HGH (Somatropin) vs IGF-1 LR3 (Long R3 IGF-1)
Updated September 21, 2026 · Reviewed by the PeptidesDB Editorial team
A data-driven comparison of HGH (Somatropin) and IGF-1 LR3 (Long R3 IGF-1) (also searched as IGF-1 LR3 (Long R3 IGF-1) vs HGH (Somatropin)) — effect profiles, evidence, side effects, and which suits weight loss, muscle, or healing goals.
Verdict
HGH (Somatropin) centers on muscle, while IGF-1 LR3 (Long R3 IGF-1) leans toward muscle. On indexed research, HGH (Somatropin) is ahead (HGH (Somatropin): 55 studies, Human clinical; IGF-1 LR3 (Long R3 IGF-1): 14, Human evidence). Choose by goal — and read the primary studies. This is research information, not medical advice.
Key takeaways
- •HGH (Somatropin) is strongest for muscle; IGF-1 LR3 (Long R3 IGF-1) for muscle.
- •Evidence: HGH (Somatropin) Human clinical (55 studies) vs IGF-1 LR3 (Long R3 IGF-1) Human evidence (14).
- •Check the FDA-approval status chips above before assuming a legal use pathway.
Effect profiles, overlaid
At a glance
Growth stimulation | Growth hormone deficiency
IGF-1 receptor agonist | Muscle growth
HGH (Somatropin) vs IGF-1 LR3 (Long R3 IGF-1): side-by-side
| Metric | HGH (Somatropin) | IGF-1 LR3 (Long R3 IGF-1) |
|---|---|---|
| Class | Healing | Muscle |
| Regulatory status | FDA-approved | Research use only |
| Evidence grade | Human clinical | Human evidence |
| Studies indexed | 55 | 14 |
| Research level | FDA Approved | Preclinical |
| Strongest effect | Muscle & body comp | Muscle & body comp |
| Healing & recovery | 4.0▲ | 1.0 |
| Muscle & body comp | 5.0▲ | 5.0▲ |
| Metabolic & appetite | 4.0▲ | 3.0 |
| Neuro & mood | 2.0▲ | 2.0▲ |
| Sleep & circadian | 2.0▲ | 0.0 |
| Inflammation & immune | 3.0▲ | 1.0 |
| Skin & aesthetics | 4.0▲ | 2.0 |
▲ marks the higher AI-assigned effect score (0–5, describing where the literature concentrates — not clinical efficacy).
Mechanism & pharmacokinetics
| Property | HGH (Somatropin) | IGF-1 LR3 (Long R3 IGF-1) |
|---|---|---|
| Mechanism | IGF-1 activation | IGF-1 receptor agonist |
| Route | Subcutaneous injection | Subcutaneous injection |
| Half-life | ~20 min | ~20-30 hours |
| Time to peak | 3–6 hours | — |
| Duration of action | variable | — |
Established pharmacology — curated for well-characterized compounds and AI-summarized otherwise. A blank (—) means no reliable single value is published (half-life figures for some peptides genuinely disagree across sources). Verify against primary sources such as FDA labels and ClinicalTrials.gov.
What is HGH (Somatropin)?
HGH (somatropin) is recombinant human growth hormone, FDA-approved for pediatric and adult GH deficiency and several wasting and short-stature conditions; widely studied for body composition off-label.
Full HGH (Somatropin) profile, mechanism & studies →What is IGF-1 LR3 (Long R3 IGF-1)?
IGF-1 LR3 is a long-acting synthetic IGF-1 analog with reduced binding-protein affinity, used as a research-grade IGF-1 receptor agonist studied for muscle and tissue growth.
Full IGF-1 LR3 (Long R3 IGF-1) profile, mechanism & studies →Which is better for your goal?
| Goal | Better fit | Why |
|---|---|---|
| Healing | HGH (Somatropin) | 4.0/5 effect signal |
| Muscle | Even | Both ~5.0/5 |
| Metabolic | HGH (Somatropin) | 4.0/5 effect signal |
| Neuro | Even | Both ~2.0/5 |
| Sleep | HGH (Somatropin) | 2.0/5 effect signal |
| Inflammation | HGH (Somatropin) | 3.0/5 effect signal |
| Skin | HGH (Somatropin) | 4.0/5 effect signal |
Fit reflects community-perceived effect profiles — not head-to-head trials. Read each peptide's studies before deciding.
Can you stack HGH (Somatropin) and IGF-1 LR3 (Long R3 IGF-1)?
People sometimes combine peptides that target different pathways, but there is little controlled research on this specific pairing and the interactions aren't well characterized. Because at least one is a research-use compound, we don't publish stacking or dosing protocols here. Any combination should be discussed with a qualified clinician.
HGH (Somatropin) vs IGF-1 LR3 (Long R3 IGF-1): side effects
No community-reported effects logged yet.
No community-reported effects logged yet.
Anonymous community reports (count = number of reports), not clinical incidence rates.
What the research says
HGH (Somatropin) has 55 approved studies indexed (Human clinical), and IGF-1 LR3 (Long R3 IGF-1) has 14 (Human evidence). The Librarian re-checks PubMed, Europe PMC and ClinicalTrials daily, so these counts move. Open each profile to read the summaries and sources.
Frequently asked questions
Is HGH (Somatropin) or IGF-1 LR3 (Long R3 IGF-1) better?
It depends on your goal. HGH (Somatropin) is strongest for muscle; IGF-1 LR3 (Long R3 IGF-1) for muscle. HGH (Somatropin) has more indexed studies (55). See the goal-by-goal breakdown above.
Is HGH (Somatropin) or IGF-1 LR3 (Long R3 IGF-1) better for weight loss?
HGH (Somatropin) shows the stronger metabolic & appetite profile (4.0/5) in the AI-assigned effect profile — though weight-loss outcomes depend on the individual and the evidence base.
Is HGH (Somatropin) or IGF-1 LR3 (Long R3 IGF-1) better for muscle?
Both land close on the muscle & body-composition axis.
Which has more research, HGH (Somatropin) or IGF-1 LR3 (Long R3 IGF-1)?
HGH (Somatropin) has 55 approved studies indexed (Human clinical); IGF-1 LR3 (Long R3 IGF-1) has 14 (Human evidence). Higher counts mean more to read, not proven superiority.
Can you stack HGH (Somatropin) and IGF-1 LR3 (Long R3 IGF-1)?
Some users combine peptides, but there's little controlled data on this specific pairing, and interactions aren't well characterized. We don't publish stacking protocols for compounds that aren't FDA-approved. Discuss any combination with a qualified clinician.
What are the side effects of HGH (Somatropin) vs IGF-1 LR3 (Long R3 IGF-1)?
HGH (Somatropin): no community-reported effects logged yet. IGF-1 LR3 (Long R3 IGF-1): none logged yet. These are anonymous reports, not incidence rates — see each profile.
Is HGH (Somatropin) or IGF-1 LR3 (Long R3 IGF-1) FDA-approved?
HGH (Somatropin) is FDA-approved. IGF-1 LR3 (Long R3 IGF-1) is not FDA-approved. Research-use status is not a legal clearance to compound or use in humans.
Is IGF-1 LR3 (Long R3 IGF-1) better than HGH (Somatropin)?
For muscle, IGF-1 LR3 (Long R3 IGF-1) has the edge; for muscle, HGH (Somatropin) does. Neither is universally "better" — it's goal-dependent, and both should be weighed against their evidence base above.
Comparing related peptides
Regulatory & legal status
Approval status varies (see the chips at the top). FDA approval and compounding rules for peptides change frequently, and research-use status is not a legal clearance for human use. The FDA does not review compounded drugs for safety, effectiveness, or quality. Verify current status with primary sources before acting. Last reviewed September 21, 2026.