Somatropin (HGH)
Growth hormone itself: the 191-amino-acid hormone the pituitary makes, rather than a peptide that tells the pituitary to release it.
FDA-approved (Genotropin, Norditropin, Omnitrope and others) for GH deficiency; not approved for anti-aging.
Used for
- Adult GH deficiency (diagnosed by testing)
- Body composition: less fat, more lean mass
- Recovery and skin (off-label)
How it works
Acts on GH receptors, mainly in the liver, which makes IGF-1; GH and IGF-1 together burn fat, build lean tissue and raise blood sugar. Unlike GH peptides it bypasses the pituitary, so the body’s own pulses and feedback are switched off while on it.
Half-life: a few hours after a shot under the skin (IGF-1 stays up longer)
What the research shows
- A systematic review of GH in healthy older adults: about 2 kg less fat and 2 kg more lean mass, but no gain in strength or fitness, and more swelling, joint pain, carpal tunnel and breast growth in men.
- A 26-week trial in healthy older men and women found the same body-composition changes; 18 men developed glucose intolerance or diabetes.
- In diagnosed adult GH deficiency, treatment improves body composition, bone density and quality of life (Endocrine Society guideline).
Dosing
Dosing isn’t listed on the public site. In the app, each published option is shown with its source (a drug label, a clinical guideline, a trial or community reports) and can be turned into a protocol you review.
Work out the units to draw for your vial →Side effects
- Water retention and swelling
- Joint aches, carpal tunnel (numb or tingling hands)
- Higher blood sugar and insulin
- Breast growth in men
Cautions
- Raises GH and IGF-1. Avoid with active cancer or a history of it; can raise blood sugar. Check IGF-1 and fasting glucose on bloodwork.
- Dose by IGF-1 on bloodwork: aim for mid-normal for your age, not above it.
- “191aa” from gray-market sellers is often underdosed or impure; pharmacy GH is dosed in mg on the pen.
- Prohibited in tested sports (WADA).
Storage
Unmixed or unopened: Fridge (2–8 °C) in the carton, away from light. Never freeze (or the diluent).
Mixed or in use: Fridge. The labels allow 14 to 28 days depending on the brand and vial size (Zomacton: 14 days for the 5 mg vial, 28 days for the 10 mg; Genotropin pen: 28 days), so follow your brand’s label.
From the Zomacton, Genotropin and Humatrope labels.
Stability once mixed
A large protein: the labels give 14 to 28 days once mixed, and shaking or freezing damages it. Swirl gently, never shake.
Heat, shaking, freezing a mixed vial, light and many needle punctures all speed breakdown. Toss it if it turns cloudy, grows specks or changes color.
One storage test
Fridge (2–8 °C), drawn into polypropylene syringes: no loss of purity or potency at 7, 14, 21 or 28 days (1 and 3.33 mg/mL), same as the glass vial.
Fridge, propylene-ethylene copolymer syringes: too cloudy after 21 days; fine to 14 days.
Lilly’s own somatropin (Humatrope) mixed with its diluent (m-cresol preservative), measured by HPLC. Peer reviewed. Research hGH mixed in bacteriostatic water was not tested, and the syringe’s plastic mattered. A single test, not a use-by date. Ray & Chen 1998, Am J Health Syst Pharm, Eli Lilly (PMID 9676297)
Interactions
Glucocorticoid replacement (cortisone, prednisone) may need a higher dose after starting, and a hidden adrenal shortfall can show up.
Oral estrogen: women may need larger somatropin doses.
Insulin and other blood-sugar drugs may need adjusting.
It may change how the liver clears drugs processed by CYP450 enzymes (corticosteroids, sex steroids, anticonvulsants, cyclosporine): monitor.
Not a full list. Tell your doctor and pharmacist everything you take.
More in Growth hormone
Reference only, not medical advice. Written for this app from the cited research. Doses marked community-reported are not from trials.