Are peptides steroids?

No. A peptide is a chain of amino acids linked by peptide bonds; a steroid is a much smaller molecule built on a fused ring system of 17 carbon atoms. The two are separate chemical classes, and they are treated separately by United States drug law and by the WADA Prohibited List.

Two different kinds of molecule

The confusion is understandable. Both words turn up in conversations about hormones, muscle and doping, and both groups include natural hormones the body makes itself. Chemically, however, they are built in entirely different ways.

The National Library of Medicine's controlled vocabulary, MeSH, defines peptides as compounds "composed of amino acids joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures". Short chains of roughly 2 to 12 amino acids are called oligopeptides, chains of roughly 13 or more are called polypeptides, and proteins are larger versions of the same idea. The general background is on the page about what peptides are.

Steroids are defined by a shape rather than by building blocks. According to MeSH, they "have a common nucleus, a fused, reduced 17-carbon atom ring system", and the group includes cholesterol, numerous hormones, bile acids and certain vitamin precursors. A steroid is not a chain at all: it is a compact carbon frame with small groups attached to it.

The difference shows up clearly in size. Testosterone has the formula C19H28O2 and a molecular weight of 288.4. BPC-157, a short laboratory-made peptide, is a chain of 15 amino acids weighing 1,419.5 grams per mole. Semaglutide is 31 building blocks long, with a mass of 4,113.58 daltons; teriparatide is the first 34 amino acids of human parathyroid hormone; and somatropin, the medicine form of human growth hormone, is a single chain of 191 amino acids. Insulin, another peptide hormone, consists of two chains of 21 and 30 amino acids.

Side by side

Each row compares the two classes as the cited labels, registers and statutes describe them. It is a description of chemistry and status, not a comparison of usefulness.

The production row follows from the chemistry. According to their United States labels, teriparatide is made with a modified strain of the bacterium Escherichia coli; the semaglutide chain is produced with yeast; and somatropin comes from Escherichia coli or from a mouse cell line, depending on the manufacturer. The label for testosterone cypionate describes it as an oil-soluble ester of the hormone that is "insoluble in water".

What "steroid" means in everyday speech

In conversation, "steroids" usually means anabolic androgenic steroids. MeSH describes these as "synthetic, or human-made, variations of the male sex hormone testosterone". They are a subgroup of the steroid class, not the whole of it.

The same word also covers corticosteroids, which have a different function. Prednisone, for example, is described on its United States label as a glucocorticoid, and glucocorticoids as "adrenocortical steroids, both naturally occurring and synthetic". The legal definition of an anabolic steroid in the United States draws exactly this line: it covers substances "chemically and pharmacologically related to testosterone (other than estrogens, progestins, corticosteroids, and dehydroepiandrosterone)".

Peptides that act on the same hormone system

Some peptides influence the hormone system that steroids belong to, which adds to the confusion. The WADA 2026 list groups chorionic gonadotrophin, luteinizing hormone, gonadotrophin-releasing hormone and its analogues, and kisspeptin and its analogues together as "testosterone-stimulating peptides in males" under S2.2.1.

These molecules remain peptides. They act on the glands that produce hormones rather than being steroids themselves, and the list files them in the peptide section, not under anabolic agents. Acting on the same hormone system does not make one class a stand-in for the other, and this page describes no such use.

How United States law treats each class

For anabolic steroids, the key date is 29 November 1990. Title XIX of Public Law 101-647, the Anabolic Steroids Control Act of 1990, added anabolic steroids to Schedule III of the Controlled Substances Act and wrote the first statutory definition. That early definition covered testosterone-related substances "that promotes muscle growth".

The Anabolic Steroid Control Act of 2004, Public Law 108-358, signed on 22 October 2004, replaced that definition. The new wording no longer contains the muscle-growth condition, adds dehydroepiandrosterone to the exclusions, and names further substances such as androstanediol and androstenediol. Today the federal regulation for Schedule III lists anabolic steroids under paragraph (f), with the drug code 4000. The prescribing information for testosterone cypionate states that it "contains testosterone, a Schedule III controlled substance".

Peptides have no equivalent class-wide schedule. The Schedule III regulation contains no entry for human growth hormone. Instead, the same 1990 act took a different route for growth hormone: it amended the Federal Food, Drug, and Cosmetic Act so that knowingly distributing human growth hormone for any use other than an authorised medical one is punishable by up to 5 years in prison, or up to 10 years where a person under 18 is involved. The statute defines human growth hormone as "somatrem, somatropin, or an analogue of either of them".

Other peptides follow ordinary medicines law. Semaglutide, teriparatide and somatropin are approved and available only on prescription, while no approval of BPC-157 as a medicine could be found in any country examined in its monograph. How these rules play out beyond the United States is covered on are peptides legal and which peptides are FDA approved.

Where the WADA list puts each class

The WADA Prohibited List keeps the two classes in separate sections. Section S1, "Anabolic agents", is prohibited at all times, and all its substances are non-Specified. Its first part, S1.1, lists anabolic androgenic steroids such as testosterone, nandrolone and stanozolol, "and other substances with a similar chemical structure or similar biological effect(s) including their esters". Section S2 covers "Peptide hormones, growth factors, related substances, and mimetics", also prohibited at all times and also non-Specified.

Source: WADA Prohibited List 2026, sections S0 to S9; semaglutide and teriparatide from full-text searches recorded in their monographs.

Two details show that sport rules and drug law are separate systems. DHEA is excluded from the United States definition of an anabolic steroid, yet WADA prohibits it under S1.1. Growth hormone, which is not a controlled substance in Schedule III, is prohibited at all times under S2. The wider picture is on are peptides banned in sport.

What is documented about safety

For anabolic androgenic steroids, the United States label for testosterone cypionate lists serious adverse reactions reported in people who misuse them, including cardiac arrest, heart attack, heart failure, stroke, liver damage and serious psychiatric effects such as major depression, mania and aggression. In women it adds deepening of the voice and male-pattern baldness; in adolescents, early closure of the growth plates. The label notes that these reports are voluntary, so their frequency cannot be reliably estimated.

An Endocrine Society scientific statement from 2014 links performance-enhancing drug use to an increased risk of death and to cardiovascular, psychiatric, hormonal, liver and kidney disorders, and notes that most users are not competitive athletes but non-athlete weightlifters. A 2015 review adds that in men these steroids suppress sperm production and can cause testicular shrinkage and infertility, and that controlled trials of the high doses used outside medicine are lacking for ethical reasons. A meta-analysis of 187 studies estimated a global lifetime prevalence of use of 3.3 percent (95% confidence interval 2.8 to 3.8), with 6.4 percent in men and 1.6 percent in women.

Peptides have no shared safety profile, because they are not one kind of drug in the way anabolic steroids are. Each approved peptide medicine has its own label and its own warnings. For somatropin in healthy people, two independent systematic reviews found no gain in muscle strength, while swelling and fatigue became more common. For BPC-157, trials in people have been registered, but none has posted results in the trial register, so no human safety profile could be found in the sources reviewed for this page.

Common questions

Are peptides steroids?

No. A peptide is a chain of amino acids joined by peptide bonds, while a steroid is a compound built on a fused ring system of 17 carbon atoms. The two belong to different chemical classes, are treated differently in United States drug law, and sit in separate sections of the WADA Prohibited List.

What is the difference between a peptide and a steroid?

The building plan. A peptide is assembled from amino acids, the same building blocks as proteins, and ranges from a handful of units to more than a hundred. A steroid is a small, fat-soluble molecule with a four-ring carbon core; testosterone, for example, has the formula C19H28O2 and a molecular weight of 288.4. The peptide medicines described here are mostly injected under the skin, while prednisone, a steroid medicine, is taken as tablets.

Is testosterone a peptide?

No. Testosterone is a steroid hormone with the formula C19H28O2. In the United States it is a Schedule III controlled substance, and the WADA 2026 Prohibited List names it under S1.1, anabolic androgenic steroids.

Is growth hormone a steroid?

No. Human growth hormone, made as the medicine somatropin, is a protein hormone of 191 amino acids. It is not listed in Schedule III; United States law instead makes distributing it for anything other than an authorised medical use a separate federal offence. WADA lists it under S2.2.3, the peptide hormone section, not under S1.

Are peptides controlled substances like steroids?

Not as a class. United States law places anabolic steroids in Schedule III, but it has no equivalent schedule for peptides. Peptide medicines such as semaglutide, teriparatide and somatropin are prescription-only, growth hormone carries its own criminal provision, and no approval of a compound such as BPC-157 as a medicine could be found in the sources reviewed for this page.

Is prednisone an anabolic steroid?

No. Prednisone is a glucocorticoid, one of the corticosteroids, which are steroids with a different job in the body. The United States definition of an anabolic steroid expressly excludes corticosteroids, and the WADA list treats glucocorticoids separately under S9, prohibited in competition only and only by certain routes.

Are peptides banned in sport like steroids?

Many are, but under a different heading. The WADA 2026 Prohibited List puts anabolic androgenic steroids in S1 and peptide hormones, growth factors and related substances in S2, both prohibited at all times. Unapproved compounds such as BPC-157 fall under S0, while some peptide medicines, for example semaglutide and teriparatide, are not named on the list at all.

Is semaglutide a steroid?

No. Semaglutide is a peptide of 31 building blocks with a molecular mass of 4,113.58 daltons, a modified copy of the gut hormone GLP-1. It is a prescription-only medicine and does not appear on the WADA 2026 Prohibited List.

Sources

1. National Library of Medicine (2026). Medical Subject Headings, descriptor D010455, Peptides, scope note. NLM. https://id.nlm.nih.gov/mesh/D010455.html
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Drug schedules, prescription rules and anti-doping lists are revised over time, and each of them is a separate question from the chemistry described here. For an approved medicine the authoritative text is its current product label; for the legal status in a particular country, the relevant statute or regulator; and for anything to do with an individual's health or eligibility in sport, a physician or pharmacist and the athlete's anti-doping organisation.