Where to Buy HGH: Vendor Comparison, Benefits & Side Effects

HGH is recombinant human growth hormone — somatropin — a 191-amino-acid protein identical in sequence to the main form the human pituitary secretes. It is a folded protein, not a short synthetic peptide, so identity and purity matter more. It is sold strictly as a research chemical: not the approved prescription medicine, and nothing on this page is medical advice.

Somatropin is also a licensed drug, approved since the 1980s for growth hormone deficiency and a few other diagnosed conditions, so unusually its pharmacology is characterised largely in humans. That evidence belongs to pharmaceutical product and those indications; outside them, a systematic review of trials in healthy older adults found small body-composition changes, more adverse effects and no clear functional benefit.

PeptidesFinder's role is narrower than the science. We track which research vendors list HGH, normalise listings to a price per milligram so vial sizes can be compared, and record whether a recent certificate of analysis is on file. Because somatropin is often labelled in international units rather than by weight, an IU-only listing is not compared per milligram until the vendor states its mg content. The comparison is re-checked on an automated schedule; confirm current pricing on the vendor's own site before ordering.

Somatropin's pharmacology is better characterised than almost anything else on this site, because the approved drug has been studied in humans for decades. That is true of the pharmaceutical product; the research-grade material sold by these vendors has not been through the same testing, and what follows describes the hormone, not any vial.

Receptor target. Growth hormone binds the growth hormone receptor (GHR), a class I cytokine receptor on liver, fat, muscle, bone and cartilage. Structural work on the human receptor shows one hormone molecule engaging a pre-formed receptor pair and rotating the subunits so their associated JAK2 kinases phosphorylate the receptor and the transcription factor STAT5b. In humans, inactivating mutations in GHR (Laron syndrome) or STAT5b abolish the growth response — the clearest evidence that this pathway carries the signal in people.

IGF-1 axis. Much of the growth effect runs through insulin-like growth factor 1, produced by the liver under GHR signalling — the somatomedin hypothesis of Salmon and Daughaday (1957). Animal models complicate it: mice lacking hepatic IGF-1 lose most of their circulating IGF-1 yet grow almost normally, and growth hormone injected into one tibial growth plate of a hypophysectomised rat accelerates growth on that side only, so the hormone also acts directly on tissue and through locally made IGF-1. Serum IGF-1 is the marker used to monitor the approved drug.

Metabolic actions. Growth hormone is also a metabolic hormone; these effects come from human infusion and clamp studies and from the approved labelling. It stimulates lipolysis and antagonises insulin — peripheral glucose uptake falls and hepatic glucose output rises, which is why impaired fasting glucose and, in some patients, diabetes are recognised adverse effects. It increases protein synthesis and nitrogen retention and makes the kidney retain sodium and water; fluid retention, joint pain and carpal tunnel syndrome are the most frequently reported adverse effects in adult trials.

Regulation and feedback. Endogenous growth hormone is released from the pituitary in pulses, largely during slow-wave sleep: hypothalamic GHRH stimulates release, somatostatin inhibits it, ghrelin amplifies it through a separate receptor, and IGF-1 feeds back to suppress it. Administered growth hormone suppresses the body's own pulsatile output while present. The GH secretagogues also listed in this category act upstream on the pituitary, not at the GHR.

Human evidence, and its limits. Controlled trials cover the approved indications — growth hormone deficiency in children and adults and a few other diagnosed conditions such as Turner syndrome and growth failure in chronic kidney disease. Outside those, a 2007 systematic review of trials in healthy older adults found small changes in body composition, no clear functional benefit and more adverse effects. Growth hormone is prohibited in sport by the World Anti-Doping Agency. There are no controlled human studies of research-grade somatropin from non-pharmaceutical sources; its identity, potency and impurity profile rest on the vendor's certificate of analysis.

Somatropin is a prescription medicine, approved for specific diagnosed conditions and prescribed and monitored by physicians. The research-grade material sold by the vendors listed here is not that approved product: it has not been manufactured, tested or dispensed under the same controls, and none of the findings above establishes its safety or efficacy in humans. It is not approved for any use.