Peptides: separating approved medicines from research chemicals

What a peptide is

A peptide is a short chain of amino acids joined end to end. Longer chains, conventionally above about fifty, are called proteins. That is the entire distinction, and it is a matter of length rather than of kind.

Insulin is a peptide. So is semaglutide. So is growth hormone, so are the hormones that regulate your appetite, your thirst and your stress response. Describing something as "a peptide" says almost nothing about what it does or whether it is safe — roughly as much as describing a substance as "a powder".

Which peptide medicines are registered in Costa Rica

Several, and they are the ones most people have heard of:

• semaglutide — Ozempic, Wegovy
• liraglutide — Saxenda
• tirzepatide — Mounjaro
• somatropin — Norditropin, a recombinant growth hormone

Each holds Costa Rican sanitary registration, is imported by a licensed distributor, and is dispensed by pharmacies against a prescription.

Which are not

The Ministry of Health's warning of 23 July 2026 names several unregistered peptides specifically: retatrutide, tesamorelin, BPC‑157, TB‑500 and GHK‑Cu. A separate 2025 alert covers SARMs — ostarine, testolone, ibutamoren, stenabol — which are not peptides at all but are sold through the same channels and the same marketing.

These are the compounds that dominate the online peptide trade. They are also the ones most often named on clinic websites, because they are the ones a clinic can obtain without a distributor relationship.

"Research use only" is the whole argument

Unregistered peptides are almost always sold with research use only, or not for human consumption, printed on the vial. That wording is not a disclaimer somebody added out of caution. It is the legal basis on which the product can be sold at all, because a substance sold for laboratory research is not being sold as a medicine and therefore needs no medicines approval.

Which means nobody has assessed four things:

• Identity — whether the vial contains what the label says
• Dose — whether it contains the stated quantity, and the same quantity as the last vial
• Sterility — which matters absolutely for anything injected
• Purity — what else came along with it from the synthesis

Independent testing of this market has repeatedly found vials under-dosed, over-dosed, or containing a different compound. There is no recall mechanism, because there is nothing to recall from.

Compounding is a third category, and it is legal

Between the two sits magistral preparation: a licensed pharmacy compounding a medicine for one named patient against one individual prescription. Costa Rica permits this, and the July 2026 warning confirms it. Sterile injectable compounding requires a pharmacy working to USP <797> standards, which is a real and auditable thing.

What the same warning prohibits is manufacturing to hold inventory, selling at scale, and advertising the compounded product to the public. So a compounded medicine prepared for you is legitimate. A compounded medicine offered from a price list is not, whatever it is called.

How to tell which one you are being offered

Three questions settle it, and none of them requires any chemistry:

1. Does it have a brand name and a sanitary registration number, or a code number?
2. Does it come from a pharmacy, or by courier?
3. Does the vial say research use only?

Approval is not bureaucracy attached to an otherwise identical product. It is the record that somebody checked, and the reason there is somebody to hold responsible if they did not.

Why this clinic only uses the registered list

Partly because the registered medicines have the strongest evidence behind them, and partly for a simpler reason: we cannot verify what is in an unregistered vial, and neither can you. We would rather prescribe a narrower list we can stand behind.