Tesamorelin peptide: benefits, dosage, side effects and how it compares

Tesamorelin is a synthetic copy of the full 44-amino-acid human growth hormone-releasing hormone, GHRH(1-44), with one change: a short six-carbon hexenoyl chain attached to the first amino acid (tyrosine). The US prescribing information describes it in exactly these terms and gives a molecular weight of 5,135.9 Da for the free base ^[1]. The modification is intended to make the molecule more resistant to enzymatic breakdown than native GHRH while leaving its receptor activity intact.

It was developed by the Canadian company Theratechnologies under the code TH9507, and it is a licensed treatment in the US. That makes it different from related peptides such as sermorelin, whose licence lapsed in 2009, and CJC-1295, which never completed development.

Research-peptide suppliers also sell tesamorelin in vials labelled for laboratory use. Those products are not the licensed medicine, have not been assessed by any regulator, and their content depends entirely on the supplier; see what research peptides are.

Tesamorelin binds the GHRH receptor on somatotroph cells in the anterior pituitary, the same receptor used by the body’s own GHRH. That prompts the pituitary to release growth hormone (GH) in its natural pulses, and GH in turn raises insulin-like growth factor 1 (IGF-1), mostly made in the liver. In the first phase 3 trial, IGF-1 rose by 81% on average over 26 weeks with tesamorelin, compared with a 5% fall on placebo ^[2].

Because it acts upstream of the pituitary, tesamorelin still depends on the normal feedback system (somatostatin and IGF-1 can damp its effect). This is the main theoretical difference from injecting growth hormone itself. GH is lipolytic, and visceral fat appears to be particularly responsive, which is the basis for its licensed use in HIV-associated central fat gain.

So the short answer to how tesamorelin works is indirect: it does not burn fat itself, but raises the body’s own growth hormone output. The tesamorelin mechanism of action also explains why its effects depend on a working pituitary, and why the label rules it out in people whose hypothalamus or pituitary has been disrupted by surgery, radiation or head injury ^[1].

The GHRH route is separate from the ghrelin-receptor route used by ipamorelin, GHRP-2 and GHRP-6. The two pathways add together, which is why GHRH analogues and ghrelin mimetics are often discussed as a pair, though tesamorelin itself has not been studied in combination with them.

The pivotal evidence comes from two multicentre, double-blind phase 3 trials in people with HIV on antiretroviral therapy who had accumulated abdominal fat. In the first, published in the New England Journal of Medicine, 412 patients were randomised to 2 mg tesamorelin or placebo daily for 26 weeks. Visceral fat measured by CT fell by 15.2% with tesamorelin and rose by 5.0% with placebo; triglycerides and the total-to-HDL cholesterol ratio also improved, with no significant difference in glucose measures ^[2].

A pooled analysis of both phase 3 trials (806 patients) found a treatment effect on visceral fat of about -15% at 26 weeks, with no significant change in subcutaneous abdominal fat, improvements in triglycerides and in patient-rated belly appearance, and no clinically meaningful change in glucose over 52 weeks ^[3]. In the extension phase of the first trial, the fall in visceral fat was sustained at -18% over 52 weeks of treatment, but it reaccumulated when tesamorelin was stopped ^[4]. In other words, the effect lasts only as long as treatment does.

A 2026 meta-analysis of five randomised placebo-controlled trials in HIV lipodystrophy confirmed reductions in visceral fat, liver fat and waist circumference and an increase in lean body mass, with no significant change in BMI, subcutaneous fat or CD4 count; adverse events included joint and muscle pain, tingling and injection-site redness ^[5].

Because visceral fat and liver fat tend to travel together, tesamorelin has been tested in HIV-associated fatty liver. In a 50-person randomised trial at Massachusetts General Hospital, six months of 2 mg daily reduced both visceral fat and liver fat compared with placebo; fasting glucose rose slightly at two weeks but the difference had disappeared by six months ^[6].

A larger follow-up, a 12-month randomised double-blind trial of 61 people with HIV and non-alcoholic fatty liver disease published in Lancet HIV, found a 37% relative reduction in liver fat fraction versus placebo; 35% of the tesamorelin group and 4% of the placebo group ended with liver fat below the 5% threshold ^[7]. The authors described the result as promising but said longer studies of liver histology are needed. Neither liver indication is licensed.

The benefits of tesamorelin that are backed by randomised trials are narrow: less visceral fat, lower liver fat and modestly better triglycerides in people with HIV ^[2][3][7]. On the label’s own figures, visceral fat fell by 18% and 14% in the two phase 3 trials against a 2% rise and a 2% fall on placebo, while body weight barely changed; waist circumference fell by about 1 to 2 cm more than placebo ^[1]. The label says it is not indicated for weight loss because its effect on weight is neutral ^[1].

Searches often ask whether tesamorelin helps build muscle. In the phase 3 trials lean body mass rose by about 1.2 to 1.3 kg more than on placebo ^[1], and a secondary analysis found that people whose visceral fat responded to tesamorelin also gained trunk muscle area and lost fat inside the muscle ^[16]. These are small changes in people with HIV, measured over six to twelve months, not a bodybuilding effect. No trial has tested tesamorelin for muscle growth in healthy people or athletes, and it is banned in sport ^[11]. A trial now under way is testing it with exercise in 100 older adults with HIV, with physical function as the goal ^[17].

Most phase 3 participants were men (86% and 84%) ^[1], so evidence for tesamorelin in women is thinner. The cognition trial in older adults included both sexes ^[8], and a 12-month trial in obese men and women without HIV who had low growth hormone found that tesamorelin roughly doubled IGF-1 and improved a measure of muscle energy recovery ^[18]. The label contraindicates it in pregnancy, because visceral fat normally rises in pregnancy and reducing it has no benefit there ^[1].

The trials measured their main result at 26 weeks, and the visceral fat reduction was already clear then ^[2]. Among those who continued for a full year, the effect held, but it reversed once treatment was stopped ^[4]. The label advises considering stopping in people who develop glucose intolerance or diabetes without a clear response ^[1]. There are no trial data at one month.

Tesamorelin before and after photos, for men or women, therefore need care. Visceral fat sits around the organs and is measured by CT or MRI, not by eye, and the trials found no significant change in the fat under the skin that photos show ^[3]. Online pictures rarely say what product, dose or diet was involved, and a research vial is not the tested medicine.

Outside HIV, the best-known study is a 20-week randomised placebo-controlled trial in 152 adults aged 55 to 87, including 66 with mild cognitive impairment. Participants injected 1 mg tesamorelin nightly. The GHRH group showed a favourable effect on a composite cognitive score, driven mainly by executive function, alongside a 117% rise in IGF-1 and a 7.4% fall in body fat; adverse events, mostly mild, were reported by 68% on tesamorelin and 36% on placebo ^[8].

A later open-label phase 2 trial in 73 people with HIV, abdominal obesity and neurocognitive impairment found that tesamorelin reduced waist circumference but did not improve cognition more than standard care over six months ^[9]. The evidence for cognitive effects is therefore mixed, and there is no licensed cognitive use.

Tesamorelin has also been tested in people with type 2 diabetes, a group in whom raising GH could in theory worsen glucose control. In a 12-week randomised trial of 53 patients, neither 1 mg nor 2 mg daily changed insulin response, fasting glucose or HbA1c compared with placebo ^[10].

Tesamorelin has one of the strongest human evidence bases of any peptide covered on this site: two phase 3 RCTs with more than 800 participants between them ^[2][3], long-term extension data ^[4], a meta-analysis of randomised trials ^[5], and several smaller investigator-led RCTs in liver fat, diabetes and cognition ^{[6][7][8][10]}.

The limits are equally clear. Almost all of the efficacy data come from people with HIV on antiretroviral therapy, the fat reduction reverses when treatment stops, and long-term cardiovascular outcomes have not been established; the US label states this directly ^[1]. There is no good evidence on its use by healthy people for body composition, and it is not licensed for weight loss.

Both are GHRH analogues that act on the same pituitary receptor, but they are not interchangeable. Tesamorelin is the full 44-amino-acid hormone with a stabilising hexenoyl group, and it has phase 3 randomised trial evidence and a current licence for HIV-associated abdominal fat ^[1][2]. Sermorelin is the shorter, unmodified 1-29 fragment; it was licensed in the US as Geref for diagnosing and treating growth hormone deficiency in children, but the manufacturer discontinued it in 2008, and its adult evidence consists of small, short studies. No trial has compared the two head to head, so claims that one is “stronger” or “better” are not supported by direct evidence. Our Tesamorelin vs sermorelin comparison sets the two side by side.

The practical differences follow from their structure. The hexenoyl group gives tesamorelin some protection from the enzyme that inactivates GHRH, but it is still short-lived: the label gives an elimination half-life of 8 minutes for Egrifta SV and 11 minutes for Egrifta WR in healthy adults ^[1][12]. The unmodified sermorelin fragment disappears from the blood in about 4 minutes when infused into a vein ^[19]. Both work by triggering growth hormone pulses that last longer than the drug itself, and both were given as a daily injection under the skin in their licensed forms.

The evidence bases are very different in size and purpose. Tesamorelin’s rests on two phase 3 trials of about 800 adults with a defined outcome, visceral fat, plus later trials in liver fat and cognition ^[2][3][7][8]. Sermorelin’s licensed evidence was in children with growth hormone deficiency, and its adult data are small studies from the 1990s. A 2026 review sorted growth hormone-axis peptides, including both of these, into tiers of evidence running from regulatory-grade randomised trials down to no human studies at all ^[20]. Of the two, only tesamorelin has phase 3 trials behind a current licence ^[1].

People also ask whether tesamorelin and sermorelin can be taken together. Because they act on the same receptor, combining them would not add a second mechanism, and no study has tested the pair. Both are named together on the WADA list as GHRH analogues ^[11].

Ipamorelin works on a different receptor. It is a five-amino-acid ghrelin mimetic that acts on the growth hormone secretagogue receptor, and in animal studies it released growth hormone without the rise in ACTH and cortisol seen with older GHRPs ^[21]. In healthy volunteers its half-life was about 2 hours ^[22]. It has never been approved: its most advanced trial, a phase 2 study in 117 patients with bowel surgery, found no significant benefit for postoperative ileus ^[23]. Tesamorelin, by contrast, is approved and has phase 3 evidence. Our Tesamorelin vs ipamorelin comparison sets the two side by side.

Tesamorelin ipamorelin blends are sold on the idea that the GHRH and ghrelin pathways add together. That idea has some basis: an early study in healthy men found that a GHRP and GHRH given together released more growth hormone than either alone ^[24]. But that study used different peptides, and no study has tested tesamorelin with ipamorelin, in any dose or as a two- or three-peptide blend. So there is no published tesamorelin ipamorelin dosage. The FDA’s August 2026 warning letter to Royal Peptides covered tesamorelin and ipamorelin blends sold with “research use only” labels ^[25].

CJC-1295 is also a GHRH analogue, but it was built to last: in healthy adults its half-life was 5.8 to 8.1 days, and single injections raised growth hormone and IGF-1 for a week or more ^[26]. Tesamorelin lasts minutes and is given daily ^[1]. CJC-1295 never completed development, so only tesamorelin has phase 3 data and a licence. Comparisons of tesamorelin with a CJC-1295 and ipamorelin combination have not been studied.

Growth hormone (somatropin) acts directly on tissues and bypasses the pituitary. Tesamorelin works one step earlier and raises the body’s own growth hormone, so the normal brakes on release still apply ^[1]. In the UK, somatropin is a Class C controlled drug, while tesamorelin is not named in that schedule ^[27]. The two have not been compared in a trial, and tesamorelin’s trials report IGF-1 rises that were large enough to prompt the label to advise monitoring ^[1].

Retatrutide is an experimental weight-loss drug that is not approved in the US ^[28]. Tesamorelin is approved, but for visceral fat in HIV, and its label describes its effect on weight as neutral ^[1]. They are aimed at different outcomes, work through different hormones, and have not been studied together, so nothing is known about taking tesamorelin and retatrutide at the same time.

The phase 3 trials, the liver-fat trials and the Lancet HIV study all used 2 mg tesamorelin injected under the skin once daily ^[2][3][6][7]. The cognition trial in older adults used 1 mg once daily at bedtime ^[8], and the diabetes safety trial compared 1 mg and 2 mg daily ^[10].

The currently marketed US formulation, Egrifta WR, is more concentrated and its labelled dose is 1.28 mg once daily; the label notes that it and the older Egrifta SV formulation differ in dosage and are not substitutable ^[1]. These figures describe what trials and the licensed product use; they are not a recommendation. If you are working out concentrations for laboratory purposes, our peptide calculator shows the arithmetic.

The label gives the details that searches about how to take tesamorelin ask for. Egrifta WR comes as an 11.6 mg vial mixed with 1.3 mL of bacteriostatic water, giving 8 mg per mL, and the 1.28 mg dose is 0.16 mL, injected under the skin of the abdomen once a day ^[1]. Egrifta SV comes as a 2 mg vial mixed with 0.5 mL of sterile water, and the 1.4 mg dose is 0.35 mL ^[12]. The label says to rotate injection sites and avoid scar tissue, bruises and the navel ^[1]. It does not state a time of day; the cognition trial gave it at bedtime ^[8].

Tesamorelin dosage charts for bodybuilding, fat loss, men or women, and cycles of set lengths, do not come from these sources. The trials gave the same daily dose throughout and did not test cycling; the effect wore off after stopping ^[4]. Questions about research vials are arithmetic: a 10 mg vial mixed with 2 mL gives 5 mg per mL, or 0.05 mg in each unit on a U-100 insulin syringe. See our guide to bacteriostatic water for the diluent.

Tesamorelin’s half-life is short: about 8 minutes for Egrifta SV and 11 minutes for Egrifta WR, with peak levels roughly 9 minutes after injection ^[1][12]. So tesamorelin itself stays in your system for well under an hour, though its effect on IGF-1 builds over weeks. The label reports that less than 4% of an injected dose reaches the blood ^[1].

Both licensed forms are injections from vials. We found no approved or studied tesamorelin tablets, pills, oral drops or nasal spray. No data on absorption by mouth or through the nose have been published. Products sold as pens or oral forms are not the licensed medicine.

Whether tesamorelin needs to be refrigerated depends on the product. Egrifta WR vials are kept at room temperature, must not be refrigerated or frozen once mixed, and are discarded seven days after mixing ^[1]. For Egrifta SV, the label says to use the mixed solution straight away and not to refrigerate it ^[12].

In the licensed product’s trials, the most common adverse reactions (reported by more than 5% of patients) were joint pain, injection-site redness and itching, pain in the extremities, swelling of the lower limbs and muscle pain ^[1]. More patients on tesamorelin than placebo withdrew because of adverse events in the first phase 3 trial, although overall adverse-event rates did not differ significantly ^[2].

The US label lists warnings that follow from raising GH and IGF-1: fluid retention (including oedema, joint pain and carpal tunnel syndrome), glucose intolerance or diabetes, hypersensitivity reactions, and a theoretical increased risk of cancer growth, so it is contraindicated in active malignancy. It is also contraindicated in pregnancy and in people with disrupted pituitary function, and IGF-1 monitoring is advised ^[1].

The label’s numbers give a sense of scale for tesamorelin side effects. Injection-site reactions occurred in 25% of people on tesamorelin against 14% on placebo, and hypersensitivity reactions such as rash, itching and flushing in 4% ^[1]. At 26 weeks, 47% had IGF-1 above the normal range by more than two standard deviations and 36% by more than three ^[1]. Diabetes, defined as HbA1c of 6.5% or more, developed in 5% against 1% on placebo, and about half of those treated developed antibodies to tesamorelin by 26 weeks ^[1]. Fluid retention, which can show as swelling, joint pain or carpal tunnel syndrome, is a listed warning ^[1]. Increased appetite is not among the common reactions the label lists.

On cancer, the label does not say tesamorelin causes it, but it rules it out in active malignancy and warns that raised growth hormone and IGF-1 could speed the growth of existing tumours ^[1]. The EMA’s committee named this as a concern and noted the lack of long-term data ^[14]. So whether tesamorelin raises cancer risk over years is unknown. Whether tesamorelin is safe to use without a prescription cannot be answered from the evidence, which covers the licensed product under medical supervision, with IGF-1 and glucose checks.

The tesamorelin peptide is not a steroid; it is an analogue of a natural hormone. Searches ask whether it increases testosterone. The label reports no clinically significant changes in other pituitary hormones, including luteinising hormone, which drives testosterone production ^[1], and we found no trial showing a rise in testosterone.

None of this safety information applies automatically to unlicensed research-grade material, where purity, peptide content and sterility are unknown unless independently tested.

The US FDA approved tesamorelin (Egrifta) in 2010 for reducing excess abdominal fat in adults with HIV and lipodystrophy ^[1]. A more concentrated formulation, Egrifta WR, was approved in March 2025 and became available in September 2025, according to the manufacturer. The FDA’s records list it under biologics licence application 022505, with the new formulation approved on 25 March 2025 ^[13]. In the US it is a prescription-only medicine. Health Canada approved Egrifta in April 2014, but its Drug Product Database now lists both Egrifta products as cancelled, the marketed one since September 2022, so it is no longer a current Canadian licence ^[15].

In Europe, the marketing application was withdrawn in June 2012 after the EMA’s medicines committee indicated it could not conclude that the benefit-risk balance was positive, citing doubts that the fat reduction translated into meaningful health benefits ^[14]. The committee also regarded the rise in IGF-1 seen in many patients as a major safety concern, because of a possible link with cancer and diabetic eye disease, and noted that no long-term safety data had been provided ^[14]. As far as we could confirm, tesamorelin is not a licensed medicine in the UK, Australia or New Zealand. Rules on buying peptides differ by country; see our legal status overview and the US page.

New Zealand’s Medsafe classifies tesamorelin as a prescription medicine ^[29]. Australia’s June 2026 Poisons Standard does not name tesamorelin, though it may fall within the class entry for growth hormone-releasing hormones, which sits in Schedule 4 with Appendix D controls ^[30]. See our Australian legal status page. In the US, the FDA’s warning letters in 2026 have targeted firms selling tesamorelin as a research chemical ^[25].

Tesamorelin is named on the World Anti-Doping Agency Prohibited List under S2 (growth hormone releasing factors) and is banned in and out of competition ^[11].

The licensed Egrifta WR vials are stored at room temperature (20–25°C), protected from light and not frozen; once mixed with the supplied bacteriostatic water, a vial is used for seven days and then discarded ^[1]. Those instructions apply to that specific formulation only.

Research-grade tesamorelin is a different product with no validated stability data. General practice for freeze-dried peptides is covered in our guide to storing peptides.

Tesamorelin is one of the more expensive research peptides because of its size. If you are comparing suppliers, compare prices on a per-milligram basis, check the certificate of analysis using our guide on how to read a COA, and favour third-party tested suppliers.

Tesamorelin cost depends heavily on whether it is the prescription medicine or a research product, and on vial size. Our UK tesamorelin prices and Australian prices pages track research listings by country, and how peptide prices work explains why per-milligram prices vary. A cheap vial with no independent test result is not a like-for-like saving.