Somatropin (HGH)

Somatropin is a lab-made copy of human growth hormone (recombinant human growth hormone, or rhGH) — the same hormone your pituitary gland (a small gland at the base of the brain) makes on its own. It’s a protein hormone, not an anabolic steroid and not a small-molecule “research chemical,” and it’s a real FDA-approved medicine for several conditions. Outside of those medical uses, it gets heavily marketed for anti-aging, fat loss, and athletic performance — but the best careful studies show it does far less than its reputation suggests, and selling it for those non-medical uses is a federal felony.

What it is

Somatropin is a single chain of 191 amino acids (the building blocks that make up proteins), weighing about 22 kDa (kilodaltons, a unit of molecular weight). Its sequence is an exact match for the main form of growth hormone your own body makes. It’s manufactured inside genetically engineered cells (often E. coli bacteria; some products use mammalian cells). An early, related product called somatrem (Protropin) had 192 amino acids instead, with an added methionyl unit.

Because it’s a protein hormone, somatropin has to be given by injection — either subcutaneous (under the skin) or intramuscular (into a muscle). It is not orally bioavailable as an intact protein, meaning your gut would simply digest it like food before it could work. So there’s no such thing as legitimate oral HGH, and the whole “oral versus injectable ester” debate that comes up with anabolic steroids has nothing to do with growth hormone. Somatropin doesn’t act on the androgen receptor (the docking site steroids use), it isn’t 17-alpha-alkylated (a chemical tweak used to make oral steroids survive the liver), and under US law it isn’t an anabolic steroid at all.

Here’s how it works. GH attaches to the growth hormone receptor (GHR), a protein that sits in the cell membrane and belongs to the cytokine-receptor family. That sets off an internal signaling chain known as JAK2/STAT5. A lot of GH’s muscle-building and growth effects don’t happen directly — instead, GH prompts the liver and local tissues to make another hormone called insulin-like growth factor 1 (IGF-1), which does much of the work. GH also has some direct effects of its own: lipolysis (breaking down fat), fluid retention, and an anti-insulin (diabetogenic, meaning it pushes blood sugar up) effect on how the body handles glucose. It helps the body build protein, lengthens bones in kids whose growth plates are still open, and plays a role in how the body handles fats, carbohydrates, and minerals.

The claims

GH has real, FDA-approved medical uses. In children, it’s approved for GH deficiency, Turner syndrome, Prader-Willi syndrome, Noonan syndrome, SHOX deficiency, chronic kidney problems (chronic renal insufficiency/pre-transplant), being born small for gestational age without catching up in growth, and idiopathic short stature (being unusually short with no clear cause). In adults, it’s approved for adult GH deficiency, HIV-associated wasting/cachexia (the wasting away of muscle and weight; brand Serostim), and short bowel syndrome (brand Zorbtive, which was FDA-approved for this use though it’s since been pulled from the market).

Separately, GH is promoted — without any approval — for anti-aging and “wellness,” for body recomposition (more muscle, less fat), and for athletic or strength performance. None of these are approved uses, and the evidence behind them is weak.

What the evidence actually shows

True GH deficiency (children and adults): strong, well-established benefit. Deficient children grow taller, and deficient adults see better body composition, stronger bones, and improved quality-of-life measures. This is the core use that’s actually backed by evidence — and the reason the drug exists in the first place.

Body composition in healthy or older adults: The famous Rudman et al. trial (NEJM, 1990; 21 men aged 61-81, 12 treated and 9 controls, over 6 months) found that GH increased lean body mass by about 8.8% and cut fat (adipose-tissue) mass by about 14.4%. That single result kicked off the whole modern “anti-aging GH” industry. But here’s the catch: that trial never measured or showed any gain in actual strength or physical function, and later research found that the shift in body composition doesn’t translate into meaningful strength or function.

The bigger-picture review in healthy older people: Liu et al. (Annals of Internal Medicine, 2007; ~220 participants, mean age ~69) pulled together the evidence and found GH produced only small drops in fat and small gains in lean mass — roughly 2 kg of each, with no net change in overall weight — and no proven improvement in strength, aerobic capacity, or any other outcome that actually matters in daily life. On top of that, side effects went up significantly: soft-tissue swelling (edema), joint pain, carpal tunnel syndrome, gynecomastia (breast tissue growth), and higher rates of impaired fasting glucose and diabetes. The authors concluded that GH can’t be recommended as an anti-aging therapy.

Athletes and strength: Much of the “lean mass” GH adds is actually fluid retention (extra water held outside the cells), not working muscle. Controlled studies don’t show better muscle strength, power, or sport-relevant performance in healthy or athletic adults. Aerobic capacity may not improve at all, and the swelling and fatigue can actually make it worse. In short, GH’s reputation as a performance booster runs well ahead of what the evidence supports.

Legal and regulatory status

HGH is not a controlled substance under the Controlled Substances Act, and it is not an anabolic steroid. (Anabolic steroids are Schedule III drugs under the Anabolic Steroid Control Act — a separate category that doesn’t include GH.)

Instead, HGH has its own dedicated criminal law: 21 U.S.C. § 333(e). It’s a felony to knowingly distribute HGH, or to possess it with intent to distribute, for any human use other than treating a disease or recognized medical condition that’s been authorized by the Secretary of HHS and ordered by a physician. The statute defines “human growth hormone” as somatrem, somatropin, or an analogue (a close chemical relative) of either. So handing it out for anti-aging, athletic performance, or bodybuilding is illegal. Penalties run up to 5 years in prison (up to 10 years if the offense involves someone under 18). A conviction is treated as a felony violation of the Controlled Substances Act for the purpose of seizing assets (forfeiture), and the DEA is authorized to investigate these cases.

In sport, growth hormone is banned at all times — both in and out of competition — under WADA Section S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). S2 also covers IGF-1, EPO/ESAs (drugs that boost red blood cells), GH-releasing peptides and secretagogues (compounds that nudge the body to make more GH — such as the GHRPs, ipamorelin, CJC-1295, and MK-677), and GH fragments such as AOD-9604. This is unchanged on the 2026 Prohibited List, in force since January 1, 2026. (Anabolic agents are listed under S1, not S2 — a common point of confusion; GH and its related growth factors sit in S2.)

Safety

GH’s risks are a different set from the ones that come with anabolic steroids. Several harms that people lump together as “performance drug” side effects — liver injury from 17-alpha-alkylation, shutting down the body’s testosterone production, virilization (developing male traits), androgenic gynecomastia, and polycythemia (too many red blood cells) — are anabolic-steroid effects and do not apply to GH. They’re listed here only to keep the picture honest.

• Fluid retention and swelling (edema), joint pain (arthralgias), muscle pain (myalgias), and carpal tunnel syndrome — the most common side effects, and they get worse with higher doses.
• Blood sugar: GH is diabetogenic, meaning it pushes blood sugar up. It causes insulin resistance and can lead to impaired fasting glucose or new-onset type 2 diabetes — a real worry for older or at-risk people.
• Acromegaly-like features with long-term excess or above-normal (supraphysiologic) doses: overgrowth of soft tissue and bone (hands, feet, jaw, and a coarsening of the face), enlarged organs (organomegaly), and an enlarged, thickened heart (cardiac hypertrophy/cardiomyopathy).
• Heart and blood vessels: acromegaly and long-term GH excess are linked to an enlarged heart, high blood pressure, and more cardiovascular disease. The harm from GH excess shows up mainly in the structure of the heart and in blood-sugar and metabolic changes, rather than the cholesterol shifts you see with oral anabolic steroids.
• Cancer and mortality signals: GH drives up IGF-1, which raises a theoretical worry about feeding tumor growth. The FDA put out a Drug Safety Communication in 2010 reviewing a possible mortality signal in the French SAGhE data (patients treated for short stature in childhood), then issued an August 2011 update concluding the evidence was inconclusive — partly because of how the study was designed and partly because no similar signal turned up anywhere else. The concern is still worth caution, especially with non-medical use.
• Risks specific to children: raised pressure inside the skull (intracranial hypertension), a hip-joint problem called slipped capital femoral epiphysis, and worsening scoliosis (curving of the spine). GH should not be used in active cancer, in certain Prader-Willi patients with severe obesity or breathing problems (deaths have been reported), or in acute critical illness (ICU trials showed higher death rates).
• Prion risk is a thing of the past — it applied to cadaver-derived GH, not to the recombinant somatropin made today.
• Black-market product risk: counterfeit or unregulated “HGH” is often underdosed, mislabeled, or non-sterile, piling infection and contaminant risk on top of everything above.

Bottom line

Somatropin is a genuinely FDA-approved recombinant growth hormone with strong evidence behind it in true GH deficiency and specific childhood and wasting conditions. But for healthy adults, older people, and athletes, the best controlled evidence (Liu 2007, plus the lack of any functional benefit in the Rudman-era and later work) shows only small body-composition changes, no proven gain in function, strength, or performance, and a meaningful load of side effects. Selling it for non-medical use is a federal felony under 21 U.S.C. § 333(e), and GH is banned at all times in sport under WADA S2.

Evidence grade: 10/10 · Established.

This grade reflects the quality of the underlying human evidence — which is strong in both directions: strong support for a real benefit in genuine GH deficiency and the approved medical conditions, and strong, well-controlled evidence that the popular anti-aging and performance uses don’t deliver any meaningful functional benefit.

Sources

• FDA Drug Safety Communication — Ongoing safety review of recombinant human growth hormone (somatropin)
• FDA Drug Safety Communication — Safety review update (August 2011)
• Norditropin (somatropin) FDA label (PDF)
• Omnitrope (somatropin) FDA label (PDF)
• Rudman D, et al. Effects of Human Growth Hormone in Men over 60 Years Old. N Engl J Med. 1990 (PMID 2355952)
• Liu H, et al. Systematic Review: The Safety and Efficacy of Growth Hormone in the Healthy Elderly. Ann Intern Med. 2007 (PMID 17227934)
• CDC Emerging Infectious Diseases — Iatrogenic Creutzfeldt-Jakob Disease from Commercial Cadaveric Human Growth Hormone (2013)
• 21 U.S.C. § 333 (Penalties; subsection (e) on human growth hormone), Cornell LII
• WADA Prohibited List — S2. Peptide Hormones, Growth Factors, Related Substances and Mimetics (Drugs.com mirror)
• IWF — New WADA Prohibited List enforced since January 1, 2026
• USADA — IGF-1 and the World Anti-Doping Agency Prohibited List