GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, molecular weight 872.44 Da) is a synthetic hexapeptide that binds the growth hormone secretagogue receptor GHS-R1a, the same receptor ghrelin acts on. It arrives as a white lyophilized cake in a sealed vial, almost always 5 mg or 10 mg, and it must be reconstituted with bacteriostatic water before any of it can be dosed.
Typical doses run 100 to 300 mcg per injection, one to three times daily. A 100 mcg dose is 2 percent of a 5 mg vial, so the volume you draw is tiny no matter what you do. Choosing the right BAC water volume is what turns an awkward 3.5 unit draw into a clean 5 or 10 unit draw you can actually read on the barrel.
What You Need Before You Start
- GHRP-6 vial, lyophilized (5 mg or 10 mg)
- Bacteriostatic water, meaning sterile water preserved with 0.9% benzyl alcohol
- U-100 insulin syringes, 0.3 mL or 0.5 mL, 29 to 31 gauge, for dosing
- One 3 mL syringe with a longer needle for transferring the BAC water
- Alcohol swabs
- A refrigerator held at 2-8°C (36-46°F)
- A marker or label for writing the reconstitution date on the vial
Choosing Your BAC Water Volume
Concentration is vial strength divided by water volume, and nothing else. Add 2.5 mL of BAC water to a 5 mg vial and you get 2 mg/mL, which is 2000 mcg per mL, or 20 mcg for every unit on a U-100 insulin syringe. At that concentration a 100 mcg dose is 5 units, 200 mcg is 10 units, and 300 mcg is 15 units.
If 5 units is too small a volume for you to draw repeatably, use 5 mL of BAC water in the same 5 mg vial instead. That halves the concentration to 1 mg/mL (10 mcg per unit), so 100 mcg becomes 10 units and 300 mcg becomes 30 units. The costs are that a 0.3 mL syringe tops out at 30 units, the vial takes more fridge space, and you have added more preservative volume per dose.
Common GHRP-6 Concentration Examples
- 5 mg vial + 2.5 mL BAC water = 2 mg/mL, 20 mcg per unit (100 mcg = 5 units, 200 mcg = 10 units, 300 mcg = 15 units)
- 5 mg vial + 5 mL BAC water = 1 mg/mL, 10 mcg per unit (100 mcg = 10 units, 300 mcg = 30 units)
- 5 mg vial + 2 mL BAC water = 2.5 mg/mL, 25 mcg per unit (100 mcg = 4 units, 250 mcg = 10 units)
- 10 mg vial + 5 mL BAC water = 2 mg/mL, 20 mcg per unit (100 mcg = 5 units, 300 mcg = 15 units)
- 10 mg vial + 10 mL BAC water = 1 mg/mL, 10 mcg per unit (100 mcg = 10 units), though most vials cannot physically hold 10 mL
Vial capacity is a real constraint that catches people out. A standard 10 mL glass vial from a peptide supplier is often only rated to hold about 5 mL comfortably once you account for the stopper and headspace, so a 10 mg vial is usually mixed at 5 mL rather than 10 mL. Check the vial before you commit to a volume, because there is no way to add water back once you have drawn a dose.
Match your vial size to your protocol length. A 5 mg vial at 100 mcg twice daily is 25 days of use, which fits inside the 28 day refrigerated window. The same vial at 300 mcg three times daily lasts only about 5 days, so a 10 mg vial makes more sense for higher dose protocols.
Step-by-Step Reconstitution
- Take the vial out of the freezer and let it reach room temperature. Puncturing a cold stopper draws condensation into the vial.
- Swab both the GHRP-6 stopper and the BAC water stopper with alcohol and let them air dry for roughly 30 seconds.
- Draw your chosen volume of BAC water, for example 2.5 mL, into a 3 mL syringe.
- Insert the needle into the GHRP-6 vial at about a 45 degree angle so the tip points at the glass wall rather than the cake.
- Let the vacuum inside the vial pull the water in on its own. Press the plunger gently only if the vacuum stalls partway.
- Withdraw the needle and swirl or roll the vial for 30 to 60 seconds. GHRP-6 is highly water soluble and normally dissolves in under a minute.
- Hold the vial up to a light. The solution must be clear and colorless, with no strands, flakes, or floating particles.
- Write the reconstitution date, the mg strength, and the resulting mg/mL concentration on the vial.
- Refrigerate at 2-8°C right away.
Drawing an Accurate Dose
At 2 mg/mL a 100 mcg dose is 0.05 mL, which is 5 units. On a 0.3 mL U-100 syringe the unit marks sit roughly 3 mm apart, so 5 units is legible but leaves no margin for a rushed draw. Pull slightly past the target, flick the barrel to float air bubbles to the top, expel them back into the vial, then bring the plunger down to the exact mark while the needle is still in the vial.
If the relationship between units, mL, and mcg is not yet automatic for you, the insulin syringe reading guide walks the barrel markings line by line. To skip the arithmetic, enter your vial size, water volume, and target dose into the GHRP-6 calculator and it returns the exact unit count alongside a live syringe diagram.
Storage and Shelf Life
Sealed lyophilized GHRP-6 stored dry at -20°C stays stable for years, which is why suppliers ship it as a powder rather than a solution. Once you add bacteriostatic water, refrigerate at 2-8°C and plan to finish the vial within 28 days. The benzyl alcohol suppresses bacterial growth, but it does nothing about chemical degradation of the peptide itself, so the 28 day figure is a potency limit as much as a sterility limit.
Do not freeze a reconstituted vial. Ice crystals and repeated freeze thaw cycles physically break peptide chains, and the solution can look perfectly clear while a meaningful fraction of the material is no longer active. Store the vial in the body of the refrigerator rather than the door, where the temperature swings every time it opens, and keep it out of direct light.
For freezer versus refrigerator handling, travel rules, and what to do when a shipment arrives without a cold pack, see the peptide storage guide.
Timing Around the Appetite Response
GHRP-6 is the hungriest of the growth hormone releasing peptides. Because it activates GHS-R1a in the arcuate nucleus of the hypothalamus, it drives a sharp appetite spike that usually begins 15 to 20 minutes after a subcutaneous injection and fades over the following hour. Rodent work mapping c-fos expression in feeding related hypothalamic nuclei after GHRP-6 shows exactly this pattern of activation.
This is either the reason to use GHRP-6 or the reason to avoid it. On a bulking or appetite recovery protocol the hunger is the point. On a fat loss protocol it works against you, and ipamorelin is the better tool because it produces a comparable growth hormone pulse with essentially no ghrelin driven hunger.
Fasting state matters for the growth hormone response itself. Elevated glucose and insulin blunt the pituitary pulse, so the standard timing is first thing in the morning before food, and again before sleep at least 2 to 3 hours after the last meal. Wait about 20 to 30 minutes after injecting before eating so the pulse is not cut short, and be aware that on a pre bed dose the appetite spike lands right when you are trying to stop eating for the day.
How Long GHRP-6 Stays in Circulation
A pharmacokinetic study in nine healthy male volunteers dosed intravenously at 100, 200, and 400 mcg per kg found a bi-exponential disposition curve: a distribution half-life of 7.6 ± 1.9 minutes and an elimination half-life of 2.5 ± 1.1 hours. The very fast distribution phase is why the growth hormone pulse is sharp and short lived, and why multiple daily injections are the norm rather than a single large dose.
That short pulse also explains the dosing ceiling. Pushing a single dose far above 300 mcg does not produce a proportionally larger pulse because the pituitary somatotroph pool is finite, so protocols spread the total across two or three injections instead. The peptide half-life guide covers how these numbers translate into dosing frequency across compounds.
Reconstituting GHRP-6 for a Stack
GHRP-6 is normally paired with a GHRH analog such as CJC-1295 without DAC or sermorelin. The two act through separate receptors: the GHRH analog primes the somatotroph cells, while GHRP-6 triggers release and suppresses somatostatin. Human work from 1990 showed that a growth hormone releasing peptide plus GHRH produces a synergistic release, larger than either compound gives alone.
Reconstitute each peptide in its own vial and never combine the powders. If you want a single injection, mix both at the same concentration (for example 2 mg/mL each) so you can draw 5 units of each into one syringe immediately before injecting. A same session combined draw is fine, but do not store a pre-mixed syringe: the 28 day stability window applies to each peptide alone in bacteriostatic water, not to a blend.
Troubleshooting
- Powder still visible after a minute of swirling: let the vial sit at room temperature for 5 to 10 minutes and swirl again. GHRP-6 dissolves readily, so material that will not go into solution suggests a product quality problem.
- Cloudy solution or visible strands: discard the vial. Cloudiness means denatured peptide or contamination, and neither can be reversed.
- No vacuum when the needle enters the stopper: the seal has failed at some point, so treat the vial as non-sterile.
- The cake looks cracked or has shifted to one side before mixing: cosmetic movement during shipping is normal and does not affect potency.
- Yellow tint developing after a few weeks in the fridge: that is oxidation. Discard rather than dose.
- Persistent water retention or tingling in the hands: this is a known effect of sustained growth hormone elevation. Reduce the dose or the injection frequency.
Related Growth Hormone Secretagogues
The reconstitution math is identical across the GHRP family, only the target dose and the side effect profile change. GHRP-2 runs at 100 to 300 mcg with a milder appetite effect and slightly more cortisol and prolactin response. Ipamorelin is the selective option at 100 to 300 mcg with essentially no hunger, cortisol, or prolactin effect. Hexarelin is the most potent per microgram at 100 to 200 mcg but desensitizes the fastest. MK-677 covers the same receptor orally and needs no reconstitution at all.