What are peptides and what are they used for?

Peptides, proteins and amino acids

An amino acid is the basic unit. Two or more joined by a peptide bond make a peptide; a long chain that folds into a stable structure is a protein. The line is a convention: FDA, for example, treats any chain of more than 40 amino acids as a protein and anything shorter as a peptide.

That is why BPC-157 (15 amino acids) and MOTS-c (16) are peptides, while tesamorelin, at 44, is technically a protein to FDA even though it is made by chemical synthesis.

What peptides are used for

In the body, many peptides act as messengers: they bind a receptor and change what a cell does. That leads to three very different uses that are worth keeping apart:

• Approved medicines. Insulin, semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are peptides or peptide derivatives approved by FDA. They need a prescription and are sold in pharmacies.
• Collagen and cosmetic peptides. Hydrolyzed collagen in supplements and copper tripeptide-1 in creams are consumer products with their own rules. They are not the same as a synthetic peptide in a vial.
• Research peptides. Molecules synthesized in a lab and sold as lyophilized powder in sealed vials, labelled for research use only. They are used in laboratory studies and are not medicines.

When social media says "peptides are for weight loss, skin or recovery", these three categories are usually being mixed up. The guides in this section separate what is approved, what has been published and what is not known.

What research peptides are

A research peptide is a synthetic compound sold for laboratory work: cell assays, analytical chemistry or studies in models. It is usually made by solid-phase synthesis, purified by HPLC and lyophilized (freeze-dried) so it is stable as a powder.

What separates reliable material from doubtful material is the lot documentation: a certificate of analysis (COA) that confirms identity by mass spectrometry and purity by HPLC. CaribePeptides publishes certificates in its COA library, and the guide how to read a COA explains what to check.

Research peptides are not approved for human or veterinary use. A "research use only" label does not make them supplements or medicines.

Are peptides safe, or are they steroids?

They are not steroids: steroids are molecules derived from cholesterol, with no amino acids. Whether a peptide is safe depends entirely on which peptide and for what. An approved medicine has clinical trials, a label listing its risks and manufacturing controls. Most research peptides have none of that in people: for several, FDA has said it knows of no human exposure data.

Quality matters too. FDA has warned about unapproved GLP-1 products with wrong doses or contaminants, and anti-doping analyses have found vials sold online that did not contain what the label said. That is why the lot COA is the first question, not the last.

The peptides Puerto Rico searches most

These are the compounds searched most on the island, each with its own guide or page:

• Retatrutide and tirzepatide: incretin receptor agonists.
• Tesamorelin: a growth hormone-releasing hormone analog.
• GHK-Cu, the copper peptide.
• MOTS-c: a mitochondrial-derived peptide.
• BPC-157 and TB-500.
• CJC-1295 and ipamorelin.