What is Tesamorelin?

What sources report

Human evidence for tesamorelin is strongest for one narrow use: adults with HIV and excess abdominal fat, studied in two phase 3 trials that pooled 806 people.¹⁰ Outside that group, trials have enrolled 13 to 152 people.¹⁵¹⁸

How it works

Tesamorelin keeps the full 44-amino-acid sequence of human growth hormone-releasing factor and adds a hexenoyl group, a 6-carbon chain with one double bond, at the front.¹ GHRH is a hypothalamic hormone that acts on somatotroph cells in the pituitary, which make growth hormone and release it in pulses; growth hormone has both tissue-building and fat-releasing effects.¹ In lab (in vitro) tests, tesamorelin activates human GHRH receptors with about the same potency as the natural hormone.¹

In people it raises growth hormone, then IGF-1 and IGFBP-3, without clinically significant changes in TSH, LH, ACTH or prolactin.¹ In 13 healthy men given daily injections for two weeks, both baseline and pulsed growth hormone secretion increased.¹⁵ The molecule itself is short-lived: less than 4% of an under-the-skin dose reached the blood with the original formulation, and its mean elimination half-life is about 8 to 11 minutes.¹⁶

What the trials found

Fat under the skin did not change significantly in the pooled analysis, so the effect is on deep abdominal fat.¹⁰ In the label studies, lean body mass rose 1.2 to 1.3 kg from baseline and trunk fat fell 0.8 to 1.0 kg.¹ Gains did not last: when patients were switched to placebo for a second 26 weeks, visceral fat came back and lean body mass fell 1.7 to 1.8 kg.¹¹⁹ In treatment responders (visceral fat down 8% or more), an exploratory analysis of two trials found greater increases in skeletal muscle area and density than on placebo.²⁰

Two 2026 meta-analyses agree on the direction. One, of 4 randomized trials with 909 patients, found significantly less visceral fat, a 1.61 cm smaller waist and 1.42 kg more lean body mass; discontinuations were more common (risk ratio 2.25) but not significantly so (p=0.06), and long-term safety data were limited.²¹ The other, of 5 trials, found 27.71 cm2 less visceral fat but no significant change in fat under the skin or BMI.²²

Cognition results are mixed. After the positive 20-week trial, a 6-month open-label trial in 73 people with HIV found no significant cognitive difference from standard care, and a 10-week placebo-controlled pilot in 22 adults found no significant changes.²³²⁴

What has not been shown

The label rules out weight loss as an indication.¹ None of the 24 registered tesamorelin studies (October 2026) involves athletes, and a 2026 review calls tesamorelin and other growth hormone axis peptides investigational in sports medicine.⁷⁹ A planned phase 2 trial of GHRH for sleep after brain injury was withdrawn before it enrolled anyone, and the 10-week pilot found no change in sleep.⁷²⁴ A phase 2 trial in peripheral nerve injury has been recruiting since 2018, with no results yet.⁷ The goal pages map these searches: Peptides and muscle growth, Peptides and sleep and Peptides and focus and memory.

How it compares

Sermorelin is only the first 29 amino acids of GHRH, with a molar mass near 3358 g/mol against tesamorelin's 5136.^33342526 The CJC-1295 with DAC form lasts far longer, with a half-life of 5.8 to 8.1 days in healthy adults, and FDA notes serious adverse events with CJC-1295, including increased heart rate.²⁷¹² See CJC-1295 No DAC and CJC-1295 with DAC. Unlike HGH, tesamorelin is not growth hormone, and WADA lists the two in separate groups (S2.2.3 for growth hormone, S2.2.4 for releasing factors).⁵ Research vials are listed at Tesamorelin for sale; they are not Egrifta.

Side effects

The label's adverse reaction table lists reactions seen in at least 1% of patients, and more often than on placebo, during the 26-week trial phase, with 543 adults on tesamorelin and 263 on placebo.¹

Label warnings go beyond the table:

• Blood sugar: 5% developed diabetes (HbA1c of 6.5% or higher) versus 1% on placebo, so glucose is checked before and during treatment, and people with diabetes are watched for eye disease (retinopathy).¹
• IGF-1: 47% had IGF-1 above 2 standard deviation scores and 36% above 3 after 26 weeks, which is why levels are monitored.¹
• Fluid retention: swelling, joint pain and carpal tunnel syndrome, which pass or resolve after stopping.¹
• Allergic reactions: 4% of treated patients, including itching, redness, flushing, hives and rash.¹
• Injection sites: in a separate count in the label's warnings, injection site reactions such as redness, itching, pain, irritation and bruising affected 25% of treated patients and 14% on placebo in the first 26 weeks; sites are rotated.¹
• Antibodies: 50% of patients formed antibodies by 26 weeks, about 60% of those also reacted with the body's own GHRH, and responses were similar with or without them.¹
• Cancer: tesamorelin releases growth hormone, a known growth factor, so it is not used with active cancer, and lifetime cancer studies in rodents have not been done.¹ In 2012, EMA's human medicines committee considered high IGF-1, with its possible links to cancer and worsening diabetic eye disease, a major safety concern.²⁸
• Who should not use it: people with a disrupted hypothalamic-pituitary axis (pituitary surgery or tumor, hypopituitarism, head irradiation or trauma), known hypersensitivity to tesamorelin or the product's inactive ingredients, and pregnant women; rats exposed in pregnancy had offspring with hydrocephaly, and mothers using it should not breastfeed.¹
• Other cautions: increased deaths were reported when growth hormone was given in acute critical illness; children with open growth plates may grow excessively; there is no information for people over 65.¹

In the first large trial (412 patients, 26 weeks), adverse events did not differ significantly between groups, but more patients on tesamorelin withdrew because of one.²⁹

Dosage information

The prescriber sets the dose. The FDA labels give one schedule per product, and both cover one use only: reducing excess abdominal fat in HIV-infected adults with lipodystrophy.⁶¹

The labels state that the 1.4 mg and 1.28 mg doses give systemic exposure similar to the original 2 mg dose, yet the Egrifta WR label calls the two newer forms not substitutable.⁶¹ Trials outside the label used 1 mg or 2 mg daily, such as 2 mg for 12 months in obese adults and 1 mg before bedtime for 20 weeks in older adults; those were research protocols, not approved uses.¹³¹⁸ The labels set doses for that one use only, so no dose is established for research-grade vials or any other use, and study doses are not guidance for any person.¹

Reconstitution and storage

Mixing and storage rules exist only for the approved products, and they differ:

• Egrifta SV: 0.5 mL of the supplied Sterile Water for Injection per 2 mg vial, rolled gently in the hands for 30 seconds and not shaken.⁶ The dose is given right after mixing and the rest is thrown away; the mixed solution is not refrigerated or frozen.⁶
• Egrifta WR: 1.3 mL of the supplied Bacteriostatic Water for Injection per 11.6 mg vial (8 mg per mL), swirled and not shaken.¹ The mixed vial stays at 20 to 25 °C (68 to 77 °F) and is discarded 7 days after mixing, never frozen.¹
• Unmixed vials: both are kept at 20 to 25 °C (68 to 77 °F) in the original box to protect them from light.⁶¹
• Inspection: the mixed Egrifta WR solution is clear and colorless, and it is not used if it is cloudy, colored or has particles.¹

The two forms also carry different inactive ingredients: histidine, mannitol, polysorbate 20 and sucrose in Egrifta SV, and hydroxypropyl betadex and mannitol in Egrifta WR.⁶¹ So these steps cannot be assumed to apply to any other product.¹ No published stability or mixing data were found for research-grade vials. Lab handling is covered in How to store peptides, How to reconstitute a peptide vial and the Reconstitution calculator.

Regulatory status

United States

FDA first approved tesamorelin as Egrifta on November 10, 2010, and it remains a prescription medicine with one approved use.⁴¹ The labels cited here are Egrifta SV (revised February 2024) and Egrifta WR (revised March 2025).⁶¹ Its application was deemed a biologics license application (BLA 022505) on March 23, 2020, and FDA says biological products subject to licensure are not eligible for the 503A and 503B compounding exemptions.⁴³⁰ Tesamorelin is not on FDA's list of bulk substances that may present significant safety risks (page current as of April 22, 2026).¹²

On August 24, 2026, FDA warning letters to two online peptide sellers named tesamorelin products among unapproved new drugs, including a "Tesamorelin Research Peptide" and a "Tesamorelin Ipamorelin Blend".³¹³² FDA said "for research use only" labels did not change that: the website's own claims, plus bacteriostatic water sold alongside a "peptide guide" and "peptide calculator", showed the products were meant for people.³²

Europe and sport

Ferrer Internacional withdrew its EU application for Egrifta on June 21, 2012.²⁸ At that point EMA's human medicines committee held the provisional opinion that it could not have been approved, partly because lipodystrophy fat is hard to tell apart from obesity fat in practice.²⁸ WADA's 2026 Prohibited List, in force from January 1, 2026, names tesamorelin under S2.2.4, and class S2 substances are banned at all times, in and out of competition.⁵