The sibling site Compounding Explained reads a certificate of analysis line by line. This page is the buyer's version: you have the PDF a program sent you, you have five minutes, and you want to know whether it answers the question you asked. Ten checks, in order.
Check 1: is it about your vial?
Find the lot or batch number on the COA. Find the lot number on your dispensed label. They must match. If your vial has no lot number, stop here; that is the finding. If the COA has no lot number, it is a generic document, and the "third-party tested" claim it supports does not attach to what you received.
Check 2: is it about the finished product?
Read the product name at the top. A finished-product COA says something like "semaglutide 2.5 mg/mL injection, 2 mL vial" and names the pharmacy or outsourcing facility as the manufacturer. An ingredient COA says "semaglutide" (or worse, "semaglutide acetate") with a powder mass and names an API manufacturer. Programs regularly send the second when asked for the first. Only the first can show sterility, endotoxin and the actual concentration in your vial.
Check 3: does the strength match?
Concentration on the COA, in mg per mL, against your label. The assay result should be reported as a percentage of that label claim, with an acceptance range printed beside it. Compounded preparations commonly use 90 to 110 percent of label claim. A result outside the printed range is a failed lot regardless of what else the document says.
Check 4: is it the base, or a salt?
The identity line names the substance tested. Semaglutide and tirzepatide are the base forms in the approved products. The FDA has stated it is not aware of any basis for compounding with the sodium or acetate salt forms. If the COA identifies a salt, you have found something the program's website probably did not tell you.
Check 5: are the four core tests there?
For a sterile injectable: identity, assay (potency), sterility, and bacterial endotoxin. Sterility is USP chapter 71; endotoxin is USP chapter 85. pH is usually there too. A COA with identity and potency only has skipped the two tests that matter most for something you inject. Ask why.
Check 6: who ran the tests?
The laboratory should be named with an address. An independent lab is what "third-party tested" means; an in-house result is a result, but it is not third-party. You can look the lab up. If the lab is not named, you cannot.
Check 7: what are the dates?
Date of manufacture, date of testing, and beyond-use date. The beyond-use date on the COA should agree with the one on your label. Under USP 797, compounded sterile preparations carry short beyond-use dates; a multi-month vial with a beyond-use date many months out should have a stability study behind it, and you can ask for it.
Check 8: does anything say "pass" without a number?
A COA that lists "sterility: pass" is normal; sterility is a pass or fail test. A COA that lists "potency: pass" without the percentage is hiding the number. Ask for it.
Check 9: is there a signature or a release statement?
Someone at the pharmacy or facility released the lot. A quality or pharmacist signature with a date is normal. Its absence is not fatal but it is a question.
Check 10: does it match what the website promised?
Go back to the program's product page and its "how we test" claims. If the site says every lot is tested for potency, sterility and endotoxin by an independent lab, the COA should show exactly that. Where it shows less, the site's claim is larger than its evidence. That is what the rubric's supply-chain criterion scores, and it is why the evaluations record what each program says about testing next to what it will actually show you.
What a COA cannot tell you
Whether the product will work for you, whether the dose is right, whether the pharmacy's other lots were as good, whether the product was kept cold between testing and your door, or whether compounded medication is the right choice compared with the FDA-approved product. It is one lot, one date, one set of tests. That is worth having. It is not the whole answer.
Questions people ask
The program sent a COA with no lot number on it. Is it useless?
For matching to your vial, yes. Ask for the COA for the lot number printed on your dispensed label. If they cannot produce one, the third-party-tested claim on their site applies to something other than what you received.
What if the COA is from the ingredient supplier?
Then it describes the powder the pharmacy started with, usually from an overseas API manufacturer, and it says nothing about sterility, endotoxin or the final concentration in your vial. Useful as one document; not the one you asked for.
Is a passing COA proof the product is safe?
No. It is evidence the tested lot met the listed specifications when tested by the named lab. It does not cover what was not tested, how the product was stored after testing, or whether compounded semaglutide or tirzepatide is appropriate for you. Compounded drugs are not FDA approved.
Sources
- USP General Chapter 797, Pharmaceutical Compounding, Sterile Preparations Accessed September 4, 2026.
- FDA guidance: Current Good Manufacturing Practice for Outsourcing Facilities under Section 503B Accessed September 4, 2026.
- FDA: FDA's concerns with unapproved GLP-1 drugs used for weight loss (salt forms, dosing errors) Accessed September 4, 2026.
- Compounding Explained: what a certificate of analysis shows, line by line Accessed September 4, 2026.
Canonical URL: https://formblendsreviews.com/guides/how-to-read-a-coa. Written by the FormBlends editorial team. This page is educational and is not medical advice; see the medical disclaimer.