batch number you can match against a certificate. A pre-fill usually severs that link entirely.
- Multi-dose needs a preservative system. Something drawn from repeatedly over weeks has to resist bacterial growth. A licensed pen has that formulation validated. An informal pre-fill may simply not.
- You lose every dial. No titrating up slowly, no dropping back when side effects bite, no thinning it out so a small dose lands on a readable part of the scale.
What you get instead
The stable form, mixed by you on the day you start, in a device you keep and reload. More steps, and every one of them is a step you can actually verify.
- Stable until you decide. Sealed lyophilised powder holds for months in a fridge and years in a freezer. You start the clock, so you know exactly where you are in it.
- You set the concentration. More water spreads a small dose across more units on the syringe, which is the difference between measuring accurately and guessing.
- You can inspect it. A good powder cake is white and fluffy; a collapsed or glazed one has been heat-damaged. That is a check a sealed pen takes away from you.
- Cheaper over time. You buy the pen once and reload cartridges, rather than paying for a disposable device with every refill.
One important exception. A genuine Ozempic, Wegovy or Mounjaro pen from a pharmacy is not what this section is about. Those are manufactured under pharmaceutical conditions with a validated formulation, a proper cold chain and a regulator behind them — the pre-filling is the whole point and it is done properly. The argument above is about informally filled pens from research-compound sellers, which are a different thing wearing a similar shape.
Hair serums, and making your own instead
A copper-peptide hair serum is a peptide sitting in solution on a shelf — often for a year, usually at a concentration the label never states, alongside fragrance and preservatives added to keep the product saleable rather than to keep the peptide intact. It is the pre-filled pen problem in a dropper bottle.
Mixing AHK-Cu yourself
AHK-Cu is the copper tripeptide aimed at hair follicles, where GHK-Cu is aimed at skin. Bought as powder and mixed fresh, you control the strength, you know its age, and you are not paying for a bottle of mostly water.
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Reconstitute with bacteriostatic water
A 50 mg vial in 5 ml of BAC water gives you a 1% solution — a sensible starting strength for scalp use. Use 10 ml for roughly 0.5% if you would rather start gentler. Aim the water down the vial wall, swirl, never shake.
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Use bacteriostatic, not sterile, water
The preservative in BAC water is what lets you keep drawing from the same vial over several weeks. Sterile water has none, which makes anything left over a growing medium.
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Clean the scalp and the device
Wash and fully dry the scalp. Soak the microneedling head in 70% isopropyl alcohol for a few minutes before and after every session, and let it dry. This step is the difference between a treatment and an infection.
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Keep the needles short
0.25 mm to 0.5 mm is the range for home scalp use. Anything at 1 mm or above belongs in trained hands — it draws blood, hurts considerably, and raises the infection and scarring risk sharply without clearly working better.
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Roll, then apply
Work over the area in a few directions with light pressure, then apply a few drops of the solution and spread it with clean fingertips. Microneedling is what gets a large molecule past the outer layer of skin — without it, most of a topical peptide never arrives.
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Once a week, not daily
At 0.5 mm, once a week gives the skin time to recover. At 0.25 mm some people go two or three times. More often is not better; irritated skin is not repairing.
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Store it cold and dark, and use it up
Fridge, out of the light, and use within about three to four weeks. Copper solutions are usually faintly blue; if it turns cloudy or throws a deposit, bin it.
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Do not stack it with acids or vitamin C
Copper peptides and strong acids or vitamin C serums interfere with each other. Put them on different days rather than layering them, and patch test before the first full session.
Work out the draw, then see the curve
Pick a compound to load its typical vial, dose and half-life, or enter your own. The top panel gives you the mark on the syringe. The one below shows what the dose does to blood levels over time — where it peaks, what is left when the next one is due, and where it settles.
Draw to this mark
10
units on a U-100 insulin syringe
Show what repeated doses do to blood levels Optional. Useful for understanding why the schedule is what it is.
Each dose lands on top of whatever has not cleared yet. Levels climb for a while, then settle — that plateau is what your body actually sees day to day.
The stacks people actually run
These are the combinations that recur, described as they are commonly structured. They are conventions rather than validated regimens — no combination on this page has been through a trial as a combination.
| Protocol | Compounds | Typical structure | The reasoning |
|---|---|---|---|
| Soft tissue repair | BPC-157 + TB-500 | BPC 250–500 mcg 2× daily near the site TB-500 2–2.5 mg 2× weekly 4–8 weeks |
One acts locally on the injury, the other systemically on cell migration. The most common pairing in the recovery space — and entirely animal-evidenced. |
| GH pulse | CJC-1295 no-DAC + Ipamorelin | 100 mcg + 200–300 mcg same syringe, 1–3× daily fasted / pre-bed, 8–12 weeks |
A GHRH analogue and a ghrelin agonist hit different receptors; together the pulse is far larger than either alone. Ipamorelin is chosen for not raising cortisol or prolactin. |
| Metabolic | A single GLP-1 agonist | Weekly, titrated monthly indefinitely, under review |
The one area where stacking is generally the wrong instinct. These are approved drugs with defined titrations; adding compounds mostly adds side effects and confounds attribution. |
| Skin and appearance | GHK-Cu (topical) + Glow blend | Topical daily injectable 4–6 weeks, then a break |
Topical GHK-Cu is the part with controlled human trials behind it. The injectable blend is the speculative addition, and the copper load is why it is not run continuously. |
| Cognitive | Semax + Selank | Intranasal, mornings 10–14 day courses with breaks |
Semax for drive and focus, Selank to take the edge off it. The Russian clinical convention is short courses rather than continuous use. |
| Mitochondrial | MOTS-c ± SS-31 | MOTS-c 5–10 mg 2–3× weekly 5 days on / 2 off, 8 weeks |
Two different mitochondrial mechanisms — AMPK signalling and cardiolipin stabilisation. Expensive, and the human evidence is thin for one and mixed for the other. |
Signals worth acting on
Most side effects are dose-related and settle. These are the ones that are not — where the right response is to stop and get seen rather than to push through.
| What you notice | Associated with | What it may be | What to do |
|---|---|---|---|
| Severe upper abdominal pain going through to the back | GLP-1 agonists | Pancreatitis | Stop. Urgent medical assessment — this one is an emergency. |
| A mole darkening, growing or changing shape | Melanotan II | Dysplastic change; melanoma has been reported | Stop and see a dermatologist. Do not wait to see if it settles. |
| Erection lasting over four hours | Melanotan II, PT-141 | Priapism | A&E immediately. Delay causes permanent damage. |
| Shaking, sweating, confusion, sudden hunger | IGF-1 LR3; GLP-1 with insulin or a sulfonylurea | Hypoglycaemia | Fast-acting sugar now, then medical review of the whole regimen. |
| Numb or tingling hands, especially on waking | GH secretagogues, MK-677, CJC-1295 DAC | Fluid retention causing carpal tunnel compression | Reduce the dose or stop. It reliably resolves — it is the clearest sign the dose is too high. |
| Rising fasting glucose or new insulin resistance | MK-677, any sustained GH elevation | Direct metabolic effect of GH | Stop and retest. This is the effect most often ignored until it is not reversible quickly. |
| Spreading redness, heat and swelling at an injection site | Any injectable | Cellulitis or abscess | Medical review. Injection-site reactions are common; spreading infection is not one. |
| Persistent vomiting and inability to keep fluids down | GLP-1 agonists during titration | Excessive gastric slowing, dehydration | Stop escalating, drop back a dose, seek review if it continues past a day or two. |
Common questions
What does "research use only" actually mean?
It means the compound has not been approved as a medicine for the use in question, and is sold for laboratory work rather than for people. It is a statement about regulatory status and about how the product was sold — not a claim that it is safe, and not a claim that it is dangerous. Several compounds on this page are sold that way in one country and prescribed as approved drugs in another.
Why does the evidence tier matter more than the dose?
Because a dose is only meaningful if somebody established it. For an approved drug like semaglutide, the titration schedule comes from trials in thousands of people that measured what happened at each step. For a compound like BPC-157, the figure is a convention that propagated through forums — nobody ran a dose-finding study in humans.
Both appear on this page as "a dose". They are not the same kind of number, and the tier badge is there so you never have to guess which one you are looking at.
Bacteriostatic or sterile water?
Bacteriostatic water, for anything you will draw from more than once. It contains 0.9% benzyl alcohol, which suppresses bacterial growth and is what makes a multi-dose vial viable for weeks in a fridge.
Sterile water has no preservative. A vial reconstituted with it is single-use — anything left is a growth medium. The exception is for infants, where benzyl alcohol is contraindicated.
How long does a reconstituted vial last?
Roughly three to four weeks refrigerated at 2–8 °C for most peptides, with bacteriostatic water. Some are markedly less stable and some blends shorter still.
Degradation is invisible — a vial that has been left out or repeatedly warmed looks identical to a good one. If the powder went cloudy, stringy, or the solution will not clear, discard it.
Do I need to cycle?
For receptor-mediated compounds, yes — the ghrelin agonists in particular desensitise, and hexarelin notably fast. Running them continuously produces a diminishing response for the same cost and the same side effects.
There is a second reason that applies to everything here: a break is the only way to find out whether the compound is still doing anything. Without one, you are paying for a habit rather than an effect.
Why are SARMs not on this page?
They are not peptides — they are non-steroidal small molecules acting on the androgen receptor, a different class with a different risk profile, most notably hepatotoxicity and suppression of natural testosterone production. They get grouped with peptides commercially rather than pharmacologically.
A few non-peptides that are genuinely inseparable from peptide practice are included and labelled as such: MK-677, 5-Amino-1MQ and the NAD+ precursors.
Does the amount of water change the dose?
No. The vial contains a fixed amount of peptide however much water goes in — more water simply means you draw a larger volume for the same dose.
It changes accuracy, though. If your dose lands at 2 units on the syringe, adding more water spreads it across 10 or 20 units, where a small error in the plunger position matters far less. That is the practical reason to use more rather than less.
Are compounded and "grey market" versions the same thing?
No. A compounding pharmacy operates under pharmacy regulation, with a prescription behind it and some accountability for what is in the vial. Research-chemical suppliers do not, and the actual contents vary — independent testing has repeatedly found peptides underdosed, misidentified, or carrying endotoxin.
Where a supplier publishes third-party certificates of analysis, check that the batch number on the certificate matches the vial in your hand. A certificate for a different batch tells you nothing about yours.
For UK buyers we rate MrPep, which publishes a certificate per batch and holds stock in the UK.
Most of this is less proven than it sounds
Of the 45 compounds here, nine have been approved by a regulator for a human use. Twenty-four have never been tested in a person in any controlled way. The gap between how confidently these compounds are discussed and how much is actually known about them is the single most important thing on this page.
That is not an argument that none of it works — several of these have real biology behind them and a few are genuinely promising. It is an argument for reading the tier before the dose, telling a doctor what you are taking, and treating a confident forum post as what it is.
Educational reference only. Not medical advice, and no substitute for a clinician who knows your history.