Peptides for muscle growth: what the evidence shows

No peptide is FDA-approved to build muscle. The peptides marketed for muscle growth mostly act on the growth hormone system, such as CJC-1295, ipamorelin and sermorelin. Some of them raise growth hormone levels in people, but no controlled trial has shown that they make healthy adults stronger, and most are banned in sport at all times.

Which peptides are marketed for muscle growth?

Most belong to one family: substances that push the body to release more growth hormone, or that act like growth hormone or its partner hormone, IGF-1. A 2026 review groups the ones people commonly inject (Dominikowski et al., 2026):

• Growth hormone-releasing hormone (GHRH) analogs: sermorelin, tesamorelin and CJC-1295, with or without “DAC”.
• Growth hormone secretagogues: ipamorelin, GHRP-2, GHRP-6 and hexarelin, which act on the ghrelin receptor.
• Growth hormone and IGF-1 look-alikes: fragments such as AOD-9604, and lab-made versions such as IGF-1 LR3 and PEG-MGF.

Only one of these, tesamorelin, is an FDA-approved medicine, and only for reducing abdominal fat in adults with HIV and lipodystrophy (Egrifta WR label).

What does the evidence show?

They can raise hormone levels. In healthy adults, a single injection of CJC-1295 with DAC raised growth hormone 2- to 10-fold for 6 days or more, and IGF-1 for 9 to 11 days (Teichman et al., 2006). That study measured hormones, not muscle or strength.

They have not been shown to build muscle. The 2026 review found that most GHRH analogs and secretagogues have early-phase human studies that “do not address performance- or body-composition endpoints” (Dominikowski et al., 2026). A 2026 sports medicine review reached a similar view across peptides used for injury and performance: benefits are seen mainly in animal models, rigorous human safety data are scarce, and placebo effects amplified by social media may explain some of what users report (Mendias and Awan, 2026).

Growth hormone itself didn’t make people stronger. In a systematic review of trials in fit young adults, growth hormone increased lean body mass, but strength and exercise capacity did not seem to improve, and side effects such as fluid retention and fatigue were more common (Liu et al., 2008). In healthy older adults, it produced small changes in body composition and more side effects (Liu et al., 2007).

Tesamorelin works for its approved use. In a 26-week trial in people with HIV, visceral (deep belly) fat fell by 15.2% on tesamorelin and rose by 5.0% on placebo (Falutz et al., 2007). That result does not tell us anything about muscle in healthy people, and the label calls its effect on weight “neutral”.

Where do these peptides stand legally?

Sermorelin was once sold in the US as an approved medicine (Geref), but no approved sermorelin product is marketed today. CJC-1295 and ipamorelin were never approved, and the FDA has listed both among substances that may present significant safety risks in compounding (FDA).

US regulatory status

• CJC-1295 / ipamorelinUS status: Not approved

  Neither peptide is approved by the FDA for any use, and no FDA-approved product contains either one, alone or blended. The FDA has cited serious adverse events with CJC-1295, including increased heart rate and a systemic vasodilatory reaction; the nomination to allow it in compounding was withdrawn, and it is on no list that permits compounding. Ipamorelin is in category 2 (significant safety risks) for outsourcing facilities (503B), and its 503A nomination was withdrawn. WADA prohibits both at all times.

  As of October 16, 2026

  Sources891213

• SermorelinUS status: Discontinued

  No FDA-approved sermorelin product is marketed in the US. Geref (EMD Serono) was discontinued in 2008 and its approvals were withdrawn effective June 18, 2009; in 2013 the FDA determined it was not withdrawn for safety or effectiveness reasons. Sermorelin acetate is under evaluation (category 1) for outsourcing-facility compounding, which is not FDA approval, and WADA prohibits it at all times.

  As of October 16, 2026

  Sources9131415

• TesamorelinUS status: Approved for one use

  FDA-approved as Egrifta WR and Egrifta SV (Theratechnologies) only to reduce excess abdominal fat in adults with HIV and lipodystrophy; the labels say it is not indicated for weight loss. The first Egrifta approval was on November 10, 2010. Tesamorelin sold online as a “research” peptide is an unapproved drug, and the FDA has sent warning letters to sellers. WADA prohibits it at all times.

  As of October 16, 2026

  Sources29111617

Are muscle peptides banned in sport?

Yes, nearly all of them. The World Anti-Doping Agency’s 2026 Prohibited List bans, at all times, in and out of competition (WADA):

• GHRH and its analogs, naming CJC-1295, sermorelin and tesamorelin.
• Growth hormone secretagogues and releasing peptides, naming ipamorelin, GHRP-2 and GHRP-6, among others.
• Growth hormone fragments, naming AOD-9604.
• Growth factors, including IGF-1 and its analogs, mechano growth factors, and thymosin beta-4 derivatives such as TB-500.
• Non-approved substances, naming BPC-157.

The List also covers “other substances with similar chemical structure or similar biological effect(s)”, so a peptide not named on it is not automatically allowed. If you compete in a tested sport, check with your anti-doping organization before taking anything.

Side effects and safety

For CJC-1295, the FDA has identified serious adverse events including a faster heart rate and a body-wide reaction in which blood vessels widen. For ipamorelin, it cites a published study in which serious adverse events, including death, occurred when it was given intravenously (FDA). The FDA also warns that injected peptides may cause immune reactions because of aggregation and impurities.

Reported effects across growth hormone-axis peptides include fluid retention, muscle and joint symptoms and blood-sugar changes, along with a plausible but unproven concern about promoting tumor growth (Dominikowski et al., 2026). In trials of growth hormone itself in older adults, swelling, joint pain, carpal tunnel syndrome and breast tissue growth in men were more common (Liu et al., 2007). Products sold online add the risk of wrong contents, wrong strength and contamination.

Questions people ask