Mislabeling, Incorrect Strength and Degradation Products
What testing of peptide products bought online and regulator reviews show about wrong amounts, impurities, endotoxin and unverified identity, and why a label cannot be trusted.
Content last updated . This page has not been medically reviewed.
If you feel unwell after injecting a product
In the US, call 911 for an emergency. For a possible wrong amount or overdose, US Poison Help is 1-800-222-1222 (other countries: Poison Help by Country). Signs of low blood sugar that WHO lists for wrongly dosed semaglutide products include blurred vision, palpitations, dizziness, sweating, seizure and loss of consciousness. [1] FDA describes a report of redness, swelling, pain and a red lump at the injection site after a product labeled as compounded tirzepatide. [2] See When to Seek Urgent Help for more.What "mislabeled" can mean
A peptide product can fail in several different ways, and they are not the same problem. The label can name the wrong substance. The right substance can be present in a different amount than printed. The sample can contain other peptide-related impurities, leftover chemicals or metals. Or it can be contaminated with bacteria or endotoxin (fragments of bacteria that can cause fever and inflammation). Testing studies have found each of these in products sold outside regulated pharmacy channels. This page is information only and does not describe how to check a product at home, because no home check can establish that an injectable is safe.What testing studies found
| Study (product class) | What was tested | Findings |
|---|---|---|
| 2024 online-purchase study (semaglutide sold without a prescription) | Three vials delivered from six illegal online pharmacies | Vials judged probable substandard or falsified; semaglutide content exceeded the labeled amount by 28.56% to 38.69%; endotoxin found in all samples; measured purity 7.7% to 14.37% against a 99% label claim; no viable microorganisms at time of testing [3] |
| 2018 Belgian study (ten commonly falsified peptide drugs, three suspected illegal internet pharmacies) | Active ingredient, impurities, elements, solvents | Wide variation in amount per unit; purity 5% to 75% for cysteine-containing peptides; arsenic and lead found, some up to ten times the ICH limit for injected drugs [4] |
Both studies are small and test purchases, so they show what can happen, not how often it happens across all products. In the 2024 study the number of vials was three. The Belgian study covered falsified versions of drugs, not every peptide product. [3][4]
"Research use only" labels
FDA has told sellers that "Research Use Only" and "not for human consumption" wording does not change what a product is when the seller's website shows it is intended for people. [6] A research label does not mean a product was made or tested to a standard for human injection.Degradation
Peptides can break down or change over time, which is one reason the amount present can differ from the label. The science is covered in Stability and Storage: Why Peptides Degrade. A lab report on one batch on one day does not show what is in a vial later; see Online Certificates of Analysis for Peptides.Bottom line
Identity, strength, purity and sterility are four separate questions, and an unregulated label answers none of them reliably. Anyone using or considering a peptide medicine should talk with a licensed prescriber and a state-licensed pharmacist. Suspected problems can be reported (see Reporting Adverse Events). This is not legal or medical advice.Frequently asked questions
Can a peptide label be wrong about the amount?
Yes. In a 2024 study of semaglutide vials bought online without a prescription, the measured content was above the labeled amount in all three delivered samples. [3]
Is "99% pure" on a label reliable?
Not on its own. The same study measured purity of 7.7% to 14.37% in vials claiming 99%. [3]
Can a product have the right peptide and still be unsafe?
Yes. Endotoxin was found in all samples in that study even though no peptide-like impurities were identified. [3] Heavy metals were found in falsified peptide drugs in the Belgian study. [4]
Does "for research purposes" make a product safe or legal?
No. FDA has said such labels do not override evidence that a product is intended for human use. [6]
What does FDA say about compounded versions of GLP-1 drugs?
They are not FDA approved and not reviewed for safety, effectiveness or quality before marketing. [2]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: approved medicine, evidence of harm, insufficient evidence. A "99% pure" claim is a marketing claim unless an independent laboratory shows it.
What regulators say
FDA says some compounded semaglutide products are salt forms (semaglutide sodium or acetate) that are different active ingredients from those in the approved drugs, and it knows of no lawful basis for their use in compounding. [2] That is an example of an identity problem: a name on a label can describe a different chemical form than the approved medicine.
FDA's published list of bulk substances with possible significant safety risks gives reasons that apply to several promoted peptides: risk of immunogenicity (the immune system reacting to the product), aggregation (peptide molecules clumping), and peptide-related impurities. [5] The list says, for example, that for BPC-157 FDA found no, or only limited, safety information for the proposed routes, so it cannot say whether the drug would cause harm. Several of these substances are shown as nominations that were later withdrawn, so read the page itself for each one. [5]
References
- World Health Organization, Questions and answers on semaglutide injection products. Read 2026-10-22.
- U.S. Food and Drug Administration, FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (content current as of 10/01/2026). Read 2026-10-22.
- Multifactor quality and safety analysis of semaglutide products sold by online sellers without a prescription, J Med Internet Res 2024. Read 2026-10-22 (abstract).
- Impurity profiling of the most frequently encountered falsified polypeptide drugs on the Belgian market, Talanta 2018. Read 2026-10-22 (abstract).
- U.S. Food and Drug Administration, Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 04/22/2026). Read 2026-10-22.
- U.S. Food and Drug Administration, Warning Letter to Gram Peptides (721806), 03/31/2026. Read 2026-10-22.