Approved, Investigational and Unapproved Peptides: What the Categories Mean

Why the category matters

"Peptide therapy" is used for very different things. Some peptides are medicines that a regulator has reviewed. Others are experimental compounds that exist only in research studies. Others are sold online or through clinics with no regulator review at all. The category tells you what kind of checking has happened before a product reaches a person. For background on the molecules themselves, see what peptides are.

Evidence labels used on this page: approved medicine (a regulator has approved it for a named use), preclinical (cells/animals only), insufficient evidence, and marketing claim.

Approved Medicines

In the United States, a drug developer files a New Drug Application to show that a drug is safe and effective for its intended use in the population studied, and FDA reviewers examine all of the submitted data before deciding. [1] Approval is specific to a use. Tesamorelin (a growth-hormone-releasing peptide) is an approved medicine for one indication: reducing excess abdominal fat in HIV-infected adults with lipodystrophy. Its label also says it is not indicated for weight loss management. [2] That approval does not extend to other uses people may advertise.

Approval can also end. Sermorelin was once FDA-approved to help diagnose and treat growth hormone deficiency in children, but the manufacturer discontinued it and FDA withdrew approval of the applications in 2009. FDA later determined it was not withdrawn for reasons of safety or effectiveness. [3] GLP-1 medicines have their own guide: see GLP-1 medicines.

Investigational Compounds

An investigational compound is a molecule being studied for possible use as a medicine. Once a sponsor wants to test a new molecule in people, it becomes a new drug under U.S. law, and the sponsor uses an Investigational New Drug (IND) application to get the exemption that allows studies to begin. [4] The application must include nonclinical safety data, manufacturing information and detailed study plans, and the sponsor must wait 30 days for FDA to review it before starting. [4]

Being in a study does not make a compound approved, and it does not mean the compound works. Preclinical work (cells and animals) mainly asks whether a drug could cause serious harm before people receive it. [5] It is not a substitute for studies in people. [6] Several peptides discussed online, such as thymosin beta-4 (see TB-500 and thymosin beta-4), have small human studies for specific uses, but not an approved product for the uses being marketed.

Unapproved Peptides

An unapproved peptide is a product that has no approval and is not in an authorized study. This group includes products labeled "research use only." FDA warning letters say that such labels do not decide the question: when a website's claims show a product is meant for human use, FDA treats it as a drug. [7] In an August 2026 warning letter to an online seller, FDA described several injectable peptides, including a tesamorelin product, as unapproved new drugs. [8] Selling a version of an approved molecule does not make that seller's product the approved one.

FDA states that unapproved drugs do not carry the same assurances of safety and effectiveness as drugs under FDA oversight, and may be contaminated, counterfeit, or contain varying amounts of active ingredient or different ingredients. [7] See peptide safety and adverse events.

Regulatory Status

Compounding. Compounded drugs are not FDA-approved, which means FDA does not verify their safety, effectiveness or quality before they are marketed. [9] Pharmacists and physicians working under section 503A may use only bulk substances that meet a USP or National Formulary standard, are components of FDA-approved drugs, or appear on FDA's bulks list. [10] FDA keeps a public page of bulk substances that may present significant safety risks. Its current version also lists substances whose nominations were withdrawn, among them BPC-157, CJC-1295, the TB-500 fragment, Semax and Selank, and describes the safety gaps it saw for each (page current as of April 22, 2026). [11]

Sport. The World Anti-Doping Agency's 2026 Prohibited List bans BPC-157 under its class of substances with no current approval for human therapeutic use, and lists thymosin-beta-4 derivatives such as TB-500, CJC-1295, sermorelin, tesamorelin and ipamorelin as prohibited at all times. [12]

Other countries. Rules differ by country and change. This guide states the status only for the United States (FDA) and for anti-doping rules (WADA); it does not state the status elsewhere. This is not legal advice.

How to use this page

Ask of any peptide product: Is it approved, and for what use? Is it in a registered study? Or is it neither? Then see how to evaluate peptide claims and talk with a licensed clinician before using any product (talking with a health professional).