Human Growth Hormone (HGH, somatropin)

Growth hormone is like a central heating boiler. If yours is broken, getting a new one fitted by a professional transforms the house. If yours already works, fitting a second boiler mostly fogs up the windows: you get a bit more warmth on paper, a lot more condensation, and a bigger bill when something leaks.

Growth hormone binds the growth hormone receptor on liver, muscle, fat and bone cells, activating JAK2/STAT5 signalling. Much of its growth and anabolic effect comes from increased IGF-1, produced mainly by the liver. It also has direct effects: it breaks down stored fat (lipolysis), causes fluid and sodium retention, and opposes insulin, which raises blood glucose. In people who lack it, replacing it restores normal growth, body composition and wellbeing. In people who already make normal amounts, extra GH mainly shifts body composition (some fat lost, lean mass gained, partly as retained water) without clear gains in strength.

Research contexts. Not proven uses, and not recommendations.

Two stories. For its licensed uses, somatropin has decades of human trial evidence and is standard specialist care in the UK, with NICE guidance in place for adults since 2003. For the grey-market uses, the human evidence exists and is unflattering. In healthy older people, a systematic review of 18 randomised study populations (Liu 2007) found about 2.1 kg more lean mass and 2.1 kg less fat with no change in weight, alongside more swelling, joint pain, carpal tunnel syndrome and gynaecomastia and a trend towards diabetes. In fit young adults, a review of 27 randomised study samples (Liu 2008) found 2.1 kg more lean mass but no clear improvement in strength or exercise capacity. A 96-person randomised trial in recreational athletes (Meinhardt 2010) showed a small rise in sprint capacity that disappeared within 6 weeks of stopping, with no change in endurance, strength or power. Long-term follow-up of nearly 24,000 people treated as children (SAGhE) did not show a general rise in cancer but flagged some cancer signals that are still being investigated.

• !Fluid retention side effects are common in adults: swelling of the hands, feet and face, joint pain, muscle pain, stiffness and pins and needles, and they increase with dose.
• !Carpal tunnel syndrome and gynaecomastia (breast tissue growth in men) were more common in trials of GH in healthy older people.
• !GH opposes insulin and can raise blood glucose; type 2 diabetes is a listed side effect of the licensed medicine, and trials in healthy older people showed a trend towards new diabetes and impaired fasting glucose.
• !Cancer risk is not settled: GH raises IGF-1, and the large SAGhE study of people treated in childhood found unexplained signals for bone and bladder cancer and Hodgkin lymphoma, though no general carcinogenic effect.
• !Lean mass gains in healthy people are partly retained water, and trials have not shown clear gains in strength or endurance.
• !Grey-market "HGH 191aa" and generic "tropin" vials have no regulatory oversight: identity, strength, sterility and storage are unknown, and injecting non-sterile product risks infection.
• !It is a Class C controlled drug in the UK, and supplying it outside the medical system is a criminal offence.

Somatropin is a licensed prescription-only medicine (POM) in the UK, regulated by the MHRA. Brands include Genotropin (Pfizer; the Genotropin 2 mg MiniQuick SmPC, PL 00057/0998, gives first authorisation as 14 September 1998), Norditropin, Omnitrope, Humatrope and Saizen. Licensed uses are growth failure in children (growth hormone deficiency, Turner syndrome, chronic renal insufficiency, short children born small for gestational age, Prader-Willi syndrome) and replacement in adults with severe, confirmed growth hormone deficiency. NICE TA64 (2003) restricts NHS adult treatment to severe deficiency on testing plus impaired quality of life. It is not licensed for muscle building, fat loss or anti-ageing. Somatropin, somatotropin and somatrem are also Class C controlled drugs under Schedule 2 Part III of the Misuse of Drugs Act 1971, and sit in Schedule 4 Part II of the Misuse of Drugs Regulations 2001, alongside anabolic steroids. Possessing it in the form of a medicinal product is not an offence, but supplying it, possessing it with intent to supply, or producing it are offences (Class C supply and production carry up to 14 years). Grey-market "HGH 191aa" sold online is unlicensed and outside the legal supply chain.

• ACTRN012605000508673· Randomised, placebo-controlled trial· Completed (results published, Ann Intern Med 2010)

  Effects of growth hormone, alone or with testosterone, on body composition and performance in recreational athletes

  96 recreational athletes, 8 weeks; small temporary sprint gain, no change in endurance, strength or power.

1. 01
   Systematic review: the safety and efficacy of growth hormone in the healthy elderly — Liu H, Bravata DM, Olkin I, et al., Annals of Internal Medicine, 146(2):104-115 (2007)

   18 RCT populations, 220 GH-treated older adults; lean mass +2.1 kg, fat -2.1 kg, no weight change; more oedema, arthralgia, carpal tunnel syndrome and gynaecomastia. Concludes GH cannot be recommended as an anti-ageing therapy.

2. 02
   Systematic review: the effects of growth hormone on athletic performance — Liu H, Bravata DM, Olkin I, et al., Annals of Internal Medicine, 148(10):747-758 (2008)

   27 RCT samples, 303 GH-treated fit young adults; lean mass +2.1 kg but strength and exercise capacity did not appear to improve; more oedema and fatigue.

3. 03
   The effects of growth hormone on body composition and physical performance in recreational athletes: a randomized trial — Meinhardt U, Nelson AE, Hansen JL, et al., Annals of Internal Medicine, 152(9):568-577 (2010)

   96 recreational athletes, 8 weeks; lean mass gain via extracellular water; sprint capacity up 3.9% (lost 6 weeks after stopping); no change in endurance, strength or power. Funded by WADA.

4. 04
   Cancer Risks in Patients Treated With Growth Hormone in Childhood: The SAGhE European Cohort Study — Swerdlow AJ, Cooke R, Beckers D, et al., Journal of Clinical Endocrinology and Metabolism, 102(5):1661-1672 (2017)

   23,984 patients treated with recombinant GH; no general carcinogenic effect, but signals for bone and bladder cancer and Hodgkin lymphoma needing further investigation.

5. 05
   Genotropin 2mg MiniQuick - Summary of Product Characteristics (SmPC), electronic medicines compendium (emc), UK

   UK licensed indications, side effects (fluid retention, arthralgia, myalgia, paraesthesia, type 2 diabetes) and first authorisation date for this presentation (14 September 1998).

6. 06
   Human growth hormone (somatropin) in adults with growth hormone deficiency (TA64), National Institute for Health and Care Excellence (NICE) (2003)

   NHS criteria for adult GH treatment: severe deficiency on testing plus impaired quality of life.

7. 07
   Misuse of Drugs Act 1971, Schedule 2 (Part III, Class C), legislation.gov.uk

   Lists somatotropin, somatrem and somatropin as Class C drugs.

8. 08
   The Misuse of Drugs Regulations 2001, Schedule 4 (Part II), legislation.gov.uk

   Places somatotropin, somatrem and somatropin in Schedule 4 Part II with anabolic steroids.

9. 09
   Drugs penalties, GOV.UK

   Class C: supply and production carry up to 14 years in prison; possession of anabolic steroids for personal use is not an offence.

10. 10
    The 2026 Prohibited List (World Anti-Doping Code), World Anti-Doping Agency (2026)

    S2.2.3: growth hormone, its analogues and fragments, prohibited at all times. Wording checked against the official 2026 list text as republished in the Austrian Federal Law Gazette (BGBl. III Nr. 219/2025).