The Peptide Lab

It's a label for chemicals sold for laboratory research, not for use in people. It is not an FDA approval and not a quality grade; RUO products from different suppliers can differ a lot. FDA has said the label doesn't shield sellers whose websites imply human use, and in 2026 it sent warning letters calling RUO retatrutide and tirzepatide unapproved new drugs.^12,13,14 More in the four-ways cards in Basics.

RUO peptides are widely sold online. FDA's 2026 enforcement has focused on sellers that market them for human use, through warning letters.^12,13,14 The rules depend on the product and how it is marketed, and they are changing: an FDA "Interim Access Policy for Compounding Using Certain Peptides" has been under White House review since Oct 14, 2026 and is not yet in effect.¹⁸⁷ This app is not legal advice.

No. Quality varies widely between suppliers and even between batches. Independent testing is the way to tell them apart. In one published test purchase of online semaglutide, measured purity was far below the label and endotoxin was present, which shows why batch testing matters.^226,227 See card 3 in the four-ways cards in Basics.

Ask for a batch-specific certificate of analysis (COA) from an independent, third-party lab, and check that:

• The lot number on the COA matches the lot number on your vial
• The lab is named and can be looked up, and the report is dated
• Purity % is measured by HPLC
• Identity is confirmed by mass spectrometry
• Endotoxin and sterility results are included

The same generic COA shown for every batch, no lot number, an old or undated report, in-house testing only, a lab name you can't verify, or a seller that won't share a COA at all.

HPLC (high-performance liquid chromatography) separates what's in a sample, which is how purity % is estimated. Mass spectrometry (MS) measures the molecule's mass to confirm it is the peptide on the label. Researchers used LC-MS, the two combined, to test online semaglutide.²²⁶

Endotoxin is a toxin from bacteria that can cause fever and inflammation if injected. "Sterile" and "endotoxin-free" are different tests: in the online semaglutide study, the samples had no living microbes, yet every one contained endotoxin.²²⁶ That's why a complete COA reports both.

• Start with its card in Explore peptides: evidence badge, legal status and numbered sources.
• Search PubMed for published studies, and note whether they were in people or animals.
• Search ClinicalTrials.gov for registered human trials and their status.
• For approved products, read the official label on DailyMed or Drugs@FDA.
• Check every claim against its source in Sources.

• FDA-approved: a specific product approved for a specific use.
• Clinical trials: tested in people, not (yet) approved.
• Mostly animal data: little or no controlled human data.
• Anecdotal: mainly personal reports.

See the evidence badges in Basics.

Results in rats don't always carry over to people, and doses don't convert directly. Reviews of BPC-157, for example, note that most of its evidence comes from animal studies, with very limited human data.^15,16 A randomized, controlled human trial is the strongest kind of evidence.

BPC-157 is not FDA-approved. FDA removed it from its Category 2 compounding list on Apr 22, 2026 after the nomination was withdrawn, which did not add it to the list pharmacies may compound.^17,31 On July 23, 2026, FDA's advisory committee voted 8–6 to recommend adding it; the vote is advisory.¹⁸ As of Oct 9, 2026, FDA hadn't acted.¹⁹ It is also prohibited in sport by WADA.²¹ Details on the BPC-157 card.

• Semaglutide (Wegovy, Ozempic) acts on one hormone receptor, GLP-1. FDA-approved.¹
• Tirzepatide (Zepbound, Mounjaro) acts on two, GLP-1 and GIP. FDA-approved. In a head-to-head trial it led to more weight loss than semaglutide (20.2% vs 13.7% at 72 weeks).³
• Retatrutide acts on three: GLP-1, GIP and glucagon. It is still investigational; Lilly plans to file for approval in Q1 2027.^10,11

See the semaglutide, tirzepatide and retatrutide cards, or put them side by side in Compare.

An approved product was reviewed by FDA for safety, effectiveness and manufacturing quality. A compounded drug is custom-made by a pharmacy for a patient with a prescription and is not FDA-approved.⁸ With the GLP-1 shortages over, FDA has limited compounded copies of semaglutide and tirzepatide,^4,6 and it has warned about dosing errors with compounded semaglutide.⁹

1 mg (milligram) = 1,000 mcg (micrograms, also written µg). So 0.5 mg = 500 mcg, and 2.5 mg = 2,500 mcg. Mixing up the two is a 1,000-fold error, so always check which unit a number uses.

On a U-100 syringe, 100 units = 1 mL, so 1 unit = 0.01 mL. The math, step by step:

• Concentration = amount in the vial ÷ mL of water added
• mL needed = amount wanted ÷ concentration
• Units = mL × 100

Example: 20 mg in 2 mL = 10 mg/mL (10,000 mcg/mL); 500 mcg ÷ 10,000 mcg/mL = 0.05 mL = 5 units. This is arithmetic only, not a dose recommendation.

No. The total amount in the vial stays the same; more water only makes it more dilute. The same amount then takes more units to draw. For example, 500 mcg from a 20 mg vial is 5 units with 2 mL of water, 7.5 units with 3 mL, and 10 units with 4 mL.

Many are not. The World Anti-Doping Agency's Prohibited List covers many peptides, including BPC-157 and growth-hormone-releasing peptides. Athletes in tested sports should check the current list.²¹

Approval covers a specific product for a specific use; it doesn't cover every way people use that peptide. Many widely used products, like supplements, are never FDA-approved,²⁷ and approved drugs have sometimes been withdrawn later.^218,220 See Not FDA-Approved to weigh FDA status alongside the evidence.