HGH
Human Growth Hormone · Somatropin
Human Growth Hormone (HGH/Somatropin) is a 191-amino acid polypeptide hormone FDA-approved for pediatric and adult growth hormone deficiency, HIV-associated wasting, and other conditions. It provides both direct and indirect (IGF-1 mediated) anabolic effects.
Overview
Human Growth Hormone (HGH/Somatropin) is a 191-amino acid polypeptide hormone FDA-approved for pediatric and adult growth hormone deficiency, HIV-associated wasting, and other conditions. It provides both direct and indirect (IGF-1 mediated) anabolic effects.
Binds to GH receptors on target tissues, triggering JAK2-STAT5 signaling pathway. Direct effects include lipolysis, protein synthesis, and metabolic regulation. Indirect effects via IGF-1 promote growth and anabolism. Half-life ~3 hours subcutaneously.
Research indications
What the compound has been studied for, grouped by body system. Effect size is the reported magnitude where it was measured — not a recommendation.
FDA-approved for idiopathic and organic causes, Turner syndrome, Prader-Willi syndrome, SGA, Noonan syndrome, SHOX deficiency.
FDA-approved for childhood-onset or adult-onset causes (pituitary tumors, surgery, radiation, trauma).
FDA-approved to increase lean body mass and body weight in cachexia.
Significant fat loss especially abdominal/visceral fat over 1-3 months.
Increased muscle mass and improved body composition.
Enhanced exercise recovery and tissue healing.
Improved skin elasticity, texture, and hair/nail growth.
Improved energy, sleep, and quality of life.
A large effect in a weak study and a small effect in a strong one are different things. Effect size is never evidence of use in people.
- Class
- Single-chain polypeptide with two disulfide bridges
- Chain length
- 191 residues
- Molecular weight
- 22124 Da
- Half-life
- ~3.5 h
- Typical dose
- 1-4 IU daily (0.33-1.33mg); start low and titrate up
- Frequency
- Once daily or split into 2 doses (morning and evening)
- Cycle length
- 3-6+ months or ongoing for medical GHD
- Storage
- Lyophilized: Room temperature. Reconstituted: 2-8°C, use within 14-28 days
Molecular data
- Type
- Single-chain polypeptide with two disulfide bridges
- Molecular weight
- 22124 Da
- Chain length
- 191 residues
- Half-life
- 210 min
Dosing reference
Doses reported in the literature and by suppliers. These are a record of what has been used in research — reference, never instruction.
| Context | Route | Amount | Frequency |
|---|---|---|---|
| Medical GHD (Starting) | SubQ | 0.15-0.3mg/day (0.5-1 IU) | Once daily |
| Medical GHD (Maintenance) | SubQ | 0.4-0.8mg/day (1.2-2.4 IU) | Once daily |
| Anti-Aging/Wellness | SubQ | 1-2 IU/day (0.33-0.67mg) | Once daily |
| Body Recomposition | SubQ | 2-4 IU/day (0.67-1.33mg) | Once or twice daily |
| Performance (Higher Risk) | SubQ | 4-8 IU/day (1.33-2.67mg) | Split twice daily |
Interactions
HGH decreases insulin sensitivity; may require increased insulin doses in diabetics.
Synergistic but caution: enhanced effects with increased hypoglycemia and side effect risk.
Increases T4 to T3 conversion; unmasks hypothyroidism in 36-47% of patients.
GHRH analog can enhance effects though may be redundant with exogenous HGH.
Ghrelin mimetic works via different pathway.
Enhances natural pulsatile release.
Can unmask cortisol deficiency; replacement should precede HGH.
Commonly combined in hormone replacement therapy.
May manage insulin resistance; may reduce IGF-1 levels.
GLP-1 agonists help manage insulin resistance during HGH therapy.
Quality checklist
- ✓White to off-white lyophilized powder or solid cake (not liquid/collapsed)
- ✓Crystal clear reconstituted solution with no particles
- ✓Intact vacuum in sealed vial (resistance when inserting needle)
- ✓Pharmaceutical grade with certificate of analysis (Genotropin, Norditropin, Humatrope preferred)
- !Generic/underground lab products have highly variable quality and potency
- !Common counterfeits exist; third-party testing recommended
- ×Cloudy, discolored, or particles visible indicates degradation
- ×Powder appears melted or stuck to vial (improper storage)
- ×Yellow/brown coloring
What to expect
Safety
- Water retention and fluid accumulation
- Joint pain and stiffness
- Carpal tunnel syndrome (usually resolves with dose reduction)
- Headaches
- Numbness/tingling in hands
- Severe or worsening carpal tunnel symptoms
- Signs of diabetes (increased thirst, frequent urination, blurred vision)
- Severe edema (facial, hand, or feet swelling)
- Severe joint/muscle pain unresponsive to dose reduction
- New lumps, masses, or rapidly growing moles
- Severe headaches or vision changes
- Signs of allergic reaction
- Gynecomastia (breast tissue growth in males)
- Hypothyroid symptoms (fatigue, weight gain, cold intolerance)
- Active cancer (may accelerate tumor growth)
- Acute critical illness (increased mortality in ICU patients)
- Closed epiphyses in children (for growth promotion)
- Pregnancy/breastfeeding
FAQ
Will HGH unmask thyroid problems?
Yes. HGH unmasks central hypothyroidism in 36-47% of users by increasing T4-to-T3 conversion. Get baseline thyroid labs (TSH, free T4, free T3) before starting and recheck at 6-8 weeks. Many users need T4 supplementation while on HGH.
How much carpal tunnel syndrome should I expect from HGH?
Carpal tunnel symptoms are common (10-30% of users) and typically mild to moderate. They usually resolve with dose reduction. Symptoms typically peak at 2-4 weeks and improve as your body adapts. Starting low and titrating up reduces risk.
Does HGH require continuous use or can I cycle it?
HGH effects are dose-dependent and reversible. Most users cycle 3-6 months on, 1-2 months off to maintain sensitivity and allow recovery of natural GH production. Continuous use is possible but may increase side effect risk over time.
Can HGH cause diabetes?
HGH decreases insulin sensitivity, potentially unmasking pre-diabetes or causing diabetes in susceptible individuals. Monitor fasting glucose and HbA1c regularly. Those with family history of diabetes should proceed cautiously and may need metformin support.
References
- 1Unmasking of Central Hypothyroidism Following Growth Hormone Replacement in Adult Hypopituitary PatientsAgha A, Walker D, Perry L, et al. · Clinical Endocrinology · 2007
In 84 apparently euthyroid patients, 30 (36%) developed hypothyroidism requiring T4 therapy after starting GH. Highest risk in patients with organic pituitary disease or multiple pituitary hormone deficiencies.
human-pilotPubMed 17201804 ↗ - 2Efficacy and Safety of Growth Hormone Treatment in Adults with Growth Hormone Deficiency: A Systematic Review of Studies on MorbidityDefined a, Sääf M, et al. · Clinical Endocrinology · 2014
Systematic review demonstrating positive effects of GH treatment on cardiovascular disease and fracture risk, improvements in body composition, muscle strength, quality of life, bone mass/density, and lipoprotein patterns.
reviewPubMed 24750271 ↗ - 3Cardiovascular Risk in Growth Hormone Deficiency: Beneficial Effects of Growth Hormone Replacement TherapyGazzaruso C, Gola M, Karamouzis I, et al. · Endocrine · 2016
GH deficiency is associated with several cardiovascular risk factors that significantly increase cardiovascular morbidity and mortality. GH replacement improves cardiovascular risk factors.
reviewPubMed 27241971 ↗ - 4Long-term Safety of Growth Hormone in Adults With Growth Hormone Deficiency: Overview of 15,809 GH-Treated PatientsStochholm K, Kiess W, Gianetti E, et al. · Journal of Clinical Endocrinology & Metabolism · 2022
15,809 patients from the KIMS database, mean 5.3 years follow-up. Adverse events in 51.2% of patients, treatment-related in 18.8%. No correlation between GH dose and adverse event rate. Supports long-term safety of GH replacement in adults with GHD.
reviewPubMed 35368070 ↗