Short answer: They raise growth hormone through different receptors. Tesamorelin copies GHRH and is FDA approved as Egrifta, only to reduce belly fat in adults with HIV lipodystrophy.1 Ipamorelin is a five-amino-acid ghrelin-receptor agonist that has never been approved; its human studies were given into a vein.23 FDA lists ipamorelin as a compounding safety risk.4 No trial compares them.
| Tesamorelin (Egrifta) | Ipamorelin | |
|---|---|---|
| What it is | The full 44-amino-acid GHRH sequence with an added fatty group1 | Pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2)2 |
| Receptor | GHRH receptor1 | Ghrelin (GH secretagogue) receptor2 |
| Approval status | FDA approved since 20101 | Never approved. FDA 503B Category 2 since September 29, 20234 |
| Approved use | Reducing excess abdominal fat in adults with HIV and lipodystrophy; not for weight loss1 | None |
| Label or study dose | Egrifta WR 1.28 mg or Egrifta SV 1.4 mg under the skin once daily; not interchangeable15 | 0.03 mg/kg into a vein twice daily for up to 7 days (ileus trial)6 |
| Half-life | 11 minutes (WR) and 8 minutes (SV) after one injection under the skin15 | about 2 hours after IV dosing3 |
| Main human results | Two 26-week trials: visceral fat −18% vs +2% on placebo, and −14% vs −2%1 | Ileus trial in 114 patients: time to first solid meal 25.3 vs 32.6 hours, not significant6 |
| Sport | WADA S2.2.4 (named)7 | WADA S2.2.4 (named)7 |
Tesamorelin acts on the GHRH receptor, the same one the brain's own growth hormone releasing hormone uses.1 Ipamorelin acts on the ghrelin receptor, like GHRP-6. In animal studies it released GH about as well as GHRP-6 but, unlike GHRP-6 and GHRP-2, did not raise ACTH or cortisol, which is why its developers called it selective.2 In healthy men given IV ipamorelin, GH peaked at about 40 minutes (0.67 hours) and then fell.3
Tesamorelin has two randomized label trials in adults with HIV and excess belly fat. After 26 weeks, visceral fat measured by CT fell 18% vs a 2% rise on placebo in one trial and 14% vs 2% in the other.1 The label warns about raised IGF-1, fluid retention and glucose intolerance, and says not to use it in pregnancy or with active cancer.1
Ipamorelin's largest human trial tested it after bowel surgery, given into a vein. It was well tolerated but did not speed recovery significantly.6 FDA notes that a published study reported serious adverse events including death when ipamorelin was given into a vein for gut motility, and that it has no safety information for other injection routes.4 No study has compared the two directly. These are study protocols, not personalized advice; confirm any dosing with your prescriber.
See the Egrifta WR dosing schedule, Egrifta WR side effects, Egrifta SV side effects, and the Tesamorelin and Ipamorelin guides.