guide · one word, four kinds
Peptides
The collagen in your cupboard is a peptide. So is your wrinkle cream, so is Ozempic, and so is the vial someone is selling on Instagram. One word, very different purchases — here is which is which, and what the research says about each.
What a peptide actually is
A peptide is just a short chain of amino acids — the same building blocks proteins are made of, only fewer of them. That is the entire definition, which is why the word ends up on such wildly different products.
So “is it a peptide?” turns out to be the wrong question. The useful one is which kind you are holding, because a tub of collagen and a vial bought online have almost nothing in common beyond the chemistry class they belong to.
The ones you scoop into a drink
Collagen, whey, and a few others — proteins broken into smaller pieces so they absorb more easily. This is what most people mean when they say they take peptides, and some of it has genuinely good evidence behind it.
Sold for skin elasticity, joint comfort, hair and nails.
Sold for faster absorption and recovery than whole whey.
Sold for muscle buffering, anti-glycation, ageing.
Sold for stomach lining and gut repair.
Sold for antioxidant, detoxification, skin brightening.
The ones in your skincare
Serums and creams. You will find these on ingredient lists under names that look alarming and are not. The honest open question for most of them is how much gets through the skin at all.
Sold for skin firmness, wrinkles, wound healing, hair growth.
Sold for collagen stimulation, fine lines.
Sold for expression lines, marketed as a topical alternative to botulinum toxin.
The ones sold online for injecting
These are the ones your feed is probably showing you — sold for healing injuries, building muscle, or slowing ageing, usually labelled "for research use only". That label is doing legal work, not describing how they are used. Worth reading the note below before you buy any of them.
Sold for injury recovery, flexibility, inflammation.
Sold for growth hormone release, recovery, body composition.
Sold for growth hormone and igf-1, muscle, sleep.
Sold for metabolic health, insulin sensitivity, endurance.
Sold for muscle repair and growth.
Sold for antimicrobial, chronic infection, biofilm.
The ones your doctor can prescribe
Ozempic and its relatives are peptides too. They went through full trials and approval, which is exactly what separates them from the group above.
Sold for type 2 diabetes and weight loss — prescription only.
Sold for type 2 diabetes and weight loss — prescription only.
Sold for type 2 diabetes and weight loss — prescription only.
Sold for osteoporosis — prescription only.
Sold for diabetes — prescription only.
If you are thinking about the injectable ones
One thing is worth knowing, because sellers describe it the other way round. The FDA keeps a list of substances it has flagged safety concerns about, and a second list of ones where somebody applied to have them allowed in compounded prescriptions and then withdrew the application. BPC-157, TB-500 and most of the others sit on that second list.
You will see that reported as them being cleared. It is closer to the opposite: nobody is asking for approval any more, so nobody is checking. It is not a verdict against them either — it is an absence of one, and that is genuinely different from a product that has been through trials.
If you are considering one of these, that is a conversation to have with a doctor rather than a comment section. They are also banned in competitive sport.
Why most of these have no rating yet
We rate something only after reading the studies behind it one by one. Three of the 34 here have been through that — collagen, zinc carnosine and glutathione — and they are linked above. The rest are on our list.
Listing something is not recommending it, and a blank is not a criticism. We would rather show you the gap than fill it with a guess.
Check a bottle you already own →FDA statuses read from Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (FDA, page content current as of 22 April 2026), checked 18 August 2026. Peptide hormones, growth factors and their mimetics are also prohibited in sport at all times under section S2 of the WADA Prohibited List.