Tesamorelin vs CJC-1295: Two Answers to the Same Problem

The brain’s own growth hormone releasing hormone has one big weakness as a research tool: it barely lasts. Within minutes of entering the bloodstream, an enzyme clips off its first two amino acids and switches it off. For decades, researchers who wanted to study what happens when the growth hormone system is stimulated for longer had to work around that problem.

Tesamorelin and CJC-1295 are two of the cleverest answers. Both are built from growth hormone releasing hormone (GHRH). Both act on the same receptor. But they solve the short-life problem in completely different ways: one adds a small protective cap, the other hitches a ride on the most common protein in blood. Those different solutions give them very different profiles in research. This guide explains how each was built, what the key studies found, and where each one fits. Tesamorelin and CJC-1295 are supplied by Crown Peptides strictly for laboratory research use only, and everything below is written for readers interested in the science.

The Problem Both Molecules Were Built to Solve

Natural GHRH is a 44-amino-acid peptide made in the hypothalamus. It travels to the pituitary gland and tells somatotroph cells to release growth hormone in pulses. Growth hormone then drives production of IGF-1, mostly in the liver, which carries out many of its effects.

The weakness lies in GHRH’s first two amino acids, tyrosine and alanine. An enzyme called dipeptidyl peptidase-4 (DPP-4), which is everywhere in the blood, recognises that pair and cuts it off. Without those two residues the hormone no longer activates its receptor properly. The result is a half-life measured in minutes, which is fine for the body but a real limitation for anyone trying to study sustained stimulation.

There are two broad ways to fix that. You can protect the vulnerable front end so DPP-4 cannot cut it, or you can attach the molecule to something large so it stays in circulation far longer. Tesamorelin takes the first route. CJC-1295 with DAC takes the second.

Why visceral fat became the target

Not all fat behaves the same way. Fat under the skin is mostly storage. Visceral fat, the deep fat packed around the abdominal organs, is far more metabolically active and is much more closely linked to problems with blood sugar and blood fats. Growth hormone was already known to reduce visceral fat, but giving growth hormone itself bypasses the body’s own control system. The idea behind a GHRH analogue was to raise growth hormone the natural way, through the pituitary, so that the normal feedback loops stay in charge. In the trials that followed, visceral fat was measured precisely by CT scan, using a single slice at the level of the lower spine, which is why the results can be quoted to a decimal place.

A Montreal story, twice

Here is a detail that rarely gets mentioned. Both molecules came out of Montreal. Tesamorelin was developed by Theratechnologies, and CJC-1295 by ConjuChem, a company built around the idea of attaching drugs to albumin. Two teams in the same city looked at the same weakness in the same hormone and came up with opposite answers: keep the whole hormone and protect its weak point, or shrink it to the working core, toughen it and give it a carrier. Following those two decisions explains almost every difference between the compounds.

Tesamorelin: The Full Hormone With a Protective Cap

Tesamorelin keeps all 44 amino acids of human GHRH. The only change is a small chemical group, a trans-3-hexenoyl group, attached to the very first amino acid. That cap stops DPP-4 from recognising and clipping the front of the molecule, while leaving the rest of the hormone exactly as nature made it.

The effect on half-life is real but modest. Tesamorelin still lasts well under an hour in the bloodstream. That makes it a stabilised version of the natural hormone rather than a long-acting one. It produces growth hormone pulses that look broadly natural, just more reliably.

The trial that made it a medicine

Tesamorelin was developed by the Canadian company Theratechnologies to tackle a specific problem: the build-up of deep abdominal fat in some people treated for HIV. In a trial published in the New England Journal of Medicine, 412 patients with HIV and excess abdominal fat received daily Tesamorelin or placebo for 26 weeks. Visceral fat fell by 15.2% with Tesamorelin and rose by 5.0% with placebo. Triglycerides and the ratio of total to HDL cholesterol also improved, and IGF-1 rose by 81% (PMID: 18057338). Tesamorelin was approved in the United States in 2010 under the name Egrifta for that use.

A newer formulation

The original approval was not the end of Tesamorelin’s development. In March 2025 the US Food and Drug Administration approved a newer, more concentrated formulation, sold as Egrifta WR, for the same use. A new formulation of an existing medicine is a sign that a compound remains clinically active and commercially supported years after its first approval.

Liver fat

A later randomised trial at Massachusetts General Hospital, published in JAMA, looked at 50 patients with HIV over six months. Tesamorelin reduced visceral fat by a net 42 square centimetres compared with placebo and reduced liver fat by a net 2.9 percentage points. Fasting glucose rose slightly at two weeks, but that change did not persist to six months (PMID: 25038357).

A year in the liver

The same group then ran a one-year trial in people with HIV and fatty liver disease. Tesamorelin reduced liver fat and prevented progression of fibrosis, the scarring that drives long-term liver damage. Using paired liver biopsies from that trial, the researchers then looked at which genes Tesamorelin had changed. It increased gene sets involved in oxidative phosphorylation, the energy-producing machinery of the cell, and decreased gene sets involved in inflammation and tissue repair. Those shifts tracked with improvements in a fibrosis gene score (PMID: 32701508). The authors described Tesamorelin as the first strategy shown to be effective against fatty liver disease in people living with HIV.

The brain

Tesamorelin has also been studied beyond fat. In a randomised trial of 152 adults aged 55 to 87, including 66 with mild cognitive impairment, participants received Tesamorelin or placebo nightly for 20 weeks. The researchers reported favourable effects on executive function, the set of mental skills used for planning and switching between tasks (PMID: 22869065). For the full Tesamorelin story, see our Tesamorelin research guide.

CJC-1295: The Fragment That Rides on Albumin

CJC-1295 takes the opposite approach. Instead of the full 44 amino acids, it starts from the shorter active fragment, the first 29 amino acids of GHRH, the same core that Sermorelin is based on. Four of those amino acids are swapped for more stable alternatives to resist enzymes. That modified fragment on its own is often called CJC-1295 without DAC.

The version with DAC (drug affinity complex) adds a reactive linker to the end of the chain. After injection, that linker forms a permanent bond with albumin, the most abundant protein in blood plasma. Albumin circulates for weeks, and while CJC-1295 is attached to it, it is protected from both enzymes and the kidneys.

Why albumin?

ConjuChem’s whole platform was built on one clever observation. Albumin is the most abundant protein in blood, and it lasts a remarkably long time, with a half-life of around three weeks. It is also too large to be filtered out by the kidneys. Anything that hitches a ride on albumin borrows some of that staying power. The company called its approach Drug Affinity Complex, or DAC: a small reactive linker attached to a drug that bonds to albumin once the drug enters the bloodstream. CJC-1295 is the best known product of that idea. Instead of a peptide that disappears within minutes, the result is one that circulates for days while still being able to reach the pituitary and switch on the GHRH receptor. It is a neat example of solving a biological problem by borrowing a solution the body already uses.

That design choice also explains the name researchers use for the two versions. “With DAC” means the albumin-binding linker is attached. “Without DAC”, also called Modified GRF (1-29), is the same toughened 29-amino-acid chain without the linker, so it lasts far longer than Sermorelin but still nowhere near as long as the albumin-bound form.

Days, not minutes

The change is dramatic. In a study of healthy adults published in the Journal of Clinical Endocrinology and Metabolism, a single injection of CJC-1295 raised mean growth hormone levels two- to ten-fold for six days or more, and raised IGF-1 1.5- to three-fold for nine to eleven days. The estimated half-life was 5.8 to 8.1 days. With repeated doses, IGF-1 stayed above baseline for up to 28 days, and no serious adverse reactions were reported (PMID: 16352683).

Do the pulses survive?

The obvious worry with a long-acting signal is that it might flatten the natural rhythm of growth hormone into a constant level. A follow-up study tested that directly by sampling blood every 20 minutes overnight in healthy young men, before and one week after a single injection. The number and size of growth hormone pulses did not change. What did change was the baseline between pulses, which rose 7.5-fold, pushing mean growth hormone up by 46% and IGF-1 up by 45% (PMID: 17018654).

That is the key finding about CJC-1295. It does not simply replace the body’s rhythm. It raises the floor underneath it. CJC-1295 did not go on to become an approved medicine, so its human record is limited to these early studies. Our CJC-1295 (With DAC) research guide covers it in more detail.

Why Researchers Watch IGF-1 So Closely

Almost every study of these two compounds reports IGF-1, and it is worth understanding why. Growth hormone itself is hard to measure meaningfully: it rises and falls in pulses, so a single blood sample can catch a peak or a trough by chance. IGF-1 is different. It is produced mainly by the liver in response to growth hormone and stays relatively stable in the blood across the day. That makes it a convenient summary of how much growth hormone activity there has been over recent days.

It also explains one of the most interesting contrasts between the two compounds. Tesamorelin raised IGF-1 by 81% over 26 weeks of daily use in the HIV trial. CJC-1295 with DAC raised IGF-1 1.5- to three-fold after a single injection, with the rise lasting more than a week. Both reach the same marker, but on very different timescales, and that difference in time course is what makes each one useful for different study designs.

Tesamorelin vs CJC-1295: Side by Side

Starting point

Tesamorelin uses the full 44-amino-acid hormone. CJC-1295 uses a modified version of the 29-amino-acid active fragment.

How each one lasts longer

Tesamorelin blocks the enzyme that switches GHRH off. CJC-1295 with DAC binds to albumin so it circulates for days. The first gives a modest extension. The second gives a very large one.

Half-life

Tesamorelin lasts well under an hour. CJC-1295 with DAC has a measured half-life of roughly six to eight days in people.

Effect on growth hormone

Tesamorelin produces stronger, more reliable growth hormone pulses with each dose, which raises IGF-1 over time. CJC-1295 with DAC keeps pulses intact but lifts the baseline between them for days after a single dose.

Human evidence

Tesamorelin has large randomised trials and regulatory approval behind it, plus studies on liver fat and cognition. CJC-1295 has a small number of early studies in healthy adults and was not developed into a medicine.

Research focus

Tesamorelin research centres on visceral fat, liver fat and brain ageing. CJC-1295 research centres on how sustained GHRH stimulation affects growth hormone patterns and IGF-1.

Which One Fits a Research Question?

When Tesamorelin fits

Tesamorelin is the obvious choice when a study needs a GHRH analogue that behaves like the natural hormone and has a large clinical literature to compare against. Questions about visceral fat, fat in the liver and the metabolic effects of restoring growth hormone pulses all have well-documented human reference points for Tesamorelin.

When CJC-1295 fits

CJC-1295 with DAC fits when the question is about duration: what happens when the GHRH receptor is stimulated continuously for days, how the pituitary keeps its rhythm under that pressure, and how IGF-1 responds to a sustained rather than pulsed signal. Its very long half-life is the whole point.

And the short-acting version

CJC-1295 without DAC sits in between. It has the stabilising amino acid swaps but no albumin linker, so it acts for a short time like a tougher Sermorelin. It is most often studied paired with a ghrelin-receptor peptide, which is why we supply it as the CJC-1295 (No DAC) + Ipamorelin (Blend). The differences between the two CJC versions are explained in CJC-1295 with DAC vs without DAC.

The Technical Breakdown: Two Ways to Beat DPP-4

This section is for readers who want the chemistry.

Why the front end matters

DPP-4 cuts peptides after the second amino acid when that residue is alanine or proline. GHRH starts Tyr-Ala, a textbook target. Removing those two residues produces GHRH(3-44), which binds the receptor poorly, so cleavage effectively inactivates the hormone.

Tesamorelin’s cap

The trans-3-hexenoyl group on Tesamorelin’s N-terminal tyrosine changes the shape and charge of the front end enough that DPP-4 no longer recognises it. The rest of the 44-residue sequence, including the C-terminal region that helps with receptor binding and stability, is unchanged. Tesamorelin is still cleared by other routes, which is why its half-life is extended rather than transformed.

CJC-1295’s substitutions

CJC-1295 starts from GHRH(1-29) and replaces four residues: D-alanine at position 2 (which blocks DPP-4), glutamine at position 8 and alanine at position 15 (which reduce other cleavage and improve stability), and leucine at position 27 (which removes an oxidation-prone methionine). These four changes make the fragment much tougher than Sermorelin.

The DAC linker

In the DAC version, a lysine at the end of the chain carries a maleimide-based reactive group. After injection it forms a covalent bond with a free cysteine on albumin, called cysteine-34. The peptide then shares albumin’s long life in circulation. The peptide part remains able to reach and activate the GHRH receptor while attached.

Why the pulses survive

Even under continuous GHRH stimulation, somatostatin still rises and falls on its own schedule, and the pituitary still has its own refractory periods. That is why the 2006 pulse study found normal pulse frequency with a raised baseline. The rhythm comes from more than GHRH alone.

Why Quality Control Matters for Both

Tesamorelin is a long peptide of 44 amino acids, so deletion sequences, where one residue failed to couple during synthesis, are a real risk and can be hard to separate from the full-length product. Its N-terminal cap must also be present and correct, because a missing cap gives a molecule that behaves like ordinary GHRH. CJC-1295 with DAC has its own challenge: the reactive linker must be intact for albumin binding to work, and it can degrade if handled badly.

How Crown Peptides verifies every batch

Every batch of Tesamorelin Research Peptide and CJC-1295 (With DAC) Research Peptide is tested by HPLC for purity and mass spectrometry for identity, which confirms the full chain and its modifications are present. Certificates are published on our Lab Reports page. Our guide on how to read a peptide certificate of analysis explains each section, and storage information covers handling the lyophilised powder.

Handling in the lab

CJC-1295 (With DAC) needs particular care, because its albumin-binding group is chemically reactive by design. That reactivity is what lets it latch onto albumin in the bloodstream, and it is also why identity testing by mass spectrometry matters: it confirms the linker is present and intact. Tesamorelin, as a 44-amino-acid chain, simply has more places where things can go wrong, which is why purity by HPLC is so important for it. Lyophilised powders are at their most stable when kept cold, dry and away from light, so they should go into the fridge or freezer as soon as they arrive. Once a vial has been reconstituted, it should be kept refrigerated, drawn from with clean technique and used within the window set out in our peptide reconstitution guide. Repeated freezing and thawing of a solution is best avoided, because each cycle gives the chain another chance to break down or clump. Small habits like these protect the purity that the certificate describes, all the way from the vial to the experiment.

Related Compounds Across the GHRH Family

Sermorelin

Sermorelin is the unmodified 29-amino-acid fragment that CJC-1295 was built from, and the natural baseline for both comparisons. See Sermorelin vs Tesamorelin and CJC-1295 vs Sermorelin.

The ghrelin-receptor side

Ipamorelin, GHRP-2 and GHRP-6 release growth hormone through a different receptor. Our Tesamorelin vs Ipamorelin article explains how the two pathways differ.

Downstream

IGF-1 LR3 lets researchers study the step after growth hormone directly, which is useful for separating the effects of GHRH stimulation from the effects of IGF-1 itself.

Tesamorelin and CJC-1295 Questions, Answered

Do Tesamorelin and CJC-1295 act on the same receptor?

Yes. Both are GHRH analogues and both activate the GHRH receptor on pituitary somatotrophs. The differences are in how long they last and how they are built, not in where they act.

Which one lasts longer?

CJC-1295 with DAC, by a wide margin. Its measured half-life in people is roughly six to eight days, against well under an hour for Tesamorelin.

Does a long-acting GHRH analogue flatten growth hormone pulses?

Not according to the 2006 study of CJC-1295. Pulse number and size were unchanged one week after injection. The level between pulses rose instead.

Why is Tesamorelin an approved medicine and CJC-1295 not?

Tesamorelin went through large randomised trials for a specific condition, HIV-associated abdominal fat, and was approved for that use. CJC-1295 was studied in early trials but was not taken through to approval, so its human data is much more limited.

Is CJC-1295 without DAC the same as Sermorelin?

Not quite. Both are based on the first 29 amino acids of GHRH, but CJC-1295 without DAC has four amino acid substitutions that make it more resistant to enzymes. It is a toughened version of the same fragment.

How is visceral fat measured in these studies?

The Tesamorelin trials measured it by CT scan, taking a single cross-sectional image at the level of the lower lumbar spine and calculating the area of deep abdominal fat on that slice. Because the same slice is measured before and after treatment, the change can be stated precisely, which is how the trials reported figures such as a 15.2% fall in visceral fat.

Is either controlled in the UK?

Neither is listed under the Misuse of Drugs Act, and both can be bought for laboratory research. See are peptides legal in the UK for the wider picture.

Where This Research Is Heading

The GHRH field is in an interesting place. Tesamorelin has shown that stimulating the body’s own growth hormone pulses can produce measurable changes in visceral fat and liver fat in people, and the liver work suggests effects that reach down to gene activity and fibrosis. That has pushed research interest towards fatty liver disease more broadly and towards the brain, where growth hormone and IGF-1 levels fall with age.

CJC-1295’s long-acting design raises a different set of questions that are still wide open. What happens to the pituitary over months of continuous GHRH stimulation? Does the raised baseline it produces affect tissues differently from bigger individual pulses? How does albumin-bound delivery change which tissues the signal reaches? Those are exactly the kinds of questions that need a long-acting compound to answer, and they are why CJC-1295 remains a staple of growth hormone research even though it never became a medicine.

Put side by side, the two molecules also make a natural experimental pair. A study that compares a short, natural-looking pulse from Tesamorelin with a sustained lift from CJC-1295 can start to separate the effects of growth hormone timing from the effects of growth hormone amount, one of the most important unresolved questions in the field.

Same Receptor, Different Clocks

Tesamorelin and CJC-1295 start from the same hormone and act on the same receptor. What separates them is time. Tesamorelin keeps the natural hormone almost intact and gives it just enough protection to work reliably, producing stronger pulses with each dose. CJC-1295 with DAC rebuilds a shorter fragment for toughness and ties it to albumin, so a single dose raises the growth hormone baseline for days while the natural rhythm carries on above it.

That makes them complementary rather than competing tools. One brings a deep clinical record on fat and metabolism. The other is the reference compound for sustained GHRH stimulation. Both Tesamorelin Research Peptide and CJC-1295 (With DAC) Research Peptide are available from Crown Peptides with batch-specific certificates, dispatched from the UK.