Tesamorelin (formerly TH9507) is a synthetic analog of the full 44-amino acid human growth hormone-releasing hormone (GHRH) modified with a trans-3-hexenoic acid (hexenoyl) group attached to the N-terminal tyrosine residue. This modification confers resistance to enzymatic degradation by dipeptidyl peptidase-4 (DPP-4), extending the peptide's biological half-life while preserving its ability to bind and activate GRF receptors on anterior pituitary somatotroph cells with potency equivalent to endogenous GHRH.
Tesamorelin was approved by the FDA in November 2010 as Egrifta, making it the first and only FDA-approved treatment for excess abdominal fat (lipohypertrophy) in HIV-infected adults with lipodystrophy. An improved formulation, Egrifta SV, simplified reconstitution. In March 2025, the FDA approved Egrifta WR, a new F8 formulation requiring weekly reconstitution instead of daily, significantly reducing patient burden.
Tesamorelin occupies a unique position among growth hormone secretagogues. Unlike synthetic GH (somatropin), which provides exogenous GH directly, tesamorelin stimulates endogenous GH production through the natural GHRH-GH axis. This preserves physiological pulsatile GH release patterns and maintains the hypothalamic-pituitary feedback loop, including IGF-1-mediated negative feedback. This mechanism is considered more physiological than direct GH administration.
Beyond its approved indication, tesamorelin has generated significant interest for body composition optimization, visceral fat reduction, NAFLD/NASH treatment, and cognitive enhancement in aging adults. NIH-funded studies at Massachusetts General Hospital have investigated its effects on hepatic steatosis and cognitive function. However, these off-label applications are not FDA-approved, and the long-term cardiovascular safety of tesamorelin has not been established.
A synthetic analogue of human growth hormone-releasing hormone, approved as Egrifta for the reduction of excess visceral abdominal fat in adults with HIV-associated lipodystrophy. Supplied as a lyophilised powder that is reconstituted before measurement.
| Weeks | Dosage | Syringe units (U-100) |
|---|---|---|
| Weeks 1–26 | 2 mg | 40 units0.4 mL |
| Weeks | Dosage | Syringe units (U-100) |
|---|---|---|
| Weeks 1–26 | 2 mg | 40 units0.4 mL |
FrequencyOnce daily, subcutaneous.
Tesamorelin does not titrate: the Egrifta prescribing information sets one fixed amount of 2 mg once daily, so the single row is the whole schedule rather than the first step of one, and the week span is the 26-week length of the pivotal lipodystrophy trials, which ran a further 26-week extension at the same amount. A later reformulation is dosed at 1.4 mg once daily and is stated to be bioequivalent to the 2 mg original — that is the same delivered exposure in a different formulation, not a lower amount, and it is not the figure charted here. The 5 mg and 10 mg vials both come to 5 mg/mL as made up above, so the 2 mg amount is 40 units on either chart — inside one 50-unit syringe, with the rest of the vial left for later injections, two full amounts from the 5 mg vial and five from the 10 mg one. The approval is narrow — abdominal fat in HIV-associated lipodystrophy — and this amount is not established evidence for body composition, liver fat or cognition in anyone else.
What this evidence establishes. Tesamorelin is FDA-approved, and its dosing comes from a prescribing label. The approval is narrow: reduction of excess visceral abdominal fat in adults with HIV-associated lipodystrophy. The two figures on record are not two dose levels — they are the same delivered dose in two formulations, so the lower number does not mean a lower exposure.
Sources: Egrifta FDA prescribing information · Egrifta SV FDA prescribing information · Phase 2 trials comparing 1 mg and 2 mg doses, 2004–2007
For educational and laboratory research purposes only. It does not provide medical advice, dosing recommendations, or instructions for human or veterinary use. Syringe units assume a U-100 syringe, on which 1 mL is 100 units and a 50-unit syringe holds 0.5 mL.
Tesamorelin binds to GRF receptors on anterior pituitary somatotroph cells, triggering a cascade that produces pulsatile growth hormone release:
Binds pituitary GRF receptors with equivalent potency to endogenous GHRH. Stimulates synthesis and pulsatile release of growth hormone from somatotroph cells.
GH stimulates hepatic IGF-1 production. Clinical trials showed significant IGF-1 increases. Effects of prolonged IGF-1 elevation are under long-term monitoring.
GH is powerfully lipolytic. Tesamorelin reduces visceral adipose tissue (VAT) by 15-18% in clinical trials without affecting subcutaneous fat or extremity fat.
GH is anabolic. Tesamorelin increases lean body mass while decreasing trunk fat. Waist circumference decreases.
NIH-funded studies suggest tesamorelin may improve cognitive function in older adults. GH/IGF-1 axis has documented roles in neuroprotection and neuroplasticity.
Clinical trial data shows tesamorelin reduces liver fat content and prevents fibrosis progression in HIV patients with NAFLD. Phase 2 trial in non-HIV NAFLD underway.
Key pharmacological distinction: Tesamorelin vs. direct GH: Tesamorelin preserves pulsatile GH release and maintains feedback regulation. Direct GH administration bypasses the hypothalamus-pituitary axis, can suppress endogenous production, and produces non-physiological continuous GH levels. Tesamorelin vs. GHRPs (ipamorelin, etc.): Tesamorelin acts through GHRH receptors; GHRPs act through ghrelin/GHS receptors. Tesamorelin has FDA approval and Phase 3 data; no GHRP has completed this regulatory pathway.
Tesamorelin has well-characterized safety data from Phase 3 trials (740+ treated patients) and post-marketing experience:
| Condition / Factor | Risk Level | Rationale |
|---|---|---|
| Active malignancy | CONTRAINDICATED | GH/IGF-1 axis stimulation could promote tumor growth. Discontinue if malignancy recurs. Previous cancer must be inactive with treatment complete. |
| Pituitary disorders / surgery / radiation | CONTRAINDICATED | Disrupted hypothalamic-pituitary axis may produce unpredictable GH response. Not appropriate for patients with pituitary pathology. |
| Pregnancy | CONTRAINDICATED | Animal studies showed hydrocephaly in offspring at ~2x clinical dose. Discontinue immediately if pregnancy occurs. |
| Elevated IGF-1 | MODERATE (monitor) | Tesamorelin elevates IGF-1. Long-term effects of sustained IGF-1 elevation are unknown. Monitor IGF-1 levels during treatment. Dose adjustment or discontinuation may be needed. |
| Diabetes / glucose intolerance | MODERATE | GH increases insulin resistance. Higher rates of diabetes observed in tesamorelin vs. placebo in clinical trials. Monitor blood glucose. |
| Hypersensitivity reactions | MODERATE | Rash, urticaria, and pruritus reported. Anti-tesamorelin antibodies develop in ~50% of patients by 26 weeks. Cross-reactivity to native GHRH in ~60% of antibody-positive patients. |
| Fluid retention / edema | LOW-MODERATE | Arthralgia, extremity pain, peripheral edema, and myalgia are common GH-class effects. Generally mild. |
| Injection site reactions | LOW (common) | Erythema, pruritus, pain, and irritation at injection site. Among most commonly reported adverse events. |
| VAT rebound on discontinuation | EXPECTED | VAT re-accumulates to near baseline levels after discontinuation. Chronic therapy required to maintain reductions. Not a permanent intervention. |
| Long-term CV safety | UNKNOWN | Long-term cardiovascular benefit has not been studied. FDA requires post-marketing observational study for MACE and cancer risk. |
FDA: Tesamorelin is FDA-approved (Nov 2010) for the reduction of excess abdominal fat in HIV-infected adults with lipodystrophy. Brand names: Egrifta (original), Egrifta SV (simplified), Egrifta WR (weekly reconstitution, approved March 2025). Manufactured by Theratechnologies Inc.
Off-Label Use: Tesamorelin is widely prescribed off-label by anti-aging, functional medicine, and hormone optimization practitioners for body composition, visceral fat reduction, metabolic health, and cognitive support. These uses are not FDA-approved. Insurance typically covers only the HIV lipodystrophy indication.
Compounding: Tesamorelin is available through compounding pharmacies at lower cost than the branded product. Compounded versions are commonly used for off-label applications.
Key distinction: Tesamorelin is one of the few peptides in the GH secretagogue space with actual FDA approval and Phase 3 clinical trial data. This gives it a fundamentally different evidence base than research-only compounds like ipamorelin, CJC-1295, or MK-677. Its GHRH mechanism provides more physiological GH release than GHRPs, without prolactin or cortisol increases. The trade-off: effects reverse on discontinuation, and long-term cardiovascular safety is unestablished.
Test your understanding of tesamorelin's GHRH mechanism, clinical evidence, and regulatory status.
This profile is for educational and research purposes only. It is not medical advice, and nothing on it is a protocol, a recommendation, or an instruction for use in a person or an animal.
Athena Peptides Education does not prescribe, sell, or recommend any compound. Compounds discussed here are for laboratory research only and are not for human consumption. Always consult a qualified physician before making any decision about your health.