A certificate of analysis sounds like proof. Sellers treat it that way, waving it as the document that settles whether a product is legitimate. It is real evidence, and it is worth asking for. It is also narrower than its marketing suggests, and knowing exactly what it covers is the actual skill here.
What a COA is
A certificate of analysis, or COA, is a lab report. It is the output of testing performed on a specific batch, or lot, of raw material or finished product. It confirms what that tested sample actually contained at the time of testing. For a bulk ingredient like sermorelin acetate — the compound behind every formulation covered in what sermorelin is — that typically means three checks. Identity testing confirms this is actually sermorelin, not something else or nothing at all. Potency testing, also called assay testing, confirms what percentage of the labeled amount is actually present. And screens for microbial contamination, endotoxins, and heavy metals round it out, depending on how thorough the lab was asked to be.
This is not an optional nicety a pharmacy chooses to offer. FDA rules require it at the raw-material level for any compounded drug. A bulk drug substance must come with a valid certificate of analysis, from an establishment registered with FDA. That requirement applies to both 503A and 503B compounding [1]. The COA requirement does not start with the finished vial you receive. It starts one step earlier, at the raw sermorelin acetate powder the pharmacy bought before it touched a diluent.
What it actually proves
A COA proves that one tested sample, from one batch, met written specifications on the date it was tested. It says so according to the lab that ran the tests. That is a real and meaningful claim. It is also batch-specific and time-specific, not a permanent guarantee.
What it does not prove
It does not prove the vial in your hand came from the batch the certificate describes. That link depends on lot-number tracking actually being intact and checked, not assumed. It does not prove sterility of your specific vial after your pharmacy’s own compounding process touched it, either. Most bulk-ingredient COAs test the raw powder, not the pharmacy’s finished, compounded product. Contamination and endotoxin exposure are exactly the kind of risk covered in our side-effects article, and a raw-material COA alone does not rule that risk out downstream. A COA does not prove clinical safety or effectiveness either — it is a chemistry and microbiology document, not an outcome study. And it is not FDA approval of anything. Compounded sermorelin has no FDA-approved finished product to point to at all, a gap our FDA-approval article covers in full.
Why 503A vs. 503B actually matters here
Compounding pharmacies fall into one of two FDA-defined categories, and the difference is not just paperwork.
Section 503A covers a licensed pharmacist compounding in a state-licensed pharmacy, or a licensed physician. It generally runs against a valid prescription for a specific, named patient. Drugs compounded under 503A are explicitly exempt from federal current good manufacturing practice requirements [1]. That exemption is deliberate, built around a pharmacist filling an individual prescription rather than running a manufacturing line.
Section 503B covers outsourcing facilities: a different, FDA-registered category of compounder that can produce larger batches, sometimes without a patient-specific prescription in hand. Unlike 503A, drugs compounded under 503B are not exempt from cGMP [1]. That means 503B facilities meet the same current good manufacturing practice standard as conventional drug manufacturers. It is a materially higher, more systematically enforced bar than a 503A pharmacy has to meet, and it is the main practical reason the distinction matters to a buyer.
Sermorelin acetate currently sits in FDA’s Category 1, “Bulk Drug Substances Under Evaluation” — the list FDA maintains for substances nominated for 503B compounding [2]. That status is an open question FDA has not finished resolving, not a form of clearance.
What to actually look at
Given all of that, a COA is worth something specific, not everything. Check that the batch or lot number on the certificate matches the lot number on the vial you actually received. A certificate for a different batch tells you nothing about the vial in your hand. Check what was actually tested. Identity and potency are the baseline. Sterility and endotoxin testing are meaningfully more reassuring when present, and worth asking about directly when absent. Check the date, too — a certificate from a batch manufactured years ago says little about a fresh reconstitution. And check whether the pharmacy or seller produces one without being asked twice. Reading how other buyers describe that experience is part of what our provider reviews exist to capture. Sellers that publish milligram doses alongside sourcing details are gathered on the injections board.
The bottom line
A certificate of analysis is real evidence, tied to federal compounding law rather than a marketing flourish — bulk ingredients are required to carry one [1]. It proves a tested batch met specifications on a given date. It does not prove your specific vial matches that batch. It does not prove sterility of the finished product. And it is not FDA approval, because no FDA-approved finished sermorelin product exists to compare it to. Whether the compounder is a 503A pharmacy or a 503B outsourcing facility changes what standard that certificate sits behind. That is worth knowing before treating any one certificate as the whole answer.