Tesamorelin vs Sermorelin: differences, evidence and safety

Answer first

Tesamorelin and sermorelin both copy the brain hormone that releases growth hormone and act on the same receptor. Tesamorelin is the full 44-building-block chain, approved in the United States only for belly fat in adults with HIV. Sermorelin is a 29-building-block fragment whose approvals ended in 2009. No direct comparison could be found in the sources reviewed for this page.

At a glance

How they work

Both substances are laboratory-made copies of growth hormone releasing hormone, the brain signal that tells the pituitary gland to release growth hormone. Neither is growth hormone itself.

Tesamorelin

• It carries the full natural chain of 44 amino acid building blocks. A small six-carbon group (a hexenoyl group) at the front end slows its breakdown ^[1].
• It binds to the docking points for this hormone on the pituitary gland. In laboratory tests it does so about as strongly as the natural hormone ^[1].
• The gland then releases growth hormone in its normal pulses. In patients this raised IGF-1, a messenger made mainly in the liver, and its carrier protein IGFBP-3 ^[1].

Sermorelin

• It copies only the first 29 building blocks of the natural hormone, unaltered, with a capped tail end. This is the shortest piece that still carries the full biological activity ^[2].
• It docks onto the same receptor on the growth hormone cells of the front lobe of the pituitary gland ^[2], ^[3].
• Because the signal passes through the gland, the body's own brake, a hormone called somatostatin, keeps working ^[2].

The key difference is therefore not the target but the molecule. Both press the same button in the same hormone chain. Tesamorelin is the whole natural sequence with a protective addition, while sermorelin is the plain front fragment ^[4].

Both leave the blood quickly. Tesamorelin has a half-life of about 11 minutes in healthy adults. It reaches its peak level after a median, or middle value, of 0.15 hours, roughly 9 minutes ^[1]. Sermorelin has a half-life of roughly 10 to 20 minutes, because the kidneys filter it out and enzymes clip its front end ^[5].

What the studies show

No study that compares tesamorelin and sermorelin directly could be found in the published record reviewed for this page. The two were tested in different people, for different purposes, decades apart. What follows are the separate studies of each substance.

Tesamorelin: deep belly fat in people with HIV

Phase 3 RCT The first approval trial randomised 412 adults with HIV and lipodystrophy, a condition in which body fat is redistributed in an unusual way. After 26 weeks the deep fat around the organs had fallen by 15.2 per cent on treatment and risen by 5.0 per cent on placebo (p < 0.001) ^[6].

The official label reports the same result as a difference of 31 square centimetres, or 20 per cent ^[1].

Phase 3 RCT The second trial followed 404 adults for six months. The deep fat fell by 10.9 per cent on treatment, against 0.6 per cent on placebo (p < 0.0001). Fat on the arms and legs did not change, and neither did the fat just under the skin of the belly ^[7].

Meta-analysis Pooling five randomised trials, the difference against placebo averaged 27.71 square centimetres of visceral fat. Body mass index did not change significantly ^[8].

Body weight and fat loss

Phase 3 RCT Tesamorelin changed where fat sits, not how much a person weighs. Average body weight moved by −0.4 kg in the first approval trial and +0.5 kg in the second, neither different from placebo. The label states that the drug is not indicated for weight loss, because its effect on weight is neutral ^[1].

Trials of tesamorelin in obesity without HIV stayed academic and led to no approval anywhere ^[1], ^[9].

Open treatment series For sermorelin, only one study in this record measured body fat. It treated 11 healthy, non-obese men aged 64 to 76 for six weeks. Night-time growth hormone release rose (p < 0.02). Weight, body mass index, the waist-to-hip ratio and the scan measurements of muscle and fat all stayed where they were ^[10].

Sermorelin: growth in children

Open-label multicentre study The study behind the 1997 American approval enrolled 110 previously untreated children before puberty with growth hormone deficiency. Of these, 86 entered the efficacy analysis. Their average growth speed rose from 4.1 centimetres a year to 8.0 after six months, and settled at 7.2 after twelve months ^[11].

At six months, 74 per cent of the children counted as good responders. There was no comparison group ^[11].

Narrative review A 1999 review compared published studies indirectly. It concluded that the gain in growth speed under sermorelin was smaller than under the same amount of growth hormone. No head-to-head trial could be found in the sources reviewed for this page, and the review does not report the effect on final adult height ^[2].

Older adults

Placebo-controlled study For sermorelin, ten women and nine men aged 55 to 71 had four weeks of placebo followed by 16 weeks of active treatment. The release of growth hormone began within 10 minutes and lasted about two hours ^[12].

In the same group, growth hormone secretion rose by 107 per cent in the men and 70 per cent in the women (p < 0.05). IGF-1 rose by 28 per cent (p < 0.001). These are laboratory values, and no clinical benefit was measured ^[13].

Phase 2 RCT For tesamorelin, an academic trial treated 152 adults aged 55 to 87 for 20 weeks, 66 of them with mild cognitive impairment. It found a favourable overall effect on thinking tests (p = 0.03), mainly in planning and mental flexibility. No regulator has approved the drug for anything to do with memory ^[14].

Where the studies fell short

Phase 2 RCT A later tesamorelin trial in 73 people with HIV and abdominal obesity found no cognitive advantage over the comparison group (p = 0.673). The trial was open-label, and its authors call it underpowered ^[15].

Phase 2 RCT In 53 adults with type 2 diabetes, twelve weeks of tesamorelin changed nothing measurable. The insulin response, fasting glucose and long-term blood sugar all stayed the same ^[16].

Open treatment series The earliest sermorelin series treated 18 children, 14 of whom had previously had growth hormone. Four of those 14 grew more slowly, for reasons the authors could not explain ^[17]. In the older men's series, only two of six strength measures improved ^[10].

What happens after stopping

Phase 3 RCT In the tesamorelin extension phase, 263 participants were randomised again for a further 26 weeks. Those who stayed on treatment held the reduction at 18 per cent below their starting point at 52 weeks. Those switched to placebo lost the gains, and the deep fat accumulated again ^[18].

For sermorelin, no comparable study could be found in the sources reviewed for this page. None of these sources reports the height these children eventually reached as adults ^[2].

These results come from different populations, doses, endpoints and study lengths. The figures for tesamorelin and sermorelin therefore cannot be set against each other.

Safety

The two safety records differ mainly in how much is known. Tesamorelin has a current official label drawn from its approval trials. For sermorelin, no product information sheet for either former product is publicly available any more ^[19].

Tesamorelin, from the American label:

• Injection-site reactions in 17 per cent against 6 per cent on placebo over the first 26 weeks, including redness, itching, pain and swelling ^[1].
• Joint pain in 13 per cent against 11 per cent. Muscle pain affected 6 per cent against 2 per cent, and swelling of the ankles and feet 6 per cent against 2 per cent ^[1].
• Higher blood sugar. The odds of developing diabetes were raised (odds ratio 3.3; 1.4 to 9.6) ^[1].
• Raised IGF-1. At 26 weeks, 47 per cent of participants were more than two standard deviations above normal. The label calls the long-term consequences unknown ^[1].
• Antibodies in about half of those treated, 50 per cent at 26 weeks, without a visible change in how well the drug worked ^[1].
• Situations that rule it out entirely: an active cancer, a disrupted link between the hypothalamus and the pituitary gland, a known allergy, and pregnancy ^[1].

Sermorelin, from the published studies:

• Brief facial flushing and pain at the injection site were the most frequently reported events. The review that reports them gives no percentages ^[2].
• Antibodies against the hormone in 14 of 18 children in the 1987 series, with no visible effect on growth or on the response to treatment ^[17].
• Bone age moving faster than height. In children treated after radiotherapy to the head, bone age advanced by 1.1 years per calendar year ^[20].
• Formal contraindications cannot be stated, because no valid product information sheet could be found. The sources reviewed contain no data on pregnancy, breastfeeding, or impaired kidney or liver function ^[19].

Material bought outside a pharmacy carries a separate problem for both substances. Its composition, strength and purity are unverified ^[21].

Why this page lists no doses. Tesamorelin is a prescription medicine, and sermorelin is prescription-only by name in Germany and Australia. Choosing an amount is a matter for a doctor and valid product information. This page therefore reports what the studies measured without repeating the amounts they used.

Legal status

Tesamorelin has been a US prescription medicine since 10 November 2010. Its approval covers only excess belly fat in adults with HIV and lipodystrophy ^[22]. The European application was withdrawn on 21 June 2012; the Canadian product was cancelled on 30 September 2022 ^[9], ^[23]. Sermorelin held American approvals from 1990 and 1997. Its maker stopped selling both in 2008 and asked for their withdrawal, effective 18 June 2009 ^[24], ^[25]. In March 2013 the regulator found that neither was withdrawn for safety or effectiveness reasons ^[26]. No country licenses it now; Germany and Australia list it as prescription-only ^[27], ^[28]. Both are banned in sport at all times, under S2.2.4 of the 2026 list ^[29]. Status: 7 and 10 September 2026.

Used together?

The blend directory lists no product that combines tesamorelin and sermorelin. Tesamorelin appears there only in mixtures with other peptides, such as Tesamorelin + Ipamorelin, and each carries the note that the mixture holds no approval. The full list is under blends.

No study of tesamorelin and sermorelin given together could be found in the sources reviewed for this page. Both act on the same receptor, and none of the sources reviewed describes what the combination does or how safe it is.

Frequently asked questions

Which is better, tesamorelin or sermorelin?

Neither can be ranked, because no study comparing them could be found in the sources reviewed for this page. In adults with HIV and lipodystrophy, tesamorelin reduced deep belly fat by 15.2 per cent over 26 weeks, while it rose by 5.0 per cent on placebo. Sermorelin was studied mainly in children with growth hormone deficiency, whose growth speed rose from 4.1 to 8.0 centimetres a year with no comparison group. The populations, endpoints and designs differ too much for a verdict.

Which is better for fat loss, tesamorelin or sermorelin?

No study comparing tesamorelin and sermorelin on any fat measure could be found in the sources reviewed for this page. Tesamorelin is approved in the United States only to reduce excess deep belly fat in adults with HIV and lipodystrophy. Its label states that it is not indicated for weight loss, because its effect on weight is neutral. Sermorelin's two former approvals covered a pituitary test and growth in children, not body fat.

What is the difference between tesamorelin and sermorelin?

Tesamorelin copies all 44 building blocks of the natural hormone and adds a small group at the front end that slows its breakdown. Sermorelin copies only the first 29 building blocks, unaltered. Legally, tesamorelin is an approved prescription medicine in the United States, while the maker of sermorelin gave up both of its American approvals in 2009.

Is tesamorelin or sermorelin safer?

No study comparing their safety could be found in the sources reviewed for this page, so no ranking is possible. Tesamorelin has an official label with measured frequencies, for example injection-site reactions in 17 per cent against 6 per cent on placebo, and raised odds of diabetes. Sermorelin has no current product information, so its record rests on small, older studies that report flushing and injection-site pain without percentages.

Can tesamorelin and sermorelin be taken together?

No study of the two given together could be found in the sources reviewed for this page, so these sources say nothing about the effect or the safety of the combination. Both act on the same receptor. The blend directory lists no product that contains both.

Are tesamorelin and sermorelin FDA-approved?

Yes for tesamorelin, which has held an American approval since 10 November 2010 for excess belly fat in adults with HIV and lipodystrophy. Sermorelin was approved in 1990 as a diagnostic test and in 1997 for children with growth hormone deficiency, but both approvals ended on 18 June 2009 at the maker's request. In March 2013 the regulator determined that neither product was withdrawn for reasons of safety or effectiveness.

Are tesamorelin and sermorelin banned in sport?

Yes, both at all times, in competition and out of it. The 2026 prohibited list names them together in section S2.2.4 among the growth hormone releasing factors. German anti-doping law names both separately as well.

How long do tesamorelin and sermorelin stay in the body?

Only for minutes. Tesamorelin has a half-life of about 11 minutes in healthy adults, and sermorelin roughly 10 to 20 minutes in human plasma. The added group on tesamorelin slows its breakdown compared with the natural hormone, yet both remain short-lived.

Is sermorelin a shorter version of tesamorelin?

In part. Sermorelin is the front fragment of the natural hormone, building blocks 1 to 29. Tesamorelin carries all 44 building blocks, with a modification at the front end. They share a receptor and a line of the doping list, but they differ in structure and in legal standing.