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How to reconstitute HGH
HGH is the one compound here where the word "unit" means two completely different things, and confusing them is how people take three times the dose they intended. Somatropin is measured in international units (IU). An insulin syringe is marked in insulin units, which measure volume, not hormone. They are unrelated. This page gets the conversion right, with charts for every common vial size.
Two conversions, in order. Strength: 1 mg somatropin ≈ 3 IU, so a 12 mg vial is 36 IU. Then volume: insulin units = (dose IU ÷ vial IU) × water mL × 100. Mix to 10 IU/mL and the second step collapses to insulin units = IU × 10. Or skip the arithmetic with the reconstitution calculator.
What you need
- • A lyophilized somatropin vial, commonly 10, 12, 15, 36 or 100 IU. Some are labelled in mg instead, at roughly 3 IU per mg
- • Bacteriostatic water for a multi-dose vial. Many pharmaceutical HGH presentations ship with their own supplied diluent, which you should use if provided
- • A U-100 insulin syringe
- • Alcohol swabs, clean hands, a clean surface
The steps
Prep. Wash your hands. Swab the rubber stopper of both the compound vial and the bacteriostatic water with alcohol and let them air dry.
Draw your water. Pull the volume you decided on above into a syringe. This number is the single decision that sets everything downstream.
Add it slowly. Insert the needle and let the water run down the inside glass wall, not jetting straight onto the powder. Foam means sheared peptide.
Dissolve gently. Swirl the vial or roll it between your palms. Never shake. Wait until it is completely clear. Cloudiness or floating particles means do not use it.
Draw the dose. Work out your units from the chart above, swab the stopper again, and draw on a U-100 syringe, tapping air bubbles back out.
Label and refrigerate. Write the concentration and the date on the vial. In four weeks you will not remember either.
IU to insulin units chart
Find your vial, then read across to your daily dose. These are insulin units on the syringe barrel, not IU:
| Vial + water | Concentration | 1 IU | 2 IU | 3 IU | 4 IU |
|---|---|---|---|---|---|
| 10 IU + 1 mL | 10 IU/mL | 10 u | 20 u | 30 u | 40 u |
| 10 IU + 2 mL | 5 IU/mL | 20 u | 40 u | 60 u | 80 u |
| 12 IU + 1 mL | 12 IU/mL | ~8 u | ~17 u | 25 u | ~33 u |
| 15 IU + 1.5 mL | 10 IU/mL | 10 u | 20 u | 30 u | 40 u |
| 36 IU + 3 mL | 12 IU/mL | ~8 u | ~17 u | 25 u | ~33 u |
| 100 IU + 10 mL | 10 IU/mL | 10 u | 20 u | 30 u | 40 u |
Every row where the concentration is 10 IU/mL gives the same simple relationship: insulin units = IU × 10.
Mix to 10 IU per mL and the confusion disappears
The reason to aim for 10 IU/mL is not that it is more accurate, it is that it removes an entire category of mistake. At that concentration the conversion is a single decimal shift: 2 IU is 20 units, 3.5 IU is 35 units, and there is nothing to get wrong at 2am. A 10 IU vial takes 1 mL, a 15 IU vial takes 1.5 mL, a 100 IU vial takes 10 mL.
The 36 IU vials, which are extremely common, do not divide cleanly. Three millilitres gives 12 IU/mL, where a 2 IU dose is 16.67 units and you are rounding on every single injection. If you would rather not, 3.6 mL gives exactly 10 IU/mL and restores the clean conversion. Whether that is worth the odd-looking water volume is a matter of taste, but the arithmetic argument is real.
The mg and IU problem
Some vials are labelled in milligrams and some in IU, and the two are not interchangeable without a conversion factor. The convention for recombinant somatropin is 1 mg is approximately 3 IU, so:
- • A 4 mg vial is about 12 IU
- • A 5 mg vial is about 15 IU
- • A 12 mg vial is about 36 IU
- • A 10 mg vial is about 30 IU
The approximation matters because it is where a threefold error lives. Someone reading a chart written in IU while holding a vial labelled in mg, and assuming the numbers are the same, will dose three times high. If your vial and your protocol are written in different units, convert on paper first and write the result on the vial label.
Storage & beyond-use dating
Somatropin is more fragile than the peptides on the rest of this site. Reconstituted, it wants 2-8 °C at all times, and the usual working window is around 14 to 28 days depending on the product and diluent, shorter than the 28-day default you may be used to. Never freeze it: freezing denatures the protein and a thawed vial is not recoverable. Keep it out of light, do not leave it on the counter, and if the solution is cloudy or has visible particles after mixing, do not use it. Where a manufacturer supplies its own diluent and its own in-use figure, that figure overrides the general rule.
Common mistakes
- • Reading IU as insulin units. A 2 IU dose is 20 units at 10 IU/mL, not 2. This is a tenfold error and it is the most common one.
- • Treating mg and IU as the same number. 1 mg is about 3 IU, so a threefold overdose is one careless assumption away.
- • Freezing the reconstituted vial. Peptides tolerate it poorly; somatropin does not tolerate it at all.
- • Using a chart from a different vial size. A 36 IU vial in 3 mL is not the same concentration as a 10 IU vial in 1 mL.
- • Discarding a manufacturer-supplied diluent in favour of bacteriostatic water without checking the product's own storage guidance.
Somatropin is a prescription medicine everywhere it is legally available, and in the United States its distribution and possession for non-approved uses is specifically restricted under federal law, more tightly than for most compounds covered on this site. Approved indications are growth hormone deficiency and a small number of related conditions, not body composition or anti-ageing. HGH affects insulin sensitivity, glucose handling and fluid balance in ways that need monitoring. This page explains reconstitution mechanics; it is not medical advice, not a recommendation, and not a route around a prescription.
Skip the arithmetic
OptiPin's free reconstitution calculator takes your vial size, water volume and target dose and returns the exact units, flagging the draws that will not fit a syringe. The app then logs every injection, tracks what is left in the vial and warns you before it runs out or expires. iOS, on-device, no account.
Open the calculatorFrequently asked questions
How much bacteriostatic water do you add to a 10 IU HGH vial?
One millilitre. That gives 10 IU/mL, which makes the conversion trivial: insulin units equal IU times ten, so a 2 IU dose is 20 units on the syringe. Two millilitres also works and gives 5 IU/mL, doubling the numbers, but the clean tenfold relationship is worth preserving.
How many insulin units is 2 IU of HGH?
At 10 IU/mL it is 20 insulin units. At 12 IU/mL, which is what a 36 IU vial in 3 mL gives, it is about 17 units. The IU is the dose of hormone; the insulin unit is a measure of volume on the syringe. They are only related through the concentration you created.
How many IU is 1 mg of HGH?
Approximately 3 IU per milligram is the standard conversion for recombinant somatropin. So a 4 mg vial is about 12 IU, a 5 mg vial about 15 IU, and a 12 mg vial about 36 IU. Never assume a vial labelled in mg and a protocol written in IU are using the same numbers.
How do I reconstitute a 36 IU HGH vial?
Three millilitres gives 12 IU/mL, which is the common approach but leaves you rounding, since a 2 IU dose works out at 16.67 units. Using 3.6 mL gives exactly 10 IU/mL and restores the clean conversion where insulin units are simply IU times ten.
How long does reconstituted HGH last in the fridge?
Typically 14 to 28 days at 2-8 °C, which is shorter than the 28-day default for most peptides, and it varies by product and diluent. If the manufacturer supplies a diluent and an in-use figure, follow those. Never freeze it, since freezing denatures somatropin irreversibly.
Sources & further reading
- Somatropin - DailyMed labels (per-product reconstitution, diluent and in-use storage).
- Bacteriostatic Water for Injection, USP - DailyMed label (multi-dose diluent).
- 21 U.S.C. 333(e) - distribution of human growth hormone (the specific US restriction on non-approved HGH distribution).
U-100 syringe: 100 units = 1 mL. Vial strengths and fill volumes vary between suppliers, so always verify the stated strength on your own vial before calculating. This page is educational and is not medical advice.
Related
Reconstitution calculator · Somatropin profile · TRT vs HGH vs peptides · Tesamorelin reconstitution · hCG dose calculator (also IU-dosed) · Syringe units chart