IGF-1

Muscle Approved · US & EU Human trials

Also called Mecasermin, Increlex, Insulin-like growth factor 1

The natural 70-amino-acid growth factor that carries out most of growth hormone's effects — the liver releases it in response to growth hormone, and it drives growth in muscle, bone and cartilage. The approved product is a recombinant copy.

Evidence at a glance

Evidence: Human trials — Studied in people
Status: An approved medicine in US & EU
Dosing: No human study has set a dose

Hypoglycaemia is the main acute risk, and real — it binds the insulin receptor. Sustained elevation of IGF-1 drives cell growth broadly, which is the basis of a genuine long-term cancer concern.

What studies report

Restores growth in children with severe primary IGF-1 deficiency, its approved use
Increases muscle protein synthesis
Short half-life in blood unless bound to its binding proteins

How it works

Activates the IGF-1 receptor, driving cell growth and survival. Its structural similarity to insulin also lets it bind the insulin receptor weakly, which is why it can lower blood sugar.

Binds a receptor on the cell surface and signals inward

Where it acts

Skeletal muscle

The library groups this compound under Muscle. The diagram shows that target, not every tissue it reaches.

Illustrated

Parallel bundles of human skeletal muscle fibres in close-up, one bundle gently separated to show striated fibres, anatomical specimen illustration without blood or injury.

AI-generated subject illustration; not a depiction of the compound or evidence of its effects.

Why people take it

Muscle growthGrowth failure in childrenRecovery and repair

Reasons people seek it out — not a list of proven effects.

In practice Off-label

The LR3 variant is far more common in non-medical use because plain IGF-1 is cleared within minutes
Used post-workout in bodybuilding, typically in short runs

Reported real-world use, not evidence and not a recommendation.

Status: FDA approved (Increlex, 2005) for severe primary IGF-1 deficiency. Any other use is off-label.

Route: Subcutaneous injection, from reconstituted lyophilised powder
Molecular weight: 7649 g/mol
CAS: 68562-41-4
Available as: Compounded vials

Search PubMed for IGF-1 → We link a live search rather than a fixed citation list, so it stays current and nothing here is a reference we have not checked.

Educational information only. Nothing here is medical advice, a dosing protocol, or a recommendation to use any compound. Most entries describe substances not approved for human use. Talk to a licensed clinician before acting on anything you read here. How to read these entries.