HGH (Somatropin)
Also known as Human Growth Hormone, Somatropin, rhGH, Recombinant Growth Hormone, Genotropin, Norditropin, Omnitrope
HGH is recombinant human growth hormone, a 191 amino acid protein identical to what the pituitary makes. It is an approved drug for growth hormone deficiency and is used off-label for fat loss, muscle preservation, recovery, and anti-aging.
Reviewed by the amino101 editorial team. , first published .
Quick start
What people commonly do. Not a prescription.- Typical dose
- 1 to 4 IU per day
- How often
- once daily, or split into two doses
- Where
- Subcutaneous, belly or thigh, rotate sites; intramuscular is less common
- Timing
- Morning on waking or before bed; splitting AM and PM softens the peak; some inject after training
- Effects timeline
- water retention and deeper sleep 1 to 2 weeks, skin and recovery 3 to 4 weeks, fat loss 8 to 12 weeks, lean mass 3 to 6 months
- Storage
- Lyophilized in fridge 2 to 8 C; reconstituted in fridge 2 to 8 C, use within 2 to 4 weeks depending on product
- Cycle length
- 3 to 6 months minimum for body composition; medical replacement is ongoing
- Break between
- many run it continuously with bloodwork; 4 to 8 weeks off if IGF-1 or glucose drift up
Overview
Human growth hormone is a 191 amino acid single chain protein made by the pituitary. Technically it is a protein rather than a small peptide, but it belongs in any peptide database because it is the hormone every secretagogue is trying to release. Recombinant somatropin has been available since 1985 and is approved for pediatric and adult growth hormone deficiency, Turner syndrome, chronic kidney disease in children, HIV wasting, short bowel syndrome, and other conditions. Brands include Genotropin, Norditropin, Humatrope, Omnitrope, and Saizen, and unlicensed generics dominate the grey market.
The clinical evidence in true deficiency is strong. Replacement in growth hormone deficient adults improves lean mass, reduces fat mass, improves lipid profiles, bone density, and quality of life. In healthy adults the picture is more modest. A frequently cited 1990 study in older men showed increased lean mass and reduced fat with 6 months of injections, and later meta-analyses of healthy older adults confirmed body composition changes of a few kilograms but found no improvement in strength or function and a meaningful rate of side effects like edema, joint pain, and carpal tunnel syndrome.
In sports and body composition circles, HGH is used at doses of 2 to 6 IU per day for fat loss, muscle fullness, and recovery, often for months at a time. The fat loss and water shifts are real; the effect on true muscle protein is smaller than most people expect and is amplified mainly when combined with anabolic hormones. The main concerns with sustained use are insulin resistance, elevated blood glucose, fluid retention, joint issues, and theoretical cancer promotion from chronically elevated IGF-1. Because it is a controlled prescription drug in most countries, the legal status is also very different from research peptides.
How it works
Somatropin binds the growth hormone receptor on the liver, muscle, fat, and bone, activating the JAK2-STAT5 signaling cascade. In the liver this drives production of IGF-1, which mediates most of the anabolic and growth promoting effects on muscle, cartilage, and bone. Growth hormone also has direct effects on fat cells, stimulating lipolysis and reducing lipid uptake, and on metabolism, where it raises blood glucose by opposing insulin and promoting fat oxidation. Exogenous somatropin suppresses the body's own pulsatile growth hormone production through negative feedback at the hypothalamus and pituitary, which is why the effects feel different from secretagogues and why some people split doses to mimic natural pulses.
Where the research stands
Growth hormone deficiencyStrong evidence
- Adult GHD replacement. Approved use; clinical trials show improved body composition, lipids, bone density, and quality of life.
- Pediatric growth failure. Approved use with decades of clinical data on growth velocity and final height.
HIV wasting and short bowel syndromeStrong evidence
- HIV-associated wasting. Approved indication supported by RCTs showing lean mass gain.
- Short bowel syndrome. Approved indication for nutritional support alongside specialized diet.
Body composition in healthy adultsModerate evidence
- Lean mass gain and fat loss. RCTs and a systematic review in healthy older adults show a few kilograms of lean mass gained and fat lost.
- Strength and function. The same trials found no improvement in strength or physical function.
Athletic performanceWeak or mixed
- Sprint capacity. One RCT in recreational athletes found about a 4 percent sprint improvement and no change in strength, power, or endurance.
Anti-agingWeak or mixed
- Longevity and vitality. No trial shows extended lifespan or healthspan; the older adult data shows body composition change with a meaningful side effect rate.
- human RCTSix months of growth hormone in men over 60 increased lean mass by about 8 percent and reduced adipose mass by about 14 percent.
- human RCTMeta-analysis of healthy older adults found small gains in lean mass and losses in fat mass but no improvement in strength, with higher rates of edema, joint pain, and carpal tunnel.
- clinical (approved drug)Growth hormone replacement in deficient adults improves body composition, lipid profile, bone density, and quality of life.
- human RCTGrowth hormone increased sprint capacity by about 4 percent in recreational athletes but did not improve strength, power, or endurance.
- human RCTGrowth hormone administration in healthy adults reduces insulin sensitivity and raises fasting glucose in a dose dependent way.
Rodent and in vitro mean no human data for that finding. Human pilot means small, often uncontrolled. Human RCT means randomized and controlled. Clinical means an approved drug with regulatory data.
Levels over time
Modeled from the half-life. Illustrative, not measured.A half-life of 2.5 h against dosing every 24 h means each dose has cleared before the next. Nothing stacks; you start from zero every time, and the tissue effect is what carries over.
Growth hormone itself clears in hours but the IGF-1 it triggers lasts about a day, which is why once daily dosing works and why some people split the dose to soften the peak and mimic natural pulses.
HGH (Somatropin) dosage and protocols
Most people start low and hold for a few weeks before considering an increase, then run 3 to 6 months at a working dose. Medical replacement is continuous and weight based. There is no taper requirement, though some step the dose down over a week or two to let their own pituitary output resume smoothly.
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Anti-aging, recovery, skin | 1 to 2 IU | once daily on waking or before bed | Subcutaneous |
| Body composition | 3 to 4 IU | split into two doses, morning and evening or post-training | Subcutaneous |
| Injury recovery support | 2 IU | once daily before bed | Subcutaneous, often with BPC-157 or TB-500 |
| Medical adult replacement | roughly 0.6 to 1.5 IU (0.2 to 0.5 mg) | once daily, titrated to IGF-1 | Subcutaneous, prescribed and monitored |
Growth hormone raises blood glucose for several hours, so many people inject on waking before eating or after training, and avoid dosing right after a large carbohydrate meal. Bedtime dosing suppresses the natural nighttime pulse but is convenient and helps sleep for some. Splitting AM and PM reduces the peak and the tingling and water retention that come with it.
1-2 IU daily for anti-aging and recovery; 3-6 IU for body composition; medical replacement is typically weight based and lower
Dose calculator
U-100 insulin syringeUnits are a volume on the syringe, not an amount of peptide. Concentration changes every time you change the water volume. The standalone calculator explains the math.
| Vial | Suggested water | Concentration | Low dose draw |
|---|---|---|---|
| 10 IU | 1 mL | 10 IU/mL | 10 units |
| 12 IU | 1 mL | 12 IU/mL | 8.3 units |
How to reconstitute HGH (Somatropin)
- 1
Wash your hands and wipe the work surface. Swab both vial stoppers with alcohol and let them dry.
- 2
Pick the water volume with the calculator above and write it on the vial. The concentration means nothing without it.
- 3
Draw the bacteriostatic water into a mixing syringe.
- 4
Insert at an angle and let the water run down the inside wall. Never squirt it straight onto the powder.
- 5
Swirl gently or leave it to dissolve. Do not shake.
- 6
Label with the date and water volume. Store in the fridge at 2 to 8 C and use within about 4 weeks.
- 7
Unmixed vials keep for months in the fridge and longer in the freezer, sealed and out of light.
- Full walkthrough with syringe reading and site rotation: reconstitution guide.
- ✓White, fluffy cake
Lyophilized powder should look like a small white puck or fluffy cake at the bottom of the vial. That is a proper freeze-dry.
- ✓Clear after mixing
Once dissolved the solution should be water-clear with nothing floating in it.
- !Slight clumping
Small clumps that dissolve with gentle swirling are fine. Shipping compacts powder.
- ✕Collapsed or melted
Powder stuck to the sides, glassy, or shrunken means it got hot in transit. Contact the vendor.
- ✕Cloudy or particles
Persistent cloudiness or visible particles after mixing means degraded or contaminated product. Do not use it.
- Week 1 to 2
Water retention, puffy hands and feet, deeper sleep, some tingling in the fingers, especially above 2 IU.
- Week 2 to 4
Fluid effects usually plateau, skin looks fuller, recovery between sessions improves, fasting glucose may tick up.
- Week 4 to 12
Gradual fat loss around the midsection, muscles look fuller from water and glycogen, IGF-1 elevated on bloodwork.
- Month 3 to 6
A few pounds of lean mass and measurable fat loss in most responders; strength gains are not expected from the hormone itself.
Interactions and stacking
IGF-1 LR3synergistic
Direct IGF-1 signaling on top of liver derived IGF-1 gives a stronger anabolic effect but roughly doubles the hypoglycemia and cell growth concern.
BPC-157compatible
Common recovery pairing; growth hormone drives collagen synthesis while BPC-157 targets local repair, with no known conflict.
TB-500compatible
Systemic recovery stack; no pharmacological interaction.
CJC-1295 (no DAC) and ipamorelincaution
Exogenous growth hormone suppresses the pituitary, so secretagogues have little to release while HGH is on board.
Insulin and diabetes medicationscaution
Growth hormone opposes insulin and raises glucose; doses of glucose lowering drugs may need adjusting under medical supervision.
Corticosteroidscaution
Glucocorticoids blunt the growth promoting effect of somatropin, and growth hormone can increase cortisol clearance.
Thyroid medicationcaution
Growth hormone increases conversion of T4 to T3 and can unmask hypothyroidism; thyroid labs should be rechecked.
Oral estrogencaution
Oral estrogen blunts liver IGF-1 production, so women on it may need a higher dose for the same IGF-1 response.
Adds direct IGF-1 signaling on top of the growth hormone driven liver IGF-1 for a stronger anabolic effect; increases hypoglycemia risk.
Common recovery pairing; growth hormone raises IGF-1 and collagen synthesis while BPC-157 targets local tissue repair.
Systemic recovery stack alongside growth hormone for injury rehabilitation.
Safety
- ▲Fluid retention, swollen hands and feet
- ▲Joint pain and stiffness
- ▲Carpal tunnel symptoms, tingling and numb fingers
- ▲Elevated blood glucose and reduced insulin sensitivity
- ▲Headache
- ▲Injection site pain, bruising, or fat loss at the site
- ▲Fluid retention, swollen hands and feet, joint pain, and carpal tunnel symptoms are dose related and very common above 2 IU daily.
- ▲Raises blood glucose and reduces insulin sensitivity; monitor fasting glucose and HbA1c, especially with prolonged use.
- ▲Suppresses your own growth hormone production while you use it, unlike secretagogues.
- ▲Chronically elevated IGF-1 is a theoretical cancer risk; do not use with any active or prior malignancy.
- ▲Counterfeit and underdosed product is rampant on the grey market; brand pens from pharmacies are the only reliable source.
- ■Fasting glucose or HbA1c rises into the prediabetic range
- ■Persistent carpal tunnel symptoms or joint swelling that do not resolve at a lower dose
- ■Severe headaches, vision changes, or nausea, which can signal raised intracranial pressure
- ■Any new lump, growth, or cancer diagnosis
- ■IGF-1 well above the age reference range on repeat testing
Community poll
Self-reported by visitors. Not clinical evidence.HGH (Somatropin): frequently asked
How much muscle will HGH build?
Less than most people think. In healthy adults it adds a few pounds of lean mass over months, and a good portion of that is water and connective tissue rather than contractile muscle. Strength does not improve in controlled studies. The fat loss and the fuller look are more reliable than the muscle gain.
What is a good starting dose?
Most people start at 1-2 IU daily and hold there for a few weeks before considering an increase. Side effects like tingling hands and water retention scale with dose, and 2 IU is plenty for recovery and skin benefits. Doses of 4 IU and up are body composition territory with a much higher side effect load.
Is a secretagogue like CJC-1295 and ipamorelin as good as HGH?
No. Secretagogues produce pulses of your own growth hormone and are limited by what your pituitary can release, which is why IGF-1 rises modestly. HGH delivers a set amount regardless. The secretagogues are cheaper, keep your own production intact, and have fewer side effects, but they are weaker.
How do I convert IU to mg?
The current standard is 3 IU per mg of somatropin, so a 10 IU vial holds about 3.33 mg and a 12 IU vial about 4 mg. Older references used slightly different factors, which is why you sometimes see conflicting numbers.
Does it cause diabetes?
It raises blood glucose and reduces insulin sensitivity while you are on it, and the effect is dose dependent. In people who are already prediabetic that can be enough to push them over. Regular bloodwork is not optional with sustained use.
References
- Effects of human growth hormone in men over 60 years old. New England Journal of Medicine, 1990
- Systematic review: the safety and efficacy of growth hormone in the healthy elderly. Annals of Internal Medicine, 2007
- The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial. Annals of Internal Medicine, 2010
- Consensus guidelines for the diagnosis and treatment of adults with growth hormone deficiency. European Journal of Endocrinology, 2007