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Prescription medication — not a dietary supplement
Mecasermin (IGF-1)is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Most Mecasermin (IGF-1) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality studies published 1999–2023 with a typical study size of 76 participants.
Based on 6 studies · 349 total participants
Confidence
LowBy outcome
Mecasermin (IGF-1) has an evidence score of 3.5/10 — emerging evidence based on 6 indexed studies. The pharmaceutical-grade version of IGF-1 — an FDA/EMA-approved prescription injectable, but approved ONLY for a rare childhood growth disorder (severe primary IGF-1 deficiency / Laron syndrome), where it genuinely raises height velocity in clinical trials. It is the regulated counterpart to the grey-market igf-1-lr3 peptide bodybuilders inject, and shares the same core risks. Crucially, there is NO trial supporting its off-label use for muscle, performance, or anti-aging in healthy adults — and IGF-1's documented harms (hypoglycemia, intracranial hypertension, lymphoid/tonsillar hypertrophy, and a theoretical cancer concern because IGF-1 is mitogenic) are real. Not a dietary supplement, not a longevity drug. Representative study: PMID 17192294.
The commonly studied dose of Mecasermin (IGF-1) is A prescription drug for a rare growth disorder, not a performance supplement — this library does NOT provide an off-label dosing protocol. In the approved indication, mecasermin is dosed by a pediatric endocrinologist, started low (e.g. ~40 µg/kg) and titrated up to ~120 µg/kg subcutaneously twice daily, ALWAYS given shortly before or after a meal/snack to prevent hypoglycemia. There is no validated dose for muscle, performance, or anti-aging use because no such trial exists.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Insulin (bodybuilding use)
Mostly mechanism / observationalInsulin is a life-saving prescription hormone for diabetes — and, used illicitly by bodybuilders as an off-label 'anabolic,' one of the most dangerous performance drugs in existence. The theory is nutrient partitioning: insulin drives glucose and amino acids into muscle and suppresses muscle-protein breakdown. But there is NO controlled evidence that insulin builds muscle or improves performance in healthy, non-diabetic athletes — and a non-diabetic who injects it risks profound, sometimes FATAL hypoglycemia (coma, seizures, brain injury, death), plus fat gain. This is a harm-reduction reference documenting a popular, deadly misuse, NOT a recommendation and NOT a dietary supplement.
Last reviewed June 2026 · evidence from 6 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Mecasermin (recombinant human IGF-1, Increlex)
The pharmaceutical-grade version of IGF-1 — an FDA/EMA-approved prescription injectable, but approved ONLY for a rare childhood growth disorder (severe primary IGF-1 deficiency / Laron syndrome), where it genuinely raises height velocity in clinical trials. It is the regulated counterpart to the grey-market igf-1-lr3 peptide bodybuilders inject, and shares the same core risks. Crucially, there is NO trial supporting its off-label use for muscle, performance, or anti-aging in healthy adults — and IGF-1's documented harms (hypoglycemia, intracranial hypertension, lymphoid/tonsillar hypertrophy, and a theoretical cancer concern because IGF-1 is mitogenic) are real. Not a dietary supplement, not a longevity drug.
Mecasermin is an approved, well-studied prescription drug — but only for the rare disorder of severe primary IGF-1 deficiency, where multi-year trials confirm increased height velocity. For the off-label muscle/performance/anti-aging use that brings most people to it, there is no supporting trial, it shares igf-1-lr3's risks (hypoglycemia, mitogenic/cancer concern), and it carries documented harms (intracranial hypertension, lymphoid hypertrophy). Low-moderate, Emerging.
Mecasermin is recombinant human insulin-like growth factor-1 (rhIGF-1) — the same molecule the body makes downstream of growth hormone — manufactured as a prescription drug (brand Increlex) and given as a twice-daily subcutaneous injection.
It is approved for one narrow indication: severe primary IGF-1 deficiency (SPIGFD), including Laron syndrome, a rare disorder in which children cannot make IGF-1 in response to growth hormone and so remain extremely short. In that population the evidence is genuinely solid.
The pivotal long-term trial (Chernausek et al., 2007) treated 76 such children for up to 12 years and roughly tripled first-year height velocity (2.8 → 8.0 cm/yr); the long-term follow-up to adult height (Backeljauw et al., 2013) showed a mean gain of ~13 cm over the untreated expectation, and real-world registry data (Bang et al., 2021; Ramon-Krauel et al., 2026) confirm linear-growth benefit across hundreds of patients.
This is a legitimate, evidence-based therapy for a rare growth disorder.
The honest framing this entry exists to deliver: mecasermin is the pharma counterpart to the grey-market igf-1-lr3 peptide, and it is increasingly sourced off-label by bodybuilders and anti-aging users on the theory that 'more IGF-1 = more muscle / younger tissue.' There is NO clinical trial of mecasermin (or any rhIGF-1) for muscle growth, strength, fat loss, performance, or longevity in healthy adults.
The anabolic rationale is real biology — IGF-1 binds the IGF-1 receptor and drives PI3K/Akt/mTOR protein synthesis, and short rhIGF-1/IGFBP-3 infusions did improve leg muscle protein balance in severely burned, catabolic patients (Debroy et al., 1999) — but a benefit in catabolic illness is not a benefit in a healthy lifter, and that study is the closest 'muscle' evidence that exists.
Against that absent benefit sit documented harms from the approved trials themselves: hypoglycemia is the single most common adverse event (reported by ~49% of treated children — IGF-1 has insulin-like activity), tonsillar/adenoidal (lymphoid) hypertrophy occurred in ~22%, and intracranial hypertension is a recognized class effect.
On top of that, IGF-1 is mitogenic and IGF-1 receptors are overexpressed on many tumors, so chronically amplifying the IGF-1 axis carries a theoretical cancer-promotion concern, and animal work shows organ hypertrophy (kidney, spleen, heart).
An independent drug bulletin (Prescrire, 2009) judged that even in the approved indication the modest height benefit did 'not justify exposure to its potential risks' for many patients.
So: a real, approved, well-studied drug for a rare growth disorder — scored in the low-moderate range because for the performance/anti-aging use that brings most people here, it has zero supporting evidence, carries the same risks as the grey-market analog, and is a prescription drug rather than a supplement.
Sandboxed out of all goal- and stack-based recommendations.
Mecasermin is native human IGF-1; it binds the IGF-1 receptor and activates the PI3K/Akt/mTOR and ERK/MAPK cascades that drive protein synthesis, cell proliferation, and longitudinal bone growth. This is the mechanism behind the approved growth benefit and the (untested-in-healthy-people) anabolic rationale.
In severe primary IGF-1 deficiency, growth hormone is present but cannot generate IGF-1 (or the receptor is defective), so GH treatment fails. Replacing IGF-1 directly restores the growth signal at the growth plate — roughly tripling first-year height velocity in the pivotal trial (Chernausek et al., 2007).
IGF-1 shares structural homology with insulin and cross-activates insulin signaling, lowering blood glucose. This is why hypoglycemia is the most common adverse event in treated patients (~49%) and a core safety concern for any IGF-1 use.
How Mecasermin (IGF-1) works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Tap node to isolate • Pinch to zoom • Tap edge for research
A prescription drug for a rare growth disorder, not a performance supplement — this library does NOT provide an off-label dosing protocol. In the approved indication, mecasermin is dosed by a pediatric endocrinologist, started low (e.g. ~40 µg/kg) and titrated up to ~120 µg/kg subcutaneously twice daily, ALWAYS given shortly before or after a meal/snack to prevent hypoglycemia. There is no validated dose for muscle, performance, or anti-aging use because no such trial exists.
Take with food
| Form | Type |
|---|---|
| 💊Prescription rhIGF-1 injection (Increlex) — approved-indication use only | Recommended |
| 💊Mecasermin rinfabate (rhIGF-1/IGFBP-3 complex, iPLEX) — a once-daily complexed form with a similar effect and side-effect profile | Alternative |
There is no over-the-counter or supplement form. Mecasermin is a prescription biologic; igf-1-lr3 is the unregulated grey-market analog people self-inject instead.
Minimum: 52 weeks
Optimal: 260 weeks
Cycling: Not required
Note: In the approved indication, taken twice daily with a meal/snack to prevent hypoglycemia. This library does not endorse or schedule off-label use.
Dose-response data unavailable. The current published research for Mecasermin (IGF-1) does not provide sufficient dose-specific outcome data to generate reliable dose-response curves.
Refer to the Dosage & Timing section above for recommended dose ranges based on available evidence.
In children with severe primary IGF-1 deficiency, rhIGF-1 raised mean first-year height velocity from ~2.8 to ~8.0 cm/yr (Chernausek et al., 2007) and produced a ~13 cm gain over the untreated expectation by adult height (Backeljauw et al., 2013). A genuine, trial-proven benefit — but only in this rare disorder.
Despite being injected off-label for muscle and 'anti-aging,' there is no clinical trial of mecasermin for muscle growth, strength, fat loss, recovery, or longevity in healthy adults. Every such claim is extrapolated from the growth-disorder data or from IGF-1 biology — not demonstrated.
A 5-day rhIGF-1/IGFBP-3 infusion improved leg muscle protein balance and fractional synthetic rate in severely burned adults without causing glucose abnormalities (Debroy et al., 1999). A real anabolic signal — but in a catabolic clinical state, not healthy lifters, and over days.
IGF-1's insulin-like activity lowers blood glucose; hypoglycemia was the single most common adverse event in the pivotal trial (~49% of treated children) and the most common AE in registry data. Mecasermin must be taken with a meal/snack for this reason.
Tonsillar/adenoidal (lymphoid) hypertrophy occurred in ~22% of treated children — sometimes causing snoring, otitis, or hearing changes — and benign intracranial hypertension (headache, vision changes) is a recognized class effect. Both are documented in the approved-indication trials.
IGF-1 is mitogenic and its receptor is overexpressed on many tumors; chronically amplifying the IGF-1 axis carries a theoretical risk of promoting existing or nascent cancers. Animal studies also show organ hypertrophy. Never quantified in off-label healthy users.
Avoid — there is no trial supporting benefit, it is a prescription drug, and it carries documented hypoglycemia, lymphoid-hypertrophy, intracranial-hypertension, and theoretical cancer risks.
Avoid — IGF-1-axis activation is a recognized theoretical tumor-promotion risk.
Avoid or use only with intensive glucose monitoring — IGF-1 lowers blood glucose and can compound glucose-lowering medications.
Avoid — a potent growth-factor agonist not adequately studied in human pregnancy.
IGF-1 has insulin-like activity and lowers blood glucose; combining it with insulin, sulfonylureas, or other hypoglycemic agents can compound blood-sugar lowering and precipitate dangerous hypoglycemia.
Stacking with growth hormone or other anabolics further amplifies IGF-1-axis signaling and the associated organ-overgrowth and cancer-promotion concerns. Not studied for off-label combined use.
Tip: The most common adverse event (~49% in the pivotal trial). Always take with a meal/snack; symptomatic or severe hypoglycemia can occur, especially when fasting or combined with glucose-lowering drugs.
Tip: Occurred in ~22% of treated children; can cause snoring, sleep apnea, otitis, or hearing changes and sometimes requires ENT evaluation or surgery.
Tip: A recognized class effect of IGF-1; report persistent headache, nausea, or vision changes promptly. May require fundoscopic monitoring and dose interruption.
Tip: Reported by ~32% in the pivotal trial; rotate injection sites.
The best time to take Mecasermin (IGF-1) is with meals. Take it with food. In the approved indication, each dose is given within ~20 minutes of a meal or snack to offset IGF-1's blood-glucose-lowering (insulin-like) effect.
Mecasermin (IGF-1) should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are hypoglycemia (low blood sugar), tonsillar / adenoidal (lymphoid) hypertrophy, benign intracranial hypertension (headache, vision changes). Use caution if any of these apply to you: Active or suspected cancer, or a history of malignancy — IGF-1 is mitogenic and a theoretical tumor-promotion risk; Closed epiphyses / completed growth when used for the growth indication; Intracranial hypertension or unexplained severe headaches.
Semaglutide
Mostly mechanism / observationalAn FDA-approved GLP-1 receptor agonist (Ozempic/Rybelsus for type 2 diabetes, Wegovy for chronic weight management) with genuinely strong, large-RCT evidence for glycemic control and substantial weight loss, plus a cardiovascular-outcomes benefit. Honest appraisal: this is a real prescription medicine with real efficacy AND real risks — a boxed warning for thyroid C-cell tumors, pancreatitis and gallbladder risk, very common GI side effects, and growing concern about grey-market/compounded versions. It is included here for reference only, not as a supplement and not auto-recommended.
IGF-1 promotes cell proliferation and survival, and IGF-1 receptors are overexpressed on many tumor types. Chronically raising IGF-1 signaling is a recognized theoretical cancer-promotion concern; animal work shows visceral-organ hypertrophy (kidney, spleen, heart).
Glucocorticoids can blunt the growth-promoting and anabolic effects of IGF-1; dose adjustments are managed by the prescribing specialist in the approved indication.
Tip: IGF-1 is mitogenic and its receptor is overexpressed on many cancers; avoid with any active or prior malignancy. Long-term risk in off-label users is unquantified.
Tip: Animal studies show visceral-organ hypertrophy with sustained IGF-1 agonism; relevance to human off-label dosing is unknown.