Are Peptides Steroids? How They Differ in Chemistry, US Law and Sport

No, peptides are not steroids. Peptides are strings of amino acids, the units proteins are made from. An anabolic steroid is a much smaller molecule related to testosterone, and US law makes it a Schedule III controlled substance.^[1][2] The confusion comes from the gym, where some peptides are sold for the same goal as steroids: more muscle, less fat. Peptides that raise growth hormone are banned in sport alongside steroids, under a different section of the anti-doping list, and none of them is approved for building muscle.^[10]

Peptides vs steroids at a glance

The chemistry: two different kinds of molecule

Testosterone is a C19 steroid, a compact molecule with 19 carbon atoms and a molecular weight of about 288.^[3] Federal law defines an anabolic steroid as any drug or hormonal substance chemically and pharmacologically related to testosterone, excluding estrogens, progestins, corticosteroids and DHEA.^[1]

A peptide is built differently, as a string of amino acids linked end to end. BPC-157 is 15 of them, Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val, with a molecular weight of about 1,420.^[5] Tesamorelin, the approved peptide that raises growth hormone, is 44 amino acids long.^[6] FDA treats any amino acid chain longer than 40 as a protein, so tesamorelin falls on the protein side of that line.^[4] Peptides are hard to absorb by mouth; HHS calls adequate oral absorption of peptides “inherently difficult and complex.”^[5] The approved exceptions are covered in peptides without needles.

Corticosteroids are also steroids, but they are a different drug class and are excluded from the legal definition of anabolic steroids.^[1] When people ask whether peptides are steroids, they almost always mean the anabolic kind.

How each is supposed to build muscle

Anabolic steroids work through the testosterone system. The peptides sold for muscle mostly work one step removed, by making the pituitary gland release more growth hormone. Some copy the hormone that triggers that release (GHRH analogs such as sermorelin, CJC-1295 and tesamorelin); others copy ghrelin, the hunger hormone that also triggers it (ipamorelin and the GHRP family).^[10] Growth hormone then raises IGF-1,^[8] and some products sold online are IGF-1 variants themselves.

The best-known product in this group is not a peptide. Ibutamoren, sold as MK-677, is a non-peptide molecule of about 529 daltons, taken by mouth, that acts on the ghrelin receptor.^[7][8][16] In a two-year trial in 65 healthy older adults, it raised fat-free mass by about 1.1 kg compared with a fall of 0.5 kg on placebo, but the extra mass did not make people stronger or improve their function. Fasting blood sugar rose and insulin sensitivity fell.^[8] FDA lists ibutamoren as a compounding safety risk because of a possible link to congestive heart failure.^[11] Our comparison of MK-677 vs HGH goes into that record.

Even growth hormone itself does little for strength in healthy young adults. A systematic review of 27 study groups found it added about 2.1 kg of lean body mass, but strength and exercise capacity did not seem to improve, and side effects such as fluid retention were more common.^[15]

US law: controlled substance vs unapproved drug

Anabolic steroids are listed in Schedule III of the Controlled Substances Act, including testosterone and dozens of related compounds, along with their salts, esters and ethers.^[2]

Peptides are not controlled substances. They are regulated as drugs, so selling one for human use without FDA approval, outside a lawful compounding pharmacy, is a drug-law violation rather than a narcotics offense. Human growth hormone is a special case: federal law makes it a crime, punishable by up to five years in prison, to distribute it for any use other than an authorized treatment of a disease ordered by a physician.^[9] That rule names growth hormone itself; it does not name the peptides that cause the body to release more of it. The status of each peptide is set out in are peptides legal.

Since October 28, 2026, HHS has said it does not intend to take enforcement action against 503A pharmacies that compound six peptides, including BPC-157 and TB-500, under strict conditions.^[5] None of the growth hormone peptides sold for muscle (CJC-1295, ipamorelin, GHRP-2, GHRP-6) or IGF-1 variants is on that list. The policy also states that compounded drugs are not FDA-approved.^[5]

In sport, both are banned

The World Anti-Doping Agency bans anabolic steroids under section S1, anabolic agents, at all times. S1 also covers SARMs such as ostarine, LGD-4033 and RAD140, which are neither steroids nor peptides.^[10] The growth hormone peptides fall under S2, peptide hormones and growth factors: GHRH analogs including CJC-1295, sermorelin and tesamorelin, secretagogues including ibutamoren and ipamorelin, GHRP-2 and GHRP-6, IGF-1 and its analogs, mechano growth factors, and TB-500.^[10] BPC-157 is named under S0, substances with no current approval for human use.^[10] All three classes apply in and out of competition.

Where the line blurs in practice

The products often come from the same places. In one FDA warning letter, a single website was selling SARMs, MK-677, the prohormones “19-Nor Andro” and “4-Andro”, and BPC-157 and TB-500 as injections and nasal sprays, all under a “research purpose only” label.^[12] FDA warned that SARMs may raise the risk of heart attack and stroke.^[12]

The people often overlap too. In a survey at four San Francisco gyms, steroid users reported using an average of 8.7 performance drugs, against 3.7 among non-users, and were more likely to misuse prescription drugs including growth hormone.^[14] An Endocrine Society statement found that most users of performance-enhancing drugs are not competitive athletes but recreational weightlifters, that many combine several drugs at high doses, and that use is linked to cardiovascular, psychiatric, hormonal, liver and kidney disorders and a higher risk of death.^[13] Swapping steroids for peptides does not move a user into a better-studied category: for CJC-1295, FDA describes the available clinical data as limited, and for ipamorelin it has no safety data for most injection routes.^[11] The broader safety picture is in are peptides safe.