The short version

Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.

What Tesamorelin is

Tesamorelin is a synthetic analogue of human growth-hormone-releasing hormone — the full 44-amino-acid GHRH sequence with a trans-3-hexenoyl group attached to the N-terminus. That one modification is the whole point of the molecule: native GHRH is degraded in plasma within minutes, and the added group slows that degradation enough to make a once-daily subcutaneous injection viable.

It is sold as a pharmaceutical under the name EGRIFTA, approved in the United States in 2010 to reduce excess visceral abdominal fat in people with HIV-associated lipodystrophy. It remains one of only a handful of compounds in this library that has an approved human label rather than a literature of animal work and community convention.

How it works

Tesamorelin binds the GHRH receptor on somatotroph cells in the anterior pituitary. Receptor activation drives synthesis and pulsatile release of endogenous growth hormone, which in turn raises hepatic production of IGF-1. Essentially every downstream effect attributed to Tesamorelin is an effect of that growth hormone pulse, not of the peptide itself.

Why that distinction matters

Because release is pituitary-mediated, it stays subject to normal feedback. Somatostatin tone and IGF-1 negative feedback both still operate, which is the mechanistic argument for a secretagogue producing a more physiological profile than exogenous growth hormone. That is an argument about mechanism, not a demonstrated clinical advantage, and it should be read as the former.

The corollary is that Tesamorelin does nothing without a functioning hypothalamic-pituitary axis. Disruption of that axis is an explicit contraindication on the approved label.

Pharmacokinetics

The number that surprises people: the mean elimination half-life after a 1.4 mg subcutaneous dose in healthy subjects is 8 minutes. Clearance is faster still in people with HIV. That is not a typo and it is not a problem — the peptide only has to survive long enough to trigger a pituitary pulse, and the pulse outlasts the peptide by a wide margin.

There is no published oral, intranasal or transdermal bioavailability figure for Tesamorelin worth quoting. Products claiming those routes are not supported by the label.

What the evidence shows

This is the strongest evidence base in the metabolic section of our catalogue, and it is worth being precise about what it actually demonstrated.

The pivotal trials

Two randomised placebo-controlled trials in people with HIV-associated abdominal fat accumulation measured visceral adipose tissue by CT at 26 weeks:

What it did not show

The endpoint was visceral fat measured on imaging in a specific population. It was not subcutaneous fat, not body weight, not lean mass, not athletic performance, and not longevity. A separate trial in obese subjects without HIV reported roughly an 8% decrease in visceral fat against an 11% increase on placebo over twelve months — directionally consistent, but a different population and a smaller effect.

Reconstitution

The approved 2 mg vial is reconstituted with 0.5 mL of diluent, giving 2 mg per 0.5 mL, and the labelled 1.4 mg dose is drawn as 0.35 mL. That arithmetic is on the label and it is a useful sanity check, but it describes a single-dose pharmaceutical vial.

A 20 mg research vial

Worked at the volumes people actually use, so you can check it rather than take it:

★ 2 mL is the Sentient house standard for this vial, giving 10 mg/mL — one unit is 100 mcg, so the arithmetic stays simple. Note the vial itself holds 3 mL, so volumes above that will not physically fit however the calculator arithmetic works out. 20 mg ÷ 2 mL = 10 mg/mL. At U-100, one unit is 0.01 mL, so one unit carries 10 mg/mL × 0.01 mL = 0.1 mg = 100 mcg. A 2 mg draw is therefore 20 units. The calculator will do this for any volume you choose.

Direct the stream down the inside wall of the vial rather than onto the cake, swirl rather than shake, and label the vial with the resulting concentration — not the volume you added. The full method is in the reconstitution guide.

Reported protocols

One figure here is trial-derived. Everything else in circulation is convention. The difference is the most important thing on this page.

Storage

The approved label stores the lyophilised 2 mg vial at up to 25 °C and instructs that the reconstituted solution be used immediately and not refrigerated or frozen — because it is a single-dose presentation with no preservative.

A 20 mg multi-draw research vial reconstituted in bacteriostatic water is a different object, and the label's guidance does not carry over. The handling conventions in our storage guide apply instead. Those are conventions, not published stability studies for this compound, and we label them as such.

Reported effects

From the approved label and its post-marketing experience:

• Injection-site reactions, itching and erythema — the most commonly reported
• Arthralgia and myalgia
• Peripheral oedema
• Glucose intolerance and new-onset diabetes, reported as uncommon but real
• Elevated serum IGF-1, which the label recommends monitoring

Contraindications on the approved label

• Disruption of the hypothalamic-pituitary axis
• Active malignancy
• Known hypersensitivity to Tesamorelin or mannitol
• Pregnancy

The malignancy contraindication follows from mechanism rather than from an observed signal: the compound raises growth hormone and IGF-1, and IGF-1 is mitogenic. That is a reason for caution that does not depend on a trial having found harm.

Regulatory status

United States. Approved as EGRIFTA (2010) and EGRIFTA SV, prescription only, for HIV-associated lipodystrophy.

Canada. Tesamorelin is a prescription drug. It is not approved for sale as a supplement or a research chemical, and nothing on this page should be read as suggesting otherwise.

Sport. Growth hormone secretagogues, including GHRH analogues, are prohibited at all times under the WADA class S2. Anyone subject to testing should treat this compound as prohibited.

Sentient Biogenix supplies Tesamorelin for laboratory research use only. It is not for human or veterinary use.

Questions we actually get

Is this the same molecule as EGRIFTA?

The peptide is the same. The presentation is not: EGRIFTA is a single-dose 1.4 mg or 2 mg pharmaceutical vial with its own diluent and its own stability data. This is a 20 mg research vial. Treat the label as evidence about the molecule, not as instructions for this vial.

Why does an 8-minute half-life work for once-daily use?

Because the peptide is a trigger, not the active agent. It provokes a growth hormone pulse from the pituitary and is then cleared; the pulse and the IGF-1 response it produces last far longer than the peptide does.

Does it reduce subcutaneous fat too?

The trials measured visceral adipose tissue on CT. They were not designed to answer the subcutaneous question, and we are not going to answer it for them.

Is the 20 mg vial four doses or fourteen?

At the labelled 1.4 mg it is about fourteen; at 2 mg it is ten. That is arithmetic, not a recommendation — see the calculator.

References

1. EGRIFTA SV (Tesamorelin for injection) prescribing information, US FDA, 2019. accessdata.fda.gov — molecular weight, amino acid count, 8-minute half-life, reconstitution volumes, storage, contraindications.
2. EGRIFTA prescribing information, US FDA, 2019. accessdata.fda.gov
3. Tesamorelin. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases. ncbi.nlm.nih.gov — mechanism, approval year, trial visceral-fat percentages, adverse effects.

Every figure on this page traces to one of the three sources above. Where a number in circulation has no primary source behind it, this page says so rather than repeating it.