What it is
Tesamorelin is a synthetic 44-amino acid analog of growth hormone-releasing hormone (GHRH). It is the only GHRH analog with full FDA approval, marketed as Egrifta SV. It was approved in 2010, specifically for reducing excess visceral abdominal fat in adults with HIV-associated lipodystrophy, a condition where antiretroviral therapy causes fat to redistribute into the deep abdominal (visceral) region while subcutaneous fat is lost elsewhere.
How it works
Rather than supplying growth hormone directly, tesamorelin binds GHRH receptors in the pituitary gland and stimulates the body's own pulsatile release of growth hormone, preserving natural feedback regulation in a way that injecting GH directly does not. Released GH raises IGF-1, which drives lipolysis, the breakdown of fat, particularly in visceral fat cells, which appear to be more responsive to this signalling than subcutaneous fat.
What the evidence shows
This is one of the better-evidenced compounds in this library. Two pivotal phase 3 trials, published in the New England Journal of Medicine, formed the basis of FDA approval.
In the pooled phase 3 analysis, visceral adipose tissue fell by roughly 15-18% relative to placebo, with no significant effect on subcutaneous fat, the effect is specific to the visceral depot. Benefits were maintained with continued treatment through 52 weeks. Triglycerides and total cholesterol improved alongside the fat loss. A later Harvard-led randomised trial found a 37% reduction in liver fat at 12 months, pointing to potential relevance beyond the original approved population.
Reported side effects
Because it raises GH and IGF-1, tesamorelin carries the considerations associated with that pathway: GH can cause insulin resistance, so the FDA label includes glucose monitoring as a clinical consideration. Injection site reactions are commonly reported. As with any GH-axis therapy, joint discomfort and fluid retention have also been noted.
Where it stands
Tesamorelin sits alongside tirzepatide as one of the few genuinely approved, well-evidenced compounds in this library, though for a narrower indication. Off-label use for general visceral fat or anti-aging purposes is legally possible through a prescriber but falls outside the population the trials were conducted in, and long-term data there remains incomplete.