Recombinant human growth hormone (rhGH, somatropin) is a synthetic replica of the body's own pituitary growth hormone, used clinically to treat growth hormone deficiency, pediatric short stature, and HIV-related muscle wasting.
What it does
Somatropin is a lab-produced copy of the 191-amino acid protein your pituitary gland normally releases in pulses, primarily at night. It works by binding to growth hormone receptors on liver cells (hepatocytes) and tissues throughout the body, triggering the liver to produce IGF-1 (insulin-like growth factor 1) — the downstream hormone that drives most of growth hormone's anabolic, or tissue-building, effects.
The practical results of that signaling cascade are several: increased protein synthesis (building muscle tissue), lipolysis (the breakdown of stored fat, particularly visceral fat around the organs), improved bone mineral density, and enhanced wound healing. In children whose growth plates — the epiphyses, the soft cartilage zones at the ends of long bones — are still open, rhGH also drives linear height gain.
The tradeoff is metabolic: rhGH also impairs glucose uptake by peripheral tissues, meaning it pushes the body toward insulin resistance. This is a core feature of its mechanism, not a side effect to ignore.
What the evidence shows
Adult Growth Hormone Deficiency (GHD) Strong clinical evidence; FDA-approved indication with decades of controlled trial data
Adults with confirmed GHD — diagnosed via stimulation testing — show consistent improvements in body composition with rhGH: reduced visceral fat, increased lean mass, and better bone density. Long-term registry data also show quality-of-life improvements. This is the most evidence-supported use case in adults. Note: no specific citations were provided for this monograph, so study-level detail cannot be attributed here.
Pediatric Growth Failure Strong clinical evidence; FDA-approved across multiple etiologies including GHD, Turner syndrome, and idiopathic short stature
Pediatric rhGH use has the longest clinical track record of any indication. Children with GHD, Turner syndrome (a chromosomal condition causing short stature in females), Prader-Willi syndrome, and idiopathic short stature all show measurable height gains in randomized trials. The earlier treatment begins relative to bone maturation, the greater the effect on final adult height. No specific citations were provided for this monograph.
HIV-Associated Wasting Moderate clinical evidence; FDA-approved indication
At higher doses (1–2 mg/day), rhGH is approved to treat the muscle wasting and fat redistribution that can accompany HIV infection and antiretroviral therapy. Trials have shown improvements in lean body mass and functional capacity in this population. The higher doses used also carry higher rates of side effects, particularly edema and glucose dysregulation. No specific citations were provided for this monograph.
Off-label: Anti-aging / Body Composition in Healthy Adults Mixed human evidence; benefit-to-risk profile in healthy adults is not well established
rhGH is widely used off-label for fat loss and muscle gain in otherwise healthy people. Controlled trials in healthy older adults do show modest improvements in body composition, but gains in muscle strength and function are inconsistent, and side effects — particularly fluid retention, carpal tunnel syndrome, and insulin resistance — are more pronounced at higher doses. No long-term safety data exist for this use. The evidence does not clearly support routine use in healthy individuals, and regulatory bodies do not endorse it for this purpose. No specific citations were provided for this monograph.
How it's used
In studies and approved clinical protocols, doses for adult GHD range from 0.1 to 0.6 mg administered subcutaneously (injected under the skin) once daily. HIV-related wasting protocols use higher doses, typically 1–2 mg/day. Pediatric dosing is weight-based and managed by a physician. Injections are typically given in the evening to approximate the body's natural overnight growth hormone pulse. Intramuscular (IM) injection is an alternative route but subcutaneous is standard. Dose titration — starting low and adjusting based on IGF-1 blood levels and tolerability — is standard practice in clinical settings.
Side effects and safety
Mild side effects include injection site reactions, headache, muscle aches, and minor swelling. At moderate doses, carpal tunnel syndrome (nerve compression in the wrist causing tingling and weakness), joint pain, and meaningful fluid retention are reported with some frequency. Insulin resistance is a predictable metabolic consequence of the mechanism itself, not a rare adverse event — blood glucose should be monitored.
Serious but less common risks include intracranial hypertension (increased pressure in the skull, presenting as severe headache and vision changes), pancreatitis, and in pediatric patients, slipped capital femoral epiphysis (the ball of the hip joint displacing from the thigh bone) and worsening scoliosis.
rhGH is absolutely contraindicated in anyone with an active cancer diagnosis, critical illness from surgery or trauma, proliferative diabetic retinopathy (advanced eye damage from diabetes), or pregnancy. It requires caution in people with diabetes, obesity, sleep apnea, or a history of intracranial pressure issues.
Long-term safety in off-label use by healthy adults — particularly the question of cancer risk given that IGF-1 promotes cell growth — remains genuinely unresolved. The concern is biologically plausible; the data are not yet conclusive.
Bottom line
Recombinant human growth hormone has a well-established, decades-long track record in its approved indications — growth hormone deficiency, pediatric growth failure, and HIV wasting — where the benefit-to-risk math is clear. For healthy adults seeking body composition changes, the evidence is thinner and the metabolic risks (insulin resistance, fluid retention, long-term IGF-1 exposure) are real enough to take seriously. This is a prescription-only medication with meaningful contraindications, not a wellness supplement.