A peptide is a short chain of amino acids. That one sentence covers a prescription medicine, a tub of collagen and a face serum, which is why the word confuses people. This guide explains what peptides are, what they do, and which kinds you will meet in Canada.
What are peptides? What is a peptide?
Amino acids are the building blocks of protein. Link two or more of them together with peptide bonds and you have a peptide. Your body makes thousands of different peptides and uses many of them as messengers: they travel in the blood, attach to a specific receptor on a cell and tell it to do something. Insulin, which moves glucose from the blood into cells, is a peptide hormone. So is oxytocin.
Peptide vs protein, and what’s a polypeptide?
| Term | Roughly how long | Example |
|---|---|---|
| Dipeptide, tripeptide | 2 or 3 amino acids | Copper Tripeptide-1 in skincare |
| Oligopeptide | Up to about 20 | Oxytocin (9 amino acids) |
| Polypeptide | About 20 to 50 or more, in one chain | Insulin’s two chains have 21 and 30 |
| Protein | Usually more than 50, folded into a 3D shape, often several chains | Collagen, haemoglobin |
What are polypeptides? A polypeptide is simply a longer peptide: one continuous chain of many amino acids. A protein is one or more polypeptides folded into a working shape. The cut-offs are conventions, not hard rules, and scientists use “peptide” loosely for the shorter chains.
What do peptides do in the body?
- Hormones. Many hormones are peptides that regulate glucose, digestion, growth, water balance and reproduction.
- Signals between cells. Peptides help coordinate the immune system, inflammation and tissue repair.
- Nerve messengers. Neuropeptides such as endorphins act in the brain and nerves.
- Defence. Antimicrobial peptides on the skin and in the gut help control bacteria.
Types of peptides sold in Canada
For practical purposes there are three types of peptides you can legally get in Canada, and each is regulated differently.
Peptide medications
Prescription drugs reviewed and authorized by Health Canada, each with a DIN. They include semaglutide, tirzepatide, teriparatide, octreotide and desmopressin. A licensed pharmacy dispenses them on a prescription. See medications.
Supplement peptides
Mainly collagen peptides, sold as natural health products with an NPN. No prescription needed. Collagen peptides guide.
Cosmetic peptides
Signal peptides in creams and serums that improve the look of skin. Peptide serums and copper peptides.
A fourth group, injectable vials sold online as research chemicals, is not authorized for sale in Canada. Our guide to peptides in Canada covers what is legal and why.
Why are so many new medicines peptides?
Because peptides fit their receptors precisely, they can be designed to switch one specific signal on or off. The drawback is that the gut digests most peptides like any other protein, so many peptide medications are injected, usually with a pre-filled pen, or modified so they last longer in the body. A few can now be taken as tablets or nasal sprays.
Do peptide pills work?
Mostly, no, and the reason is digestion. Your stomach and gut break proteins and peptides down into single amino acids and very short fragments before absorbing them, so a peptide swallowed as a capsule rarely reaches the bloodstream intact. That is why most peptide medications are injections. The authorized exceptions are specially engineered: a semaglutide tablet made with an ingredient that helps it cross the stomach wall, and desmopressin made as a tablet that melts under the tongue. Both are prescription products.
Collagen is the one peptide pill or powder that makes sense as food. It is meant to be digested: you take it for its amino acids and small collagen fragments, the way you would any protein. Peptide pills sold online with promises of injection-like results, by contrast, have no authorization and no good evidence behind them.
Peptides for women: what is different?
Peptides for women fall into the same three groups as for anyone else. The differences are practical, not separate products:
- Pregnancy and breastfeeding. Many prescription peptide medications are not used during pregnancy. Tell your prescriber if you are pregnant, breastfeeding or planning a pregnancy, and ask a pharmacist before starting a supplement or a new skincare active.
- Collagen. Collagen peptides are used by many women for the look of skin; trials report modest changes after 8 to 12 weeks. Choose a product with an NPN.
- Skincare. Cosmetic peptides are among the gentler actives, which is why pharmacists often suggest them when retinoids are on hold.
- Online claims. Be wary of “women’s peptide” blends sold as injections. They are not authorized in Canada, whatever the marketing says.
What are the best peptides?
There is no single list of best peptides, because the three kinds do different jobs:
- As a medication: the best peptide is the one a prescriber chooses for you after reviewing your health history. That is a clinical decision, not a shopping one. Start a consultation.
- For skincare: palmitoyl peptides, Acetyl Hexapeptide-8 and Copper Tripeptide-1 have the most cosmetic research behind them.
- As a supplement: collagen peptides, 2.5 g to 10 g a day, from a product with an NPN.
- For training: see our evidence review of peptides for muscle growth.
Are peptides safe?
It depends entirely on the product. Authorized medications have been tested in clinical trials and are made under inspected conditions; they still have side effects and are not right for everyone, which is why a prescriber and a pharmacist are involved. Licensed supplements and notified cosmetics are generally low risk when used as directed. Unauthorized injectables have none of these safeguards.
What is a peptide in simple terms?
A short chain of amino acids. The body uses peptides as messengers, and medicine, supplements and skincare all use them in different ways.
Are peptides the same as protein?
They are made of the same building blocks. A peptide is a short chain; a protein is a long chain, or several, folded into a three-dimensional shape.
Are peptides steroids?
No. Steroids are a different class of molecule built on a ring structure derived from cholesterol. Peptides are chains of amino acids.
Are peptides natural?
Your body makes its own. Peptides in medicines are manufactured to match or improve on natural ones; collagen peptides are made by breaking down animal collagen.
Do you need a prescription for peptides in Canada?
For peptide medications, yes. For collagen and cosmetic peptides, no. See where to buy peptides in Canada.
Reviewed by our pharmacist-in-charge. This page is general information, not medical advice.