Short answer: tesamorelin has far better evidence. Tesamorelin is an FDA-approved GHRH analog: in trials in adults with HIV and excess abdominal fat, it cut visceral (deep belly) fat by about 15% in 26 weeks without changing body weight. Ipamorelin is an unapproved ghrelin-receptor peptide; in people it has been studied in one pharmacokinetic study and a surgery trial that found no benefit over placebo, and it has never been tested for fat loss or muscle. Both raise growth hormone, through different receptors.
Tesamorelin vs ipamorelin at a glance
| Tesamorelin | Ipamorelin | |
|---|---|---|
| What it is | GH-releasing hormone (GHRH) analog | GH secretagogue (ghrelin receptor agonist pentapeptide) |
| Approval | Approved (US, 2010) | Not approved; furthest stage: Phase 2 |
| Human studies (counted in our records) | 15 | 2 |
| Half-life | ~8–11 min | ~2 h |
| Testosterone suppression score | 0/3 | Not established |
| Liver risk score | 0/3 | Not established |
| Evidence score | 3/3 | 1/3 |
| WADA | Prohibited at all times (S2.2.4 Growth hormone releasing factors) | Prohibited at all times (S2.2.4 Growth hormone releasing factors) |
| Receptor | GHRH receptor (like CJC-1295, sermorelin) | Ghrelin (GHS) receptor (like MK-677) |
| Body-composition evidence | Visceral fat −15.2% vs +5.0% placebo (26 weeks, HIV) | None in humans |
| SwissChems product | Tesamorelin, 2mg | Ipamorelin 2mg |
Scores run from 0 (none) to 3 (high); see our methodology. Data from the SARMs database.
Source: Sarmguide compound database; Tesamorelin: EGRIFTA WR (tesamorelin) prescribing information, DailyMed (updated 3 Aug 2026) (2026).
How they work
Tesamorelin copies growth hormone-releasing hormone, the brain signal that tells the pituitary to release GH; GH then raises IGF-1 (by 81% at 26 weeks in the main trial). Ipamorelin acts on the ghrelin receptor instead, producing a short GH pulse that peaked about 40 minutes after an IV dose in healthy men. In pigs, ipamorelin did not raise cortisol or prolactin, which is why it is called “selective”; this has not been confirmed in people. Because the two act on different receptors, they are sometimes combined, but that has not been studied.
What the trials show
| Outcome | Tesamorelin | Ipamorelin |
|---|---|---|
| Deep belly fat | −15.2% vs +5.0% placebo (412 adults with HIV, 26 weeks); came back after stopping | Not studied |
| Liver fat | Fell 4.1 points more than placebo over 12 months (adults with HIV and fatty liver) | Not studied |
| Lean mass | +1.2–1.3 kg vs no change on placebo (label) | Not studied in humans |
| Thinking skills | Better executive function in older adults (20 weeks) | Not studied |
| Other | No change in blood sugar control in type 2 diabetes (12 weeks) | No benefit for gut recovery after surgery (114 patients) |
Half-life
Tesamorelin’s half-life is very short, about 8–11 minutes after injection, although its effect on IGF-1 lasts; it is given once a day. Ipamorelin’s half-life is about 2 hours after IV infusion; no human half-life after injection under the skin has been published.
Side effects
| Tesamorelin (label data) | Ipamorelin |
|---|---|
| Injection-site reactions in 25% vs 14% on placebo | Adverse events as common as placebo in the surgery trial |
| Joint pain, swelling and carpal tunnel from fluid retention | FDA cites serious adverse events, including death, with IV use for gut motility |
| HbA1c of 6.5% or more in 5% vs 1% on placebo | Possible immune reactions from impurities (FDA) |
| IGF-1 above the normal range in 47% at 26 weeks; label says monitor IGF-1 | Black-market copies (Gly-ipamorelin) found |
| Not for use in pregnancy or active cancer | Safety of long-term subcutaneous use unknown |
Approval, legality and sport
Tesamorelin is FDA-approved (Egrifta, 2010; now Egrifta SV and WR) for adults with HIV-associated lipodystrophy, and is a prescription medicine. Ipamorelin has no approved product; the FDA lists it in Category 2 (significant safety risks) for outsourcing facilities. Both are prohibited at all times under WADA S2.2.4.
Verdict
For a measured, approved effect on deep belly fat, tesamorelin is the only GH peptide with that evidence, in people with HIV-associated fat gain; outside that group it has not been tested for fat loss. Ipamorelin reliably triggers a short GH pulse, but no trial shows a body-composition benefit, and the FDA lists it as a safety risk. For more options, see best growth hormone peptides, CJC-1295 vs ipamorelin and MK-677 vs ipamorelin.
Frequently asked questions
Is tesamorelin better than ipamorelin?
Yes, on evidenceEvidence: Trial
Tesamorelin is FDA-approved and cut deep belly fat by about 15% in 26-week trials in adults with HIV. Ipamorelin has no trial showing a body-composition benefit.
What is the difference between tesamorelin and ipamorelin?
Different receptorsEvidence: Human data
Tesamorelin acts on the GHRH receptor, like natural growth hormone-releasing hormone; ipamorelin acts on the ghrelin receptor, like MK-677. Both raise GH.
Does tesamorelin burn fat?
Deep belly fat, in HIVEvidence: Trial
It reduced visceral fat by 15.2% vs a 5.0% rise on placebo in adults with HIV and lipodystrophy, without changing weight, and the fat came back after stopping. It has not been tested for general fat loss.
Can you stack tesamorelin and ipamorelin?
Never studiedEvidence: Limited
They act on different receptors, so they are sometimes combined, but no study has tested the combination.
What are the side effects of tesamorelin?
Injection reactions, blood sugarEvidence: Trial
Injection-site reactions (25%), joint pain and swelling, HbA1c of 6.5% or more in 5% vs 1% on placebo, and IGF-1 above the normal range in 47% at 26 weeks.
What is the half-life of tesamorelin vs ipamorelin?
About 8–11 min vs 2 hoursEvidence: Human data
Tesamorelin about 8–11 minutes after injection; ipamorelin about 2 hours after IV infusion. No human half-life for ipamorelin under the skin has been published.
Are tesamorelin and ipamorelin banned in sport?
Yes, banned by WADAEvidence: Law
WADA names both under S2.2.4, prohibited at all times.
Sources
- Metabolic effects of a growth hormone-releasing factor in patients with HIV
- Long-term safety and effects of tesamorelin, a growth hormone-releasing factor analogue, in HIV patients with abdominal fat accumulation
- Effects of tesamorelin on non-alcoholic fatty liver disease in HIV: a randomised, double-blind, multicentre trial
- Effects of growth hormone-releasing hormone on cognitive function in adults with mild cognitive impairment and healthy older adults: results of a controlled trial
- Safety and metabolic effects of tesamorelin, a growth hormone-releasing factor analogue, in patients with type 2 diabetes: A randomized, placebo-controlled trial
- EGRIFTA WR (tesamorelin) prescribing information, DailyMed (updated 3 Aug 2026)
- EGRIFTA SV (tesamorelin) prescribing information, DailyMed (updated 31 Jul 2026)
- Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
- Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
- Ipamorelin, the first selective growth hormone secretagogue
- Analysis of new growth promoting black market products
- FDA: Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2 list; content current as of 22 Apr 2026)
- World Anti-Doping Code International Standard: Prohibited List 2026