Peptides vs. Anabolic Steroids: Long-Term Risks Compared

Two very different bodies of evidence

Anabolic-androgenic steroids (AAS) and growth hormone peptides get compared constantly in lifting circles. The long-term question is hard to answer, because the evidence for the two classes looks nothing alike.

The harms of AAS come from people who actually used them: Danish registry cohorts followed for about 11 years and US imaging studies of long-term users. The peptide side has short clinical trials, mostly in patients or older adults, at doses that don't match what lifters describe. As of October 2026, no study has followed healthy lifters on growth hormone peptides for years, and no trial has compared peptides with AAS head-to-head.

So fewer documented harms doesn't mean safer over the long term. For peptides, much of the long-term record hasn't been written yet. Our overview of long-term effects of peptide use in bodybuilding covers the wider picture.

How each class works

AAS are testosterone and its synthetic relatives. They bind the androgen receptor in muscle and nearly every other tissue, which is why their side effects reach so many organs.

The peptides most used in bodybuilding work upstream, prompting the pituitary to release more growth hormone (GH), which raises IGF-1. They fall into two groups:

• GHRH analogues, such as CJC-1295, tesamorelin and sermorelin, mimic growth hormone-releasing hormone and act at the GHRH receptor.
• Ghrelin receptor agonists, such as ipamorelin, mimic ghrelin and act at the GH secretagogue receptor. MK-677 (ibutamoren) works the same way. It's an oral small molecule rather than a peptide, but it's sold and discussed alongside them.

Users often combine one from each group, most commonly Mod GRF 1-29 (CJC-1295 without DAC) with ipamorelin. As of October 2026, we found no controlled human trial of that combination.

Testosterone suppression and the GH axis

Shutting down natural testosterone production is the best-documented long-term cost of AAS. In a 2015 study, 19 untreated former long-term users had smaller testicles and lower testosterone than 36 weightlifters who had never used AAS. Five of them still had testosterone below 200 ng/dL between 3 and 26 months after stopping. Of 24 former users in total, 7 had a major depressive episode during withdrawal.

Growth hormone secretagogues don't act on the androgen receptor, so the same suppression isn't expected. That's an argument from mechanism, not a measurement: we found no long-term study of testicular function in lifters using these peptides. Many lifters also run them alongside AAS, which hides any separate effect.

What these compounds do change is the GH axis itself. In 2006 studies of CJC-1295 in healthy adults, a single injection raised mean GH 2- to 10-fold for 6 days or more and IGF-1 1.5- to 3-fold for 9 to 11 days. In tesamorelin's Phase 3 trials, 47% of patients had IGF-1 more than 2 standard deviations above normal after 26 weeks, and the prescribing label advises monitoring. The label also asks prescribers to weigh the risk carefully in anyone with a history of cancer.

Heart and blood vessels

The cardiovascular record is the strongest part of the case against AAS.

• A 2017 Circulation study compared 86 male weightlifters aged 34 to 54 who had used AAS for at least 2 years with 54 nonusers. Users had lower left ventricular ejection fraction (52% vs 63%) and more coronary plaque, and plaque volume rose with cumulative years of use.
• A 2025 Danish registry study followed 1,189 men sanctioned for AAS use and 59,450 matched controls for an average of 11 years. Adjusted for other factors, users had about 3 times the risk of heart attack and 3.6 times the risk of heart failure. Their risk of cardiomyopathy was almost 9 times higher.
• The Endocrine Society's 2014 scientific statement describes the usual AAS lipid pattern as lower HDL and higher LDL, most marked with oral 17-alpha-alkylated steroids.

The GH secretagogues haven't been through anything comparable. The human data they do have includes warning signs:

• MK-677: a Phase IIb trial gave 25 mg a day or placebo to 123 older adults recovering from hip fracture. It was stopped early because of a congestive heart failure signal in a small number of patients. Whether that applies to young, healthy lifters is disputed.
• CJC-1295: FDA's December 2024 advisory committee review describes a Phase 2 trial in HIV lipodystrophy that was terminated after a participant had a fatal heart attack 2 hours after his 11th weekly dose. The attending physician blamed undiagnosed coronary disease, and the trial was never published. The 2006 studies also reported raised heart rate and vasodilatory reactions.
• Tesamorelin: in pooled Phase 3 data from 806 HIV patients, triglycerides and the cholesterol-to-HDL ratio fell compared with placebo. That's a favorable lipid change in one patient group, not evidence that tesamorelin protects the heart.

As of October 2026, no cardiovascular outcome trial exists for any GH secretagogue.

Blood sugar, liver and lipids

Reduced glucose tolerance is the most consistent metabolic cost of raising GH, and it shows up across the trials.

• In a 2-year trial in 65 healthy adults aged 60 to 81, MK-677 at 25 mg a day raised fasting glucose by about 5 mg/dL and lowered insulin sensitivity. LDL fell slightly, while cortisol rose.
• Tesamorelin's label reports HbA1c of 6.5% or higher in 5% of patients versus 1% on placebo (hazard ratio 3.3), and it advises glucose checks during treatment.
• Ipamorelin's Phase 2 trial after abdominal surgery used 0.03 mg/kg IV twice daily for up to 7 days. The ipamorelin group had more hypokalemia, insomnia and hyperglycemia at discharge than the placebo group. Two people in that group died after treatment ended, and FDA said it was unclear whether ipamorelin played a part.

For AAS, the Endocrine Society statement links liver damage, including peliosis hepatis and liver tumors, almost entirely to oral 17-alpha-alkylated steroids. It adds that hard training raises liver enzymes by itself, so some reports may overstate liver harm.

Long-term liver and lipid effects of GH peptides in healthy lifters haven't been studied. A missing study isn't a clean result, so it would be wrong to say peptides carry no liver or lipid cost.

Mortality

Two Danish registry studies give the clearest long-term picture for AAS. A 2019 study of 545 men who tested positive at fitness centers found mortality about 3 times that of matched controls. A 2024 study of 1,189 sanctioned men, with a mean age of 27 at entry and about 11 years of follow-up, counted 33 deaths. That compared with 578 deaths among 59,450 controls, a hazard ratio of 2.81. Deaths from natural causes and from accidents, violence or suicide were both higher.

These are observational studies, and AAS users may differ from controls in ways registry data can't fully adjust for, such as other drug use. Still, the association holds across cohorts. There are no comparable data for GH peptides.

What each class actually delivers

AAS reliably add muscle, which is why people accept the risks above. The case for GH peptides as muscle builders is much weaker. In the 2-year MK-677 trial, fat-free mass rose by 1.1 kg while the placebo group lost 0.5 kg, but strength and function didn't change. Tesamorelin cut visceral adipose tissue by about 15% relative to placebo over 26 weeks in HIV patients, without changing body weight.

FDA's 2024 review found no articles on CJC-1295's effectiveness in people with GH deficiency, and ipamorelin's only efficacy trial missed its primary endpoint. As of October 2026, no trial has tested any of these compounds for muscle gain in healthy lifters, so projections of steady multi-year muscle gain from peptide cycles aren't based on data. Our article on peptide cycling strategies covers what's known about on/off schedules.

Legal status and sport

As of October 2026, CJC-1295 and ipamorelin aren't approved as drugs anywhere. FDA's compounding advisory committee voted against adding ipamorelin (October 2024) and CJC-1295 (December 2024) to the 503A bulks list. Tesamorelin is a prescription medicine, sold as Egrifta, approved only to reduce excess abdominal fat in HIV-associated lipodystrophy. Research-use vials sold online aren't the same product.

WADA's 2026 Prohibited List bans AAS under S1.1. It names CJC-1295, tesamorelin, ipamorelin and ibutamoren under S2.2.4, so both classes are banned at all times for tested athletes. Our guide to the legal risks of peptide use covers the rest.

Side-by-side summary

What we still don't know

• Whether years of raised GH and IGF-1 in healthy adults change cancer risk or glucose control.
• Whether GH secretagogues affect testicular function at the doses users report.
• How combining peptides with AAS, which many lifters do, changes the risk of either.