Somatropin (growth hormone)
Somatropin is a manufactured copy of human growth hormone. It is a prescription medicine for children and adults with growth hormone deficiency and for some other conditions that affect growth in children.
Reference information, not medical advice. Enhanced Training Studio doesn't sell, supply or recommend any substance. Doses are left out on purpose: only a prescriber can set one. How this library is written.
What it is
Somatropin is recombinant human growth hormone, a manufactured copy of the hormone made by the pituitary gland [1]. It is given by injection under the skin and is sold under several brand names. In the UK it is a prescription-only medicine, and treatment should be started and monitored by doctors experienced in growth disorders [2].
How it works
Growth hormone acts on many tissues. In children it stimulates growth of the long bones. It also raises blood levels of insulin-like growth factor 1 (IGF-1), which carries out many of its effects, and it changes body composition by reducing fat and increasing lean mass [1]. Somatropin can reduce the body's sensitivity to insulin and can increase the conversion of the thyroid hormone T4 to T3 [1, 2]. After injection under the skin its half-life is about 3 hours [1].
Approved medical uses
In children, somatropin is licensed for poor growth due to growth hormone deficiency, Turner syndrome, Prader-Willi syndrome, chronic kidney disease (UK) and children born small for gestational age, with some differences between products and countries; in the US it is also approved for idiopathic short stature [1, 2]. In adults, it is licensed as replacement therapy for confirmed, marked growth hormone deficiency that began in childhood or adulthood [1, 2]. It should only be used under specialist medical supervision.
What the research shows
- Adults with growth hormone deficiency: replacement changes body composition, lowering fat mass and increasing lean mass, which is the basis for its licensed use [1].
- Healthy older people: a systematic review of 18 randomised trials (508 participants) found small changes in body composition but more side effects, including swelling, joint pain, carpal tunnel syndrome and breast enlargement in men. The authors concluded it cannot be recommended as an anti-ageing treatment [3].
- Healthy, active adults: a systematic review found that growth hormone increased lean body mass but did not improve strength or exercise capacity, and it caused more fluid retention and fatigue. The authors concluded that claims of better physical performance are not supported by the evidence [4].
- The trials in these reviews were small, so the long-term effects of use outside licensed indications are not well known [3, 4].
Known risks and side effects
- Fluid retention and swelling, joint pain, muscle pain, tingling and carpal tunnel syndrome are common in adults [1].
- Reduced insulin sensitivity, raised blood sugar and new diabetes [1, 2].
- Raised pressure in the skull (intracranial hypertension), with headache and vision changes [1].
- Higher risk of a second tumour, especially meningioma, in people who survived childhood cancer; somatropin must not be used with active cancer [1, 2].
- In children: slipped upper femoral epiphysis (a hip problem) and worsening scoliosis [1].
- Pancreatitis has been reported rarely [1].
- It must not be used in people with acute critical illness, for example after open heart surgery. In studies of critically ill patients, death rates were 42% with somatropin compared with 19% with placebo [1].
- It must not be used in Prader-Willi syndrome with severe obesity or breathing problems because of reports of sudden death, or in active proliferative or severe non-proliferative diabetic retinopathy [1].
- Growth hormone is prohibited at all times in sport under the WADA Prohibited List [5].
Blood tests commonly monitored
- IGF-1, to guide treatment [1, 2].
- Blood glucose (and diabetes control in people with diabetes) [1, 2].
- Thyroid function, since somatropin can unmask or worsen an underactive thyroid [1, 2].
- Cortisol / adrenal function in people at risk of adrenal insufficiency [1].
- Eye examination (fundoscopy) if intracranial hypertension is suspected [1].
If you and your doctor are monitoring treatment, Enhanced Training Studio keeps a private log on your phone: what you take and when, your blood test results over time, and how you feel. How tracking works.
Sources
- Pfizer. Genotropin (somatropin) for injection: prescribing information. US Food and Drug Administration, revised 2025. FDA label (PDF)
- Pfizer. Genotropin powder and solvent for solution for injection: Summary of Product Characteristics. Electronic Medicines Compendium, updated 2024. eMC SmPC
- Liu H, Bravata DM, Olkin I, et al. Systematic review: the safety and efficacy of growth hormone in the healthy elderly. Annals of Internal Medicine, 2007. Annals of Internal Medicine
- Liu H, Bravata DM, Olkin I, et al. Systematic review: the effects of growth hormone on athletic performance. Annals of Internal Medicine, 2008. PubMed
- World Anti-Doping Agency. Prohibited List 2026, class S2: peptide hormones, growth factors, related substances and mimetics (English text as reproduced by the German Sport University Cologne). DSHS Cologne
Related
Last reviewed 7 October 2026. General information, not medical advice. Found a mistake? Email [email protected].