What Is Tesamorelin and How Does It Work
Tesamorelin is a synthetic, stabilized analogue of growth hormone-releasing hormone (GHRH), the hypothalamic signal that triggers the pituitary gland to secrete growth hormone. Compared with native GHRH, tesamorelin carries a chemical modification that increases its resistance to enzymatic breakdown, extending its usable activity enough to support once-daily dosing. It acts through the same GHRH receptor pathway as the body's own hormone, producing a more physiologic, pulsatile rise in growth hormone and downstream IGF-1 rather than the flat, supraphysiologic elevation seen with direct growth hormone injections.
Unlike most peptides covered on this site, tesamorelin is a legitimate, FDA-approved prescription drug, marketed under the brand names Egrifta, Egrifta SV, and Egrifta WR by Theratechnologies. That approval, however, is narrow - see Regulatory Status below.
Important distinction: Tesamorelin's FDA approval covers exactly one indication - reduction of excess visceral abdominal fat in HIV-infected adults with lipodystrophy. It is not approved for general population fat loss, bodybuilding, anti-aging, or cognitive enhancement use. Any use outside that specific HIV-lipodystrophy indication - including with the branded prescription product - is off-label and has not been evaluated by the FDA for safety or effectiveness in that context.
Research Dosing
Dosing below reflects the FDA-approved regimen used in the pivotal clinical trials, which is distinct from research-community dosing used for off-label purposes - those off-label protocols have not been validated in the controlled trials that support the approved indication.
| Formulation | Dose | Frequency | Route |
|---|---|---|---|
| Egrifta (original) | 2mg | Once daily | SubQ injection |
| Egrifta SV | 1.4mg (reconstituted) | Once daily | SubQ injection |
| Egrifta WR | 1.28mg (from weekly-mixed vial) | Once daily | SubQ injection |
All three formulations are dosed every day; the "WR" name refers to the vial being reconstituted once per week and then drawn into individual daily doses, not to a once-weekly injection schedule. Off-label research use for general fat loss or cognitive-effect purposes commonly cites daily subcutaneous dose ranges similar to the approved regimen, but these off-label protocols have not been validated in the trials supporting FDA approval.
Regulatory Status
Tesamorelin holds FDA approval - the only GHRH analogue with that status - specifically for reduction of excess visceral abdominal fat in HIV-infected patients with lipodystrophy, based on the pivotal Falutz et al. trial described below. That approval does not extend to other populations or goals: using tesamorelin, whether the branded prescription product or a research-chemical version, for general fat loss, athletic performance, or cognitive enhancement is off-label and unapproved use, even when the drug itself is legitimately manufactured. Tesamorelin sold as a research chemical outside a prescription is a separate, non-FDA-evaluated product marketed for laboratory use only, not for human consumption. Consult a qualified healthcare provider, ideally one familiar with HIV-associated lipodystrophy, before considering treatment.
What Research Shows
The evidence supporting tesamorelin's approved indication is substantial: a 26-week, multicenter, double-blind, placebo-controlled Phase 3 trial in HIV-infected patients found a significant, selective reduction in visceral fat with tesamorelin versus placebo, alongside improvements in triglycerides and total cholesterol, without significant adverse effects on glycemic measures.
Separately, and outside the approved indication, a randomized, placebo-controlled trial in older adults - including some with mild cognitive impairment - examined tesamorelin's effect on cognitive function. That study reported improved executive function across both groups and improved delayed verbal recall specifically in the mild-cognitive-impairment group after 20 weeks of daily dosing.
This cognitive-function research is a separate, off-label line of investigation from the visceral-fat evidence underlying FDA approval, and the evidence base there is smaller and less established than the data supporting the approved indication.