Tesamorelin is the compound people reach for when the problem is not overall weight but the deep, hard belly fat that will not move. It is also one of the few peptides in this space with a genuine FDA approval and real human trial data behind its main use. That also means there is a precise approved dose on the label, which differs from the protocol the research-peptide world typically runs, and getting that distinction right matters. Here is the full breakdown.
What is tesamorelin?
Tesamorelin is a synthetic 44-amino-acid peptide that mimics the body's growth hormone-releasing hormone (GHRH). It is not growth hormone itself; instead it signals the pituitary to release more of the body's own growth hormone in natural pulses, which in turn raises IGF-1. It is FDA-approved under the brand name EGRIFTA SV for the reduction of excess abdominal fat in HIV-infected adults with lipodystrophy, and it is studied beyond that for metabolic issues, liver fat, and aging. The approval is what separates it from pure research-chemical territory: there is real, controlled trial data behind the primary indication.
How it works
The chain is straightforward. Tesamorelin binds GHRH receptors in the pituitary, the pituitary pulses out growth hormone, and that growth hormone raises IGF-1. Downstream, this drives lipolysis (the breakdown of fat) with a notable preference for visceral fat specifically, the deep fat packed around the organs that produces a hard, distended midsection, as opposed to the soft subcutaneous fat that can be pinched. In the registration trials, daily use meaningfully reduced visceral fat and improved lipid measures over six to twelve months. The same GH and IGF-1 increase is why it is being explored for liver fat and age-related decline, since natural GH output falls as people get older.
The evidence
Tesamorelin is better-supported than most compounds discussed in this space. Its visceral-fat reduction is FDA-approved and backed by two large randomized, double-blind, placebo-controlled trials in HIV-associated lipodystrophy, with measurable reductions in visceral adipose tissue over 26 weeks and maintenance of effect demonstrated across a 52-week extension. The trials also showed a clear, large rise in IGF-1 on treatment, confirming the mechanism.
The honest boundary is the population. The strongest evidence sits specifically in the HIV-lipodystrophy group the drug is approved for. The label itself is explicit that it is not indicated for general weight loss and has a weight-neutral effect overall, it shifts where fat sits rather than dropping total scale weight. The broader uses people are most interested in (general visceral fat, liver fat, cognitive benefit in older adults) are studied but not settled. That line, between the approved, proven use and the popular-but-unproven ones, is the most important thing to keep straight about this compound.
Dosing: the approved dose vs. the research protocol
This is where tesamorelin gets misreported constantly, so it is worth separating cleanly.
The FDA-approved dose (EGRIFTA SV): the approved product is a 2 mg single-dose vial, reconstituted with 0.5 mL of sterile water, from which a 1.4 mg dose (0.35 mL of the reconstituted solution) is injected subcutaneously into the abdomen once daily. That is the actual label: a 0.5 mL reconstitution and a 1.4 mg daily dose, used immediately after mixing and not stored once reconstituted. A newer higher-strength formulation (Egrifta WR, an 11.6 mg vial) uses a 1.28 mg daily dose. The original EGRIFTA formulation and the clinical trials used a 2 mg daily dose; EGRIFTA SV was reformulated so that 1.4 mg delivers comparable drug exposure.
The research-vial protocol: the research-peptide world does not use the 2 mg single-dose pharmaceutical vial. It uses larger research vials, commonly a 10 mg vial, reconstituted with about 3 mL of bacteriostatic water to give roughly 3.33 mg/mL, where 1 unit on a U-100 syringe is about 33 mcg. Within that, reference protocols typically run a 2 mg daily dose (about 60 units), sometimes with a one-week titration at 1 mg to ease tolerability, dosed in the evening to align with the body's natural nighttime GH release.
The key point: the 3 mL reconstitution and the 2 mg daily figure are the research-vial convention, not the FDA-approved numbers. The FDA-approved dose is 1.4 mg from a 0.5 mL reconstitution of a 2 mg vial. Both exist in the literature, but only one is the actual approved protocol, and conflating them is the most common error made about this peptide.
Timeline
Tesamorelin is slow by design. Measurable visceral fat reduction appears around the three to six month mark, which is why the trial protocols and reference cycles run long (commonly 26 weeks, extendable). Anyone expecting the scale to move within a few weeks has the wrong tool; this reshapes a specific fat depot over months rather than driving fast total weight loss.
Side effects and monitoring
The label-documented adverse reactions are real and worth knowing. Injection-site reactions are the most common (erythema, pruritus, pain, irritation, bruising), running notably higher than placebo in trials. Because it raises growth hormone, fluid-retention effects can appear: arthralgia (joint pain), peripheral edema, muscle aches, and carpal-tunnel-type symptoms, which are generally transient or resolve on discontinuation. The metabolic considerations are the important ones: tesamorelin raises IGF-1, and the long-term effects of elevated IGF-1 are not fully known, so IGF-1 should be monitored periodically. It can also cause glucose intolerance, with the trials showing an increased risk of developing diabetes (HbA1c reaching 6.5% or higher) versus placebo, so blood sugar should be evaluated before and during use, especially in anyone with diabetes. It is contraindicated in active malignancy, in pregnancy, in patients with disruption of the hypothalamic-pituitary axis, and in anyone with hypersensitivity to tesamorelin or its excipients.
Storage
For the approved EGRIFTA SV product, the lyophilized 2 mg vial is stored at room temperature (20 to 25 degrees C) and protected from light in its original box, and once reconstituted it is used immediately and not stored, frozen, or refrigerated. For the research-vial protocol using bacteriostatic water, reference handling is to refrigerate the reconstituted solution at 2 to 8 degrees C and use it within about 7 days, avoiding freezing and freeze-thaw cycles. These are genuinely different handling rules because they are different products with different diluents, another reason not to blur the two.
Where it fits
Tesamorelin is the visceral-fat specialist, not a general weight-loss tool, and that distinction is the entire point of the compound. It works by raising the body's own GH and IGF-1, it has real FDA backing for its specific indication, and it is a months-long commitment rather than a fast fix. For the popular off-label use, targeting deep belly fat outside the HIV-lipodystrophy population, it sits in research-context territory rather than approved use, and that honest framing matters. If the problem is specifically stubborn deep belly fat and the timeline expectation is realistic, it is one of the more legitimately evidenced options in this space.