Superpower peptides available for pre-order. Get first access.

FDA-approved

Hormones & metabolism

Mecasermin

Also called rhIGF-1

EvidenceFDA approved
ClassIGF-1 (recombinant)

Mecasermin is recombinant IGF-1, FDA-approved since 2005 for children with severe primary IGF-1 deficiency. Learn how it works and who it is for.

Reviewed by
William Maish, MD MBA MPH, Clinical Product Lead
Published
October 5, 2026
Last updated
October 5, 2026

Key takeaway

Mecasermin (sold as Increlex) is recombinant human insulin-like growth factor 1 (IGF-1), used to treat children who cannot make IGF-1 or cannot respond to growth hormone. It supplies the growth signal that growth hormone would normally produce, bypassing the missing step. It has been FDA-approved in the U.S. since 2005 and is given as a twice-daily injection timed around meals.

At a glance

What it isRecombinant human insulin-like growth factor 1 (IGF-1)
Approved forGrowth failure in children with severe primary IGF-1 deficiency or growth hormone gene defects with antibodies to growth hormone
Key factIn the pivotal study, treatment raised average height velocity from about 2.8 to 8.0 cm per year in the first year
RouteSubcutaneous injection, twice daily
Evidence strengthFDA approved

What is mecasermin?

Mecasermin, sold under the brand Increlex, is a laboratory-made copy of insulin-like growth factor 1 (IGF-1), the hormone that actually carries out much of growth hormone's work in the body. Growth hormone stimulates the liver to make IGF-1, and IGF-1 then drives tissue growth. Children who cannot make IGF-1, or who cannot respond to growth hormone, do not grow normally; mecasermin provides the IGF-1 directly. It was approved in the United States in 2005.

How does mecasermin work?

Mecasermin is identical to natural IGF-1 and binds the IGF-1 receptor on cells throughout the body, directly delivering the growth-promoting signal that would normally follow growth hormone action. In children with severe primary IGF-1 deficiency, growth hormone is present but the body cannot generate IGF-1 in response, so replacing IGF-1 restores growth that growth hormone therapy alone cannot achieve.

Because IGF-1 shares actions with insulin, mecasermin can lower blood sugar, which is why it is dosed shortly before or after a meal. In the pivotal study of children with growth hormone insensitivity, IGF-1 raised average height velocity1 from about 2.8 cm per year at baseline to 8.0 cm per year in the first year of treatment.

Is it FDA-approved?

Yes. Mecasermin was approved2 by the FDA in 2005 for growth failure in children with severe primary IGF-1 deficiency, or with growth hormone gene deletion who have developed neutralizing antibodies to growth hormone. It is given as a twice-daily subcutaneous injection.

What is mecasermin prescribed for?

Mecasermin is prescribed for children with severe primary IGF-1 deficiency, a rare condition in which the body cannot produce IGF-1 despite normal or high growth hormone. It is not a treatment for ordinary growth hormone deficiency, which is treated with growth hormone itself.

What are the side effects?

According to the prescribing information2, common side effects include:

  • Low blood sugar, which is why dosing is tied to meals
  • Injection-site changes such as fatty lumps
  • Enlargement of the tonsils or adenoids

More serious considerations include:

  • Increased pressure around the brain (intracranial hypertension)
  • Slipped hip growth plate and worsening scoliosis
  • Cancers, which have been reported in children treated with mecasermin

Mecasermin is contraindicated once the growth plates have closed and in children with cancer or a history of cancer.

More for hormones & metabolism

Sources: FDA prescribing information for Increlex; a long-term study of IGF-1 therapy (Chernausek et al., Journal of Clinical Endocrinology and Metabolism, 2007, DOI: 10.1210/jc.2006-16101), indexed on PubMed. This document is educational and does not constitute medical advice.