What it is
Tesamorelin is a synthetic analogue of growth hormone releasing hormone (GHRH). A trans-3-hexenoic acid group is added to the human GHRH sequence to slow breakdown and extend its action. It works upstream: instead of supplying growth hormone directly, it prompts the pituitary to release the body’s own growth hormone in a more natural, pulsatile way, which in turn raises IGF-1.
It is the only GHRH analogue with full regulatory approval. It is marketed (as EGRIFTA and later formulations) for the reduction of excess visceral abdominal fat in people living with HIV who have lipodystrophy. Everything outside that indication is off-label or research territory.
What people use it for
The approved and best-supported use is shrinking visceral adipose tissue (VAT), the deep fat around the organs, as opposed to the subcutaneous fat you can pinch. People also explore it for general body composition, sleep and recovery, on the theory that a gentle rise in natural growth hormone helps. Those wider uses are far less well evidenced than the visceral fat data.
Typical dose range
The standard studied dose is 2 mg once daily, injected subcutaneously. A newer formulation delivers roughly 1.28 mg daily in a smaller injection volume with reportedly similar effect. Dosing is daily because the half-life is short and the pituitary response follows the dose. Higher doses do not have a strong evidence base and increase the chance of fluid-retention side effects and IGF-1 climbing too high.
Reconstitution and dose maths are easy to get wrong with a peptide like this. Work them out carefully: Peptide Calculator - Reconstitution & Dosage | Buy Peptides UK
Half-life and frequency
The plasma half-life is roughly 1 hour (often cited around 26 to 38 minutes for the parent peptide, with effective action a bit longer). Because clearance is fast, the protocol is once-daily dosing, commonly at night to sit with the body’s natural overnight growth hormone pulse. Skipping days undercuts the visceral fat effect, which in trials built up over weeks rather than appearing quickly.
Reconstitution (typical)
Supplied as a lyophilised (freeze-dried) powder. Typical practice is to let the vial reach room temperature, then add bacteriostatic water (sterile water with 0.9% benzyl alcohol) slowly down the inside wall of the vial rather than blasting the powder. Swirl gently to dissolve; do not shake hard, since aggressive agitation can damage the peptide. The exact volume of water you add sets your concentration, so decide your target concentration first and calculate backwards: Peptide Calculator - Reconstitution & Dosage | Buy Peptides UK
Storage
Keep the sealed lyophilised vial cold, ideally frozen at around -20 C for long-term storage, away from light. Once reconstituted, store at 2 to 8 C (a fridge), keep it out of light, and use it within roughly 28 days while the benzyl alcohol keeps bacterial growth down. Do not freeze a reconstituted vial; the freeze-thaw cycle degrades the peptide.
Common side effects
From the controlled trials, the most common reactions were:
- Injection-site reactions: redness, itching, pain, bruising
- Joint pain (arthralgia) and muscle pain (myalgia)
- Pain in the extremities
- Fluid retention: peripheral oedema, and in some cases carpal tunnel type symptoms
Two effects deserve specific attention because they are mechanism-driven, not just nuisance:
- Glucose intolerance. Raising growth hormone can worsen blood sugar control. In trials, more people on tesamorelin crossed into a diabetic HbA1c range than on placebo. Anyone with prediabetes, diabetes or strong family risk should treat this as a real consideration, not a footnote.
- IGF-1 elevation. A large share of trial participants pushed IGF-1 above 2 standard deviations, and a meaningful fraction above 3. The long-term consequences of sustained high IGF-1 are genuinely unknown, and elevated IGF-1 is the reason the label warns against use with active cancer.
Hypersensitivity reactions have occurred. Anyone with an active or recently treated malignancy, or who is pregnant, falls outside any reasonable-risk use.
Stacking and co-solubility
Tesamorelin is a GHRH-class secretagogue, so stacking it with a separate GHRH or with a GH-releasing peptide is doubling down on the same axis and amplifies the same risks (fluid retention, blood sugar, IGF-1) rather than adding a new benefit. There is no good human data supporting any particular stack. If two peptides are combined, that is usually done by drawing from two separately reconstituted vials rather than co-mixing powders, since each peptide has its own stability profile. Keep blood sugar and, ideally, IGF-1 monitored if going beyond the basics.
Evidence grade (human RCT / small human / animal-only / anecdote)
Human RCT for the core claim. The visceral fat effect rests on two pivotal randomised, double-blind, placebo-controlled trials over 26 weeks, with VAT reductions in the region of 15 to 20 percent versus placebo, and subcutaneous fat largely unchanged. That is unusually strong for this corner of the peptide world.
Everything beyond visceral fat (sleep, recovery, general body recomposition, longevity) drops to weak or anecdotal. The strong data is narrow; do not let it borrow credibility for the broader claims.
Honest unknowns
- The long-term effect of keeping IGF-1 elevated for months or years is not known.
- Almost all the robust safety and efficacy data comes from people with HIV-associated lipodystrophy. How cleanly that transfers to healthy adults using it for body composition is not established.
- Whether the visceral fat returns after stopping, and how fast, is not well characterised in the general-use setting.
- Most non-prescription supply is unregulated, so actual contents, dose accuracy and sterility vary. Purity you cannot verify is a risk in itself.
Research use only. Not medical advice. 18+.