Tesamorelin vs ipamorelin: tesamorelin is an FDA-approved analog of growth hormone-releasing hormone (Egrifta) with Phase 3 trial data, while ipamorelin is an unapproved five-amino-acid ghrelin-receptor agonist whose only published Phase 2 trial showed no efficacy. They reach growth hormone release through different receptors. Both are prohibited by WADA, and "research" tesamorelin sold online isn't the approved drug.
Research-use notice: This page summarizes published research and regulatory documents for general education. It isn't medical advice and contains no dosing guidance. Tesamorelin is a prescription drug; products sold as research chemicals under either name are unapproved and aren't regulated for quality. Last reviewed October 20, 2026.
Side by side
| Tesamorelin | Ipamorelin | |
|---|---|---|
| What it is | Synthetic GHRH analog, Theratechnologies (Egrifta) | Growth hormone secretagogue (ghrelin mimetic), discovered at Novo Nordisk |
| Receptor | GHRH receptor (pituitary) | Ghrelin receptor (GHS-R1a) |
| Size | 44 amino acids, with a trans-3-hexenoyl group | 5 amino acids |
| Human evidence | Phase 3 randomized trials | Phase 2 postoperative ileus trial; no efficacy over placebo |
| FDA status | Approved (2010); current form Egrifta WR | Never approved; Category 2 (503B) |
| WADA 2026 | Named, S2.2.4 (GHRH analogues) | Named, S2.2.4 (GH secretagogues) |
| Our price index | Tesamorelin prices | Ipamorelin prices |
How they work
- Tesamorelin is built on the full 44-amino-acid human GHRH, with a trans-3-hexenoyl group added to the first amino acid (tyrosine). That modification resists breakdown by the enzyme DPP-4. It binds the GHRH receptor on the pituitary and stimulates growth hormone (GH) release. Shorter GHRH analogs are compared in CJC-1295 vs sermorelin.
- Ipamorelin is a pentapeptide (Aib-His-D-2Nal-D-Phe-Lys-NH2) that activates the ghrelin receptor, GHS-R1a, the same target as GHRP-2 and GHRP-6. Novo Nordisk researchers described it as the first "selective" secretagogue because it didn't raise ACTH or cortisol in their experiments (Raun et al., Eur J Endocrinol 1998).
Different receptors, different sizes and very different evidence bases: that's the core of this comparison.
What the research found
Tesamorelin. The pivotal Phase 3 trial (Falutz et al., N Engl J Med 2007) enrolled 412 people with HIV and excess abdominal fat for 26 weeks (NATAP summary):
| Outcome at 26 weeks | Tesamorelin | Placebo |
|---|---|---|
| Visceral adipose tissue | -15.2% | +5.0% |
| IGF-I | +81% | -5% |
| Triglycerides | -50 mg/dL | +9 mg/dL |
| Stopped due to adverse events | 12.1% | 2.9% |
| Developed IgG antibodies | 48.6% | 2.7% |
The visceral-fat difference was significant (p<0.001), and there was no significant difference in glucose. These results apply to the population studied, people with HIV-associated lipodystrophy, and the prescribing information is the authoritative source on warnings.
Ipamorelin. In vitro, ipamorelin had an EC50 of 1.3 nmol/L and reached 85% of GHRP-6's maximum effect (Raun et al. 1998). Its only published human efficacy trial tested it intravenously for postoperative ileus (NCT00672074; 117 patients). Median time to the first tolerated meal was 25.3 hours vs 32.6 hours with placebo, which wasn't statistically significant (p=0.15). Adverse events occurred in 87.5% vs 94.8%, and development for that use wasn't pursued (Beck et al., Int J Colorectal Dis 2014).
Regulatory status
- Tesamorelin: FDA approved Egrifta on November 10, 2010 to reduce excess abdominal fat in HIV-infected patients with lipodystrophy. A single-vial formulation, Egrifta SV, was approved in November 2018 (GlobeNewswire), and Egrifta WR was approved on March 25, 2025 to replace it (Theratechnologies via SEC; Drugs.com). Tesamorelin isn't on FDA's significant-safety-risks page. FDA's August 24, 2026 warning letter to NuScience Peptides named tesamorelin among the products it sold (FDA).
- Ipamorelin: never approved. FDA's significant-safety-risks page (content current as of April 22, 2026) still lists ipamorelin acetate in Category 2 for 503B, added September 29, 2023, noting: "A study published in literature identified serious adverse events including death when ipamorelin was administered." It also appears in the "nominated but withdrawn" table for certain other injectable routes (FDA). It wasn't on the July 2026 PCAC agenda.
- FDA enforcement: FDA has rejected "research use only" disclaimers in a series of 2026 warning letters (Sheppard Mullin). See FDA peptide regulation in 2026 and are peptides legal?.
- WADA 2026: S2.2.4 names tesamorelin among GHRH analogues and ipamorelin among "growth hormone secretagogues (GHS) and their mimetics." Both are prohibited at all times (WADA).
What research buyers should check
- Identity by mass spec. Tesamorelin's mass must match the hexenoyl-modified 44-amino-acid peptide. Check the COA's mass spectrometry result against the published molecular weight, not just an HPLC purity figure.
- Substitution risk. Unmodified GHRH(1-44) or sermorelin passed off as "tesamorelin" is a plausible substitution. Both would show a different mass.
- Ipamorelin vs other secretagogues. A mass spec result should also rule out GHRP-2 or GHRP-6 sold under the ipamorelin name.
- Blends. Any blend needs a COA that identifies each component separately.
- Approved-drug copies. "Research" tesamorelin isn't Egrifta and isn't covered by its approval.
Our COA guide explains each test.
Prices and vendors
- Price history: tesamorelin price index and ipamorelin price index
- Vendor rankings with COA notes: best tesamorelin vendors and best ipamorelin vendors
- Compare per-milligram prices across vendors: peptide price comparison tool
Bottom line
Tesamorelin and ipamorelin both lead to growth hormone release, but the comparison is lopsided. Tesamorelin is a 44-amino-acid GHRH analog with Phase 3 data and FDA approval for one specific population. Ipamorelin is a small ghrelin-receptor agonist with animal selectivity data, one negative Phase 2 trial and an active Category 2 listing. Both are banned in sport, and research material under either name needs a mass spec identity check.
Sources are linked inline. We'll update this page as regulatory status changes.
