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IGF-1 LR3 vs HGH: What the Research Shows

IGF-1 LR3 and HGH side by side: what they are, how they are regulated and what is still unknown.

Medically reviewed by Juan Pablo Frías, MD · · DisclosureUpdated
IGF-1 analogNot FDA approved · research chemicalIGF-1 LR3IGF-1 LR3, a long-acting IGF-1 analog with no published human trial; in rats it was 2.5 to 3 times more potent than IGF-I at restoring growth.[12]Growth hormone+230% searchesRecombinant growth hormoneFDA approved (prescription only)HGHRecombinant human growth hormone, FDA-approved by prescription; in a randomized trial, 4 weeks of supraphysiological dosing did not improve power output or oxygen uptake.[13]Growth hormone+39% searches
Quick verdict

Where the research points

Summary of studies, not a recommendation

Consider IGF-1 LR3 if…

No sourced contrast for this side yet. We add a point here only when it is tied to a study or label.

Consider HGH if…

  • you want products with an FDA label: Genotropin (somatropin) is indicated for children with growth failure from inadequate growth hormone secretion[7]
  • you want randomized data in adults with growth hormone deficiency: Within 3 months lean body mass rose 5.09% and body fat fell 10.89%; waist fell 1.42%.[14]

What they have in common

  • Only animal or lab studies of IGF-1 LR3 were found (e.g. rat): The IGF-I variants were 2.5-3 times more potent than IGF-I at restoring growth in diabetic rats.[12]
Both are prohibited in tested sport (WADA). Status labels come from public FDA and WADA records; see the sources below.
Side by side

Spec comparison

Showing 9 of 11 fields where the two differ. Category, PCAC vote, Jul 2026 are the same or both unknown.

FieldIGF-1 LR3HGH
ClassIGF-1 analogRecombinant growth hormone
Also calledLR3GH, growth hormone, generic HGH, IU
FDA statusNot FDA approved · research chemicalFDA approved (prescription only)
WADAProhibited by WADA (S2.3)IGF-1 and its analogues (LR3 is an IGF-1 analogue) are prohibited in S2.3, at all times.Prohibited by WADA (S2.2.3)Growth hormone and its analogues and fragments are prohibited at all times (S2.2.3).
Half-life563 min half-life in wound fluid (versus 872 min for IGF-I)wound chamber (rat) (rat) · The American journal of physiology 1999, PMID 101983020.4 hours IV; 3.0 hours subcutaneousintravenous (normal adults); subcutaneous (GHD adults), Genotropin · FDA label (Genotropin)
Evidence strengthHuman observational evidence, 3 of 4Strongest: Growth hormone & IGF research 2010, PMID 20675162Human RCT evidence, 4 of 4Strongest: Journal of applied physiology 2014, PMID 24235105
Human studies we summarised1 human (0 randomized or controlled) of 12 summarised13 human (13 randomized or controlled) of 20 summarised
Typical study doses
US searches per month22,200 · +230% searches74,000 · +39% searches

Bracketed values are pending a sourced figure. Legal data reflects the regulatory events in our tracker.

Taken together?

IGF-1 LR3 and HGH together

People also search for this pair as a stack. The stack page covers timing and interaction questions as they are sourced. Evidence for the combination: No studies tested these together (PubMed search: 0 results, 2 Oct 2026).

Open the stack page
StackIGF-1 LR3 + HGH, taken as separate injectionsStack page

Sources

  1. 1World Anti-Doping Code International Standard Prohibited List 2026World Anti-Doping Agency · 2026wada-ama.orgAccessed 2 Oct 2026
  2. 2Clearance of IGFs and insulin from wounds: effect of IGF-binding protein interactions.The American journal of physiology · 1999PMID 10198302Accessed 2 Oct 2026
  3. 3Detection of His-tagged Long-R³-IGF-I in a black market product.Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society · 2010PMID 20675162Accessed 2 Oct 2026
  4. 4IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.American journal of physiology. Endocrinology and metabolism · 2025PMID 39679943Accessed 2 Oct 2026
  5. 5Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice.Journal of Alzheimer's disease : JAD · 2025PMID 39610283Accessed 2 Oct 2026
  6. 6Insulin-like growth factor-I and analogues increase growth in artificially-reared neonatal pigs.The British journal of nutrition · 2002PMID 12067429Accessed 2 Oct 2026
  7. 7GENOTROPIN (SOMATROPIN) KIT [PFIZER LABORATORIES DIV PFIZER INC]FDA label (Genotropin), DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
  8. 8Effect of growth hormone on aging connective tissue in muscle and tendon: gene expression, morphology, and function following immobilization and rehabilitation.Journal of applied physiology (Bethesda, Md. : 1985) · 2014PMID 24235105Accessed 2 Oct 2026
  9. 9Impact of GH replacement therapy on sleep in adult patients with GH deficiency of pituitary origin.European journal of endocrinology · 2013PMID 23447518Accessed 2 Oct 2026
  10. 10Local administration of growth hormone stimulates tendon collagen synthesis in elderly men.Journal of applied physiology (Bethesda, Md. : 1985) · 2012PMID 22961272Accessed 2 Oct 2026
  11. 11PubMed search: (somatropin[tiab] OR "recombinant human growth hormone"[tiab] OR "recombinant growth hormone"[tiab] OR rhGH[tiab] OR "growth hormone therapy"[tiab] OR "growth hormone treatment"[tiab] OR "growth hormone replacement"[tiab] OR "growth hormone administration"[tiab] OR "GH therapy"[tiab] OR "GH treatment"[tiab] OR "GH replacement"[tiab] OR "GH administration"[tiab] OR "growth hormone injection"[tiab] OR "growth hormone injections"[tiab] OR "growth hormone supplementation"[tiab]) AND ("Long R3"[tiab] OR (LR3[tiab] AND (IGF[tiab] OR "IGF-1"[tiab] OR "IGF-I"[tiab] OR "insulin-like growth factor"[tiab])))PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  12. 12Insulin-like growth factor-I and more potent variants restore growth of diabetic rats without inducing all characteristic insulin effects.The Biochemical journal · 1993PMID 7683875Accessed 2 Oct 2026
  13. 13Short-term administration of supraphysiological recombinant human growth hormone (GH) does not increase maximum endurance exercise capacity in healthy, active young men and women with normal GH-insulin-like growth factor I axes.The Journal of clinical endocrinology and metabolism · 2005PMID 15784718Accessed 2 Oct 2026
  14. 14Two years of replacement therapy in adults with growth hormone deficiency.Clinical endocrinology · 1997PMID 9404448Accessed 2 Oct 2026

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