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IGF-1 vs HGH: What the Research Shows

IGF-1 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
[class][status]IGF-1Growth factor whose recombinant form (mecasermin) was tested in Rett syndrome; a randomised phase II trial did not show significant improvement in primary outcomes.[7]
Recombinant 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.[8]Growth hormone+39% searches
Quick verdict

Where the research points

Summary of studies, not a recommendation

Consider IGF-1 if…

  • you want an FDA-approved product: Increlex (mecasermin) is indicated for growth failure in children with severe primary IGF-1 deficiency[9]

Consider HGH if…

  • you want products with an FDA label: Genotropin (somatropin) is indicated for children with growth failure from inadequate growth hormone secretion[2]
  • 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%.[10]

What they have in common

  • IGF-1 (mecasermin) and its analogues is prohibited by WADA at all times, in and out of competition[1]
  • Growth hormone is prohibited by WADA at all times, in and out of competition[1]
IGF-1 is not FDA approved. HGH is prohibited in tested sport (WADA). Status labels come from public FDA and WADA records; see the sources below.
Side by side

Spec comparison

Showing 8 of 9 fields where the two differ. PCAC vote, Jul 2026 are the same or both unknown.

FieldIGF-1HGH
Class[class]Recombinant growth hormone
Also called—GH, growth hormone, generic HGH, IU
FDA status[status]FDA approved (prescription only)
WADANo WADA record in our dataProhibited by WADA (S2.2.3)Growth hormone and its analogues and fragments are prohibited at all times (S2.2.3).
Half-life[half-life by route]0.4 hours IV; 3.0 hours subcutaneousintravenous (normal adults); subcutaneous (GHD adults), Genotropin · FDA label (Genotropin)
Evidence strength[evidence grade]Human RCT evidence, 4 of 4Strongest: Journal of applied physiology 2014, PMID 24235105
Human studies we summarised[n]13 human (13 randomized or controlled) of 20 summarised
Typical study doses[dose range]

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

Taken together?

IGF-1 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: 3434 results, 2 Oct 2026).

Open the stack page
StackIGF-1 + 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. 2GENOTROPIN (SOMATROPIN) KIT [PFIZER LABORATORIES DIV PFIZER INC]FDA label (Genotropin), DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
  3. 3Effect 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
  4. 4Impact of GH replacement therapy on sleep in adult patients with GH deficiency of pituitary origin.European journal of endocrinology · 2013PMID 23447518Accessed 2 Oct 2026
  5. 5Local administration of growth hormone stimulates tendon collagen synthesis in elderly men.Journal of applied physiology (Bethesda, Md. : 1985) · 2012PMID 22961272Accessed 2 Oct 2026
  6. 6PubMed 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 ("IGF-1"[tiab] OR "IGF-I"[tiab] OR "insulin-like growth factor 1"[tiab] OR "insulin-like growth factor I"[tiab] OR mecasermin[tiab])PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  7. 7Molecular Signatures of Response to Mecasermin in Children With Rett Syndrome.Frontiers in neuroscience · 2022PMID 35712450Accessed 2 Oct 2026
  8. 8Short-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
  9. 9INCRELEX prescribing information (FDA label)FDA label, DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
  10. 10Two years of replacement therapy in adults with growth hormone deficiency.Clinical endocrinology · 1997PMID 9404448Accessed 2 Oct 2026

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