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HGH (Somatropin)31 residues (approx.)FPTIPLSRLFDNAMLRAHRLHQLAFDTYQEFEach bubble = one amino acid. Size = residue mass. Color = chemical class.Uses closest standard amino acids for non-standard residues.Also known as: HGH, rhGH, recombinant human growth hormone
Rudman's 1990 trial put it on the map: 8.8% more lean mass and 14.4% less body fat in six months of daily injections. Somatropin (HGH) is a 191-amino-acid recombinant protein identical to the growth hormone your pituitary gland produces. It carries FDA approval for pediatric and adult growth hormone deficiency, Turner syndrome, and HIV-associated wasting. The KIMS database tracked 15,809 treated adults and confirmed a favorable long-term safety profile at therapeutic doses. Cost is the barrier. Pharma-grade runs $750 to $2,000+ per month. Anti-aging users typically settle on 1 to 2 IU daily for sleep, skin, and gradual body recomposition.
The Rudman study changed how the world thinks about aging. In 1990, a six-month trial gave recombinant growth hormone to men over 60 and tracked an 8.8% increase in lean body mass with a 14.4% decrease in adipose tissue (NEJM)[1]. That single paper launched three decades of research into somatropin. Somatropin (brand names Genotropin, Humatrope, Norditropin, Omnitrope) is a 191-amino-acid protein produced via recombinant DNA technology. It's identical to endogenous human growth hormone. Unlike secretagogues that stimulate your pituitary to release GH, somatropin is the hormone itself. Subcutaneous injection delivers roughly 80% bioavailability with peak serum levels at 3 to 5 hours and a terminal half-life of about 2.5 hours. The biological effects, mediated through IGF-1, persist 20 to 24 hours. The FDA has approved somatropin for pediatric GHD, adult GHD, Turner syndrome, chronic kidney disease, Prader-Willi syndrome, and HIV-associated wasting. Off-label use centers on anti-aging (1 to 2 IU daily), body recomposition (2 to 4 IU), and athletic performance (4 to 6 IU). Sleep quality improvement is the first thing users notice, often within the first two weeks. The KIMS database, tracking 15,809 GH-treated adults, confirmed neutral effects on lipids and glucose at appropriate doses and found no increased malignant cancer incidence [2]. A 2025 Frontiers in Aging meta-analysis of RCTs confirmed lean mass gains and fat loss but found no statistically significant strength improvements at 3 to 12 months [3]. Insulin resistance remains the side effect that demands the most monitoring.
Somatropin binds to the growth hormone receptor (GHR), a transmembrane receptor that sits as a preformed dimer on cell surfaces. Binding triggers a conformational change that activates Janus Kinase 2 (JAK2), a tyrosine kinase physically linked to the receptor's intracellular domain. JAK2 phosphorylates tyrosine residues on the GHR itself, creating docking sites for STAT proteins. STAT5b is the primary downstream signal. Once recruited and phosphorylated by JAK2, STAT5b dimerizes and translocates to the nucleus. There it drives transcription of target genes. The most important product is IGF-1 (insulin-like growth factor 1), produced mainly by the liver; IGF-1 mediates most of somatropin's anabolic effects. Protein synthesis accelerates. Cell proliferation increases. Apoptosis slows. Two additional pathways matter. The MAPK/ERK pathway promotes cell growth and differentiation. The PI3K/Akt pathway regulates glucose metabolism and cell survival, which partly explains why somatropin antagonizes insulin signaling at higher doses. Somatropin's direct lipolytic action operates through a separate mechanism that doesn't involve IGF-1 at all. Hormone-sensitive lipase activation in adipocytes breaks down stored triglycerides. This is why fat loss, particularly visceral fat, is one of the most consistent and dose-dependent effects. The dual mechanism (IGF-1-mediated anabolism plus direct lipolysis) is what makes somatropin effective for body recomposition.
Strong evidence for body composition improvements (lean mass, fat loss) and bone density in GH-deficient adults. Moderate evidence for general anti-aging and wellness use in healthy older adults: 6-month trials show +4.3% lean mass / -13.1% fat mass, but long-term safety in non-GHD populations remains unresolved. No statistically significant improvements in muscle strength in RCT meta-analyses at 3-12 months.
Rudman et al. NEJM 1990 (PMID 2355952): foundational 6-month RCT; KIMS database 15,809 patients long-term safety; Frontiers in Aging 2025 review (PMID 40260058): meta-analysis of RCTs: significant lean mass gain and fat loss, no significant strength gain at 3–12 months
Most RCTs ≤12 months in duration; anti-aging use in healthy adults lacks dedicated long-term RCTs; 2024 Swedish childhood cohort (n=53,444, 19.8-year follow-up) found HR 1.28 for benign neoplasms but no increase in malignant cancer risk; no 2024–2026 RCT specifically studying 1–2 IU/day in healthy aging adults
Widely trusted as the gold standard for body recomposition and anti-aging. Pharma-grade is universally respected for purity; grey market quality is the primary controversy. Anti-aging community considers 1–2 IU/day a conservative, sustainable protocol; bodybuilding community uses 4–6 IU/day with AAS.
Science and community agree on body composition benefits (lean mass gain, fat loss). Diverge on: (1) dose thresholds: community anti-aging doses (1–2 IU) sit above FDA-recommended GHD starting doses (0.3–0.6 IU) but below most trial doses; (2) indication: community uses predominantly for off-label anti-aging/performance, which FDA prohibits; (3) muscle strength: community reports improved performance but RCT meta-analyses show no statistically significant strength gains at ≤12 months.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 1 IU | Daily |
| Moderate | 3 IU | Daily |
| Aggressive | 6 IU | Daily |
Somatropin is dosed in IU, not mcg. One IU equals roughly 0.33 mg. That conversion trips people up initially. If you're using a lyophilized vial (not a pre-filled pen), reconstitute with bacteriostatic water. For a 10 IU vial with 1 mL of BAC water, each 10 units on an insulin syringe equals 1 IU. A 1 IU daily dose means drawing to the 10-unit mark. At 2 IU, draw to 20 units. At 0.5 IU for the ramp-in phase, that's 5 units on the syringe. Pre-filled pens (Norditropin FlexPro, Genotropin GoQuick) skip this math entirely. Dial the dose and inject. Inject on an empty stomach. Carbohydrates blunt GH action. Morning fasted or pre-bed are the two most common timing windows. Splitting the dose (AM plus pre-bed) becomes relevant above 3 IU daily. Store reconstituted vials at 2 to 8 degrees Celsius. Above that temperature, somatropin denatures within days. A vial that sat on your counter overnight may still look fine but test like a counterfeit. IGF-1 labs every three months. That's the number that tells you whether your dose is working and whether it's too high.
For anti-aging doses (1-2 IU), many practitioners run continuously with periodic IGF-1 monitoring rather than cycling. At higher doses (4+ IU), 6 months on / 1 month off helps maintain insulin sensitivity. Some protocols use 5 days on, 2 days off weekly to reduce cost and manage sides.
Exogenous HGH suppresses endogenous pituitary GH secretion via IGF-1 negative feedback and somatostatin upregulation. Extended continuous use can reduce pituitary GH response capacity: though the clinical significance varies by dose and duration. At therapeutic doses (1–2 IU/day), many practitioners run continuously with periodic IGF-1 monitoring rather than strict cycling. At higher doses (4+ IU/day), 6 months on / 4–8 weeks off is standard practice to allow IGF-1 normalization, insulin sensitivity recovery, and pituitary axis reassessment. The 5 days on / 2 days off weekly schedule is a popular cost-reduction strategy with community reports of similar efficacy.
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Expected: Improved sleep quality (weeks 1–2), skin texture (months 2–4), mild fat redistribution (months 3–6); modest lean mass gains over 6+ months; significant muscle hypertrophy not expected at this dose
Monitor: IGF-1 at baseline and every 3 months; fasting glucose and HbA1c every 3–6 months; TSH at baseline
Set out your vial, bacteriostatic water, alcohol swabs, and a 29 to 31 gauge insulin syringe (0.5 mL or 1 mL).
If using a lyophilized vial for the first time, reconstitute by drawing 1 mL of bacteriostatic water into the syringe. Inject slowly along the vial wall. Never shake the vial; swirl gently until the powder dissolves completely.
With a 10 IU vial reconstituted in 1 mL BAC water, each 10 units on a 100-unit insulin syringe equals 1 IU. For a 30 IU vial in 1 mL, each 3.3 units equals 1 IU; for a 36 IU vial in 1 mL, each 2.8 units equals 1 IU.
Draw the appropriate number of units. Remove air bubbles by tapping and slowly pushing the plunger until a tiny drop appears at the needle tip.
Choose an injection site: abdomen (2 inches from the navel), outer thigh, or upper arm. Clean the site with an alcohol swab.
Pinch a fold of skin and insert the needle at a 45 to 90 degree angle. Inject slowly. Hold for 5 seconds before withdrawing.
Rotate injection sites with each dose to prevent lipodystrophy.
Timing: inject fasted (30 to 60 minutes before food) in the morning for fat loss protocols. Pre-bed injection mimics natural circadian GH release and is preferred for sleep-focused or FDA-labeled GHD protocols. Above 3 IU daily, split into AM fasted plus pre-bed.
Store reconstituted vial in the refrigerator at 2 to 8 degrees Celsius. Use within 14 to 28 days depending on brand. Never freeze.
Reference standard; ~80% bioavailability. Inject into abdomen, thigh, or upper arm.
Rotate sites to prevent lipodystrophy. Peak serum GH at 3–5 hours. Insulin syringes (29–31G) are standard. Pre-filled pens (Norditropin FlexPro, Genotropin GoQuick) require no reconstitution.
Faster absorption than SC; peak slightly earlier (1–2 hours). Bioavailability similar. No dose adjustment needed.
Used clinically in some pediatric protocols. More painful for daily injections. No evidence of superior efficacy over SC for adult use. SC is universally preferred for self-administration.
Immediate but very short-lived peak; pharmacokinetically inferior for therapeutic use
IV route is used only for GH stimulation testing (GHRH + arginine test) under clinical supervision. Not appropriate for therapeutic or off-label protocols.
HGH drives endogenous IGF-1 production; exogenous IGF-1 LR3 adds direct anabolic signaling. Advanced body recomposition/hypertrophy stack. High-risk combination.
40–80 mcg IGF-1 LR3 SC, 5 days on/2 days off, post-workout
GHRH analog approved for HIV-associated lipodystrophy; sometimes stacked with low-dose HGH at clinics for visceral fat reduction. May be redundant when running full HGH: occasionally substituted on off-weeks for cost savings.
2 mg/day SC tesamorelin on HGH off-days
Cost-saving substitute for HGH on weekends (5 on/2 off strategy). Stimulates endogenous GH release on off-days to maintain GH pulse continuity.
200–300 mcg SC pre-bed on HGH off-days
Stacked on HGH off-days or weeks to sustain GH axis stimulation at lower cost. Do NOT run high-dose secretagogues simultaneously with high-dose HGH: creates supraphysiological GH levels.
CJC-1295 no-DAC 100–200 mcg + Ipamorelin 100–200 mcg SC, pre-bed, on HGH off-days only
Oral estrogen significantly reduces hepatic IGF-1 production in response to GH: women on oral HRT or oral contraceptives may require 2–3x higher HGH doses to achieve equivalent IGF-1 response. Transdermal estrogen has substantially less impact. Not dangerous but severely reduces efficacy.
Glucocorticoids attenuate GH growth-promoting effects and impair IGF-1 signaling. HGH may reduce 11β-HSD1 activity, altering cortisol conversion; in adrenal insufficiency patients on replacement therapy, HGH can unmask adrenocortical insufficiency requiring glucocorticoid dose adjustment. Monitor carefully.
Somatostatin directly opposes GH release and partially blocks GH receptor signaling. Completely negates benefits from HGH or any secretagogue. Used clinically to treat acromegaly: the opposite application.
Do not combineThe HGH + insulin "bodybuilding stack" creates severe hypoglycemia risk. HGH raises blood glucose (insulin resistance); exogenous insulin lowers it. Miscalculation can be fatal. Requires continuous glucose monitoring. Community labels this as advanced-only with experience and CGM.
Do not combinePricing updated 2026-04-09
Insulin resistance is the side effect that requires the most attention. Somatropin directly antagonizes insulin's action on glucose uptake. At doses above 2 IU daily, fasting blood glucose begins trending upward in many users. This can unmask pre-diabetes or worsen existing glycemic control. HbA1c should be checked every three to six months. Fasting glucose above 126 mg/dL is a clear signal to reduce the dose or pause the protocol. Peripheral edema is the most common complaint by volume. Swelling in the hands and feet affects up to 45% of patients at higher doses. It's fluid retention, not inflammation. The body adjusts within a few weeks for most people. If pitting edema develops or swelling involves the face and neck, other causes should be investigated. Carpal tunnel syndrome appears in 1 to 10% of users. Fluid retention compresses the median nerve, producing wrist tingling and hand numbness. This is the most frequent reason for dose reduction in community reports. Reducing by 0.5 IU daily and holding for two to four weeks typically resolves it. Almost always reversible. Joint pain and muscle stiffness affect roughly 20% of users, concentrated in the first few weeks. Both track with dose; both tend to settle as the body acclimates. Gynecomastia is rare but possible, particularly in men using higher doses. At doses above 4 IU daily for extended periods, some users report jaw growth and increased shoe size. These are signs of acromegaly-like effects from prolonged supraphysiological IGF-1 levels. Cancer risk generates the most anxiety. The KIMS database (15,809 patients) found no increased malignant cancer incidence at therapeutic doses. A 2024 Swedish childhood cohort (n=53,444, 19.8-year follow-up) found a hazard ratio of 1.28 for benign neoplasms but no increase in malignant tumors. Active malignancy remains a strict contraindication because GH and IGF-1 can promote tumor growth in existing cancers. Injection site reactions (redness, mild pain) are standard for subcutaneous administration. Rotating sites prevents lipodystrophy over long-term use. GH can unmask central hypothyroidism by increasing T4-to-T3 conversion. Monitor TSH and free T4, especially if IGF-1 levels aren't responding as expected. Hypothyroidism itself blunts the IGF-1 response. When to seek medical attention: persistent carpal tunnel after dose reduction, fasting glucose consistently above 110 mg/dL, visible changes in facial bone structure or extremity growth, or unexplained rapid weight gain with edema. Contraindications include active malignancy, active proliferative diabetic retinopathy, acute critical illness, Prader-Willi syndrome with severe obesity (pediatric), and pregnancy or breastfeeding. Known hypersensitivity to somatropin or excipients rules out use entirely.
Verify HGH (Somatropin) dosing and safety with a second opinion
Pharma-grade (Norditropin, Genotropin, Omnitrope) is a Schedule III controlled substance requiring a prescription: prohibitively expensive off-label ($1,000–$2,000+/month). Grey market Chinese kits (Ansomone, Jintropin, Hygetropin) dominate off-label use but carry significant quality risks: community widely reports underdosing (10 IU Chinese kits reportedly act like 5–6 IU pharma), lot-to-lot variability, counterfeit risk, and potential harmful fillers. Compounded HGH from 503A pharmacies is legal with a valid prescription but requires confirming the compounding pharmacy's license.
| Test | When | Target |
|---|---|---|
| IGF-1 (serum) | Baseline, then every 3 months during active protocol | 200–300 ng/mL for anti-aging doses; 150–400 ng/mL (age-adjusted mid-normal) for GHD treatment |
| Fasting blood glucose | Baseline, monthly for first 3 months, then every 3 months | <100 mg/dL fasting (normal range); >126 mg/dL = dose reduction required |
| HbA1c | Baseline, then every 3–6 months | <5.7% (normal); 5.7–6.4% = caution zone; >6.5% = action required |
| TSH and free T4 | Baseline, then every 6–12 months | TSH 0.4–4.0 mIU/L; free T4 0.9–1.7 ng/dL |
| Lipid panel (total cholesterol, LDL, HDL, triglycerides) | Baseline, then every 6 months | — |
| DEXA scan (bone mineral density + body composition) | Baseline, then annually | — |
Primary efficacy and safety marker. HGH dose-dependently raises IGF-1; supraphysiological IGF-1 associated with cancer risk and acromegaly.
HGH antagonizes insulin signaling; insulin resistance develops dose-dependently. Fasting glucose >100 mg/dL warrants dose adjustment.
Long-term glycemic impact marker. HbA1c >6.5% (diabetes threshold) in context of HGH use requires significant dose reduction or protocol pause.
GH can unmask central (secondary) hypothyroidism by increasing T4-to-T3 conversion rate. Undiagnosed hypothyroidism also blunts IGF-1 response to HGH.
GH deficiency is associated with dyslipidemia; HGH replacement typically improves lipid profile. Monitor for unexpected adverse effects at off-label doses.
Quantifies actual body recomposition (fat mass, lean mass) and bone density improvements: the primary long-term benefits of HGH therapy.
Better sleep quality is usually the first noticeable effect. Mild water retention and joint stiffness may appear as the body adjusts.
Skin starts looking fuller and more hydrated. Energy levels improve. Recovery from workouts is noticeably faster.
Measurable fat loss begins, especially visceral fat. Lean mass increases become apparent. Nails and hair grow faster.
Significant body recomposition. Rudman's study showed 8.8% lean mass increase and 14.4% fat reduction at 6 months. Bone density improvements begin.
Full benefits realized. Bone mineral density measurably improved on DEXA. Lipid profile improvements stabilize. Skin elasticity at peak improvement.
Weeks 1 to 2 (Sleep and Water): GH begins raising IGF-1 within 24 to 48 hours of the first injection. Sleep quality is the earliest benefit most users notice, often described as deeper and more restorative with vivid dreams. Mild water retention in the hands and feet is common. Morning joint stiffness may appear. Injection site redness is typical and usually minor. Weeks 3 to 6 (Skin and Recovery): IGF-1 reaches a new steady state around week four. Skin starts looking fuller and more hydrated. Workout recovery speeds up noticeably. Energy improves. Water retention typically stabilizes or resolves by this point. Carpal tunnel symptoms (wrist tingling, hand numbness) may surface; this is the first natural point for a dose adjustment if needed. Weeks 6 to 12 (Recomposition Begins): Body composition changes become detectable by DEXA. Visible fat loss begins, particularly around the abdomen. Lean mass improvements become apparent. Nails and hair grow faster. Side effects are generally stable and manageable by week eight if the dose has been adjusted appropriately. Months 3 to 6 (Peak Recomposition): This is the window where the Rudman benchmarks apply: 8.8% lean body mass gain and 14.4% fat mass reduction at the six-month mark (at roughly 2 IU daily average). Most community users describe this as the period where results become obvious. Skin improvement peaks. Recovery speed is markedly different from baseline. Glucose management becomes the most important safety consideration; an HbA1c check is recommended at the three-month mark. Months 6 to 12 (Bone and Metabolic Benefits): Bone mineral density improvement becomes measurable on DEXA after sustained therapy. Lipid profile effects stabilize. Long-term safety data from the KIMS database is reassuring at therapeutic doses. Benefits plateau unless the dose is maintained. Most users who cycle off at six months report noticeable washout within four to eight weeks, which confirms the physiological effect rather than placebo.
GH begins elevating IGF-1 within 24–48 hours; fluid retention and insulin resistance begin at the cellular level
Improved deep sleep (vivid dreams, more restorative): most consistent early effect. Mild water retention in hands and feet. Some report morning joint stiffness.
IGF-1 at new steady state by week 4; collagen synthesis and lipolysis rate changes measurable but not yet visually apparent
Skin looks fuller and more hydrated. Workout recovery noticeably faster. Energy improvement. Water retention often stabilizes or resolves. Carpal tunnel may emerge: first dose-adjustment point.
Measurable changes in body composition detectable by DEXA; fat mass reduction and lean mass accrual statistically significant in 6-month trials by this stage
Visible fat loss begins, especially visceral/abdominal. Lean mass improvements apparent. Nails and hair growing faster. Skin elasticity clearly improved for most users.
Rudman 1990 benchmarks: +8.8% lean body mass, -14.4% fat mass at 6 months (2 IU average). Bone density improvements begin but require 12+ months for full effect.
Significant body recomposition visible. Most report this as the best period. Skin at peak improvement. Recovery speed markedly different from pre-protocol baseline.
Bone mineral density measurably improved on DEXA (6-year study: +15.9% lumbar spine at mean 2.4 IU/day). Lipid profile improvements stabilize. Long-term cancer risk data reassuring at therapeutic doses per KIMS.
Benefits plateau unless dose is maintained. Most users cycle off at 6 months and report significant washout within 4–8 weeks: confirms real physiological effect rather than placebo.
Source: Norditropin FDA label Section 12.3: SC t½ 2-3 hours (mean ~2.5h); Genotropin label reports 3.0h in GHD adults
Loading the interactive decay curve.
Somatropin is FDA-approved and has been since 1985. Current approved brands include Norditropin (Novo Nordisk), Genotropin (Pfizer), Humatrope (Lilly), and Omnitrope (Sandoz, the only US biosimilar). It is classified as a Schedule III controlled substance under the Anabolic Steroids Control Act. A prescription is required for all legal use. Approved indications include pediatric and adult GHD, Turner syndrome, chronic kidney disease in children, Prader-Willi syndrome, and HIV-associated wasting. Off-label prescribing for anti-aging is legal at the prescriber's discretion but remains controversial. Compounded somatropin is available through 503A-licensed compounding pharmacies with a valid prescription. Verify that any compounding pharmacy holds current FDA registration. Somatropin is prohibited by the World Anti-Doping Agency (WADA) at all times, both in-competition and out-of-competition. Athletes subject to testing should be aware that recombinant GH detection methods have improved considerably since 2012. Grey market (non-prescription) HGH carries legal risk and quality concerns. Distribution of HGH for anti-aging purposes was specifically restricted by the 1990 amendments to the Food, Drug, and Cosmetic Act. This content is for educational and research purposes only. It does not constitute medical advice.
Peptide Schedule Research TeamReviewed Apr 20266 Citations
