Article 12 - How to Read a Certificate of Analysis: What Your Flower Label Doesn't Tell You

A flower label gives you a headline. A Certificate of Analysis, or COA, gives you a much wider view of a specific batch.

For patients using prescribed cannabis-based medicines, that distinction matters. A label may show the main cannabinoid percentages and a product name. A COA can provide additional information about identity, potency, minor cannabinoids, terpenes, contaminants, testing methods, and the batch that was actually analysed.

A COA is not a guarantee of a clinical outcome. It is a laboratory report about a particular sample from a particular batch. Used properly, it helps patients and clinicians ask better questions.

What is a Certificate of Analysis?

A Certificate of Analysis is a document issued after laboratory testing. It should identify the product or sample, the batch or lot, the tests performed, the results, and the laboratory responsible for the analysis.

The document may be supplied by a manufacturer, distributor, prescribing clinic, or pharmacy. Its format can vary. The key question is not whether the document looks impressive. The key question is whether it is specific, traceable, and clear about what was tested.

Start with the identity and batch details

Before reading the numbers, check that the COA relates to the product you actually have. Look for:

• Product name or identification
• Batch or lot number
• Sample or production date
• Testing date
• Laboratory name
• Report number or document reference

The batch number on the COA should match the batch number on the packaging or the product documentation. A report for a different batch may be interesting, but it does not confirm the composition of the medicine in front of you.

Understanding cannabinoid results

Most patients first look for THC and CBD. Those figures are important, but they are only part of the report.

Check whether the report gives a percentage, a concentration, or a total amount. These are not interchangeable. A percentage may describe the proportion of a substance by weight. A concentration may be expressed in a different unit. Follow the document's definitions and do not compare figures from different formats without understanding the measurement.

Look for minor cannabinoids where they are reported. Depending on the product, the report may include compounds such as CBG, CBC, or other cannabinoids. A compound appearing on a report does not automatically establish a specific therapeutic effect. It simply describes what the laboratory detected and measured.

Also check whether the result is presented as an exact value, a range, or a value below a reporting limit. A result marked as not detected does not necessarily mean that the compound is absolutely absent. It may mean that it was below the method's ability to measure it reliably.

Reading the terpene section

Terpenes contribute to aroma and flavour, and they are often discussed in relation to the entourage effect. A COA may list individual terpenes and their measured amounts.

Terpene results can help describe the batch, but they should not be treated as a promise that the product will create a particular mood, symptom response, or clinical outcome. The effect experienced by a patient also depends on dose, route, delivery method, physiology, and other medicines.

Terpenes can also change during cultivation, storage, handling, and preparation. This is one reason to treat a COA as a useful snapshot of a tested batch, not as a permanent description of every future batch.

Checking contaminant testing

A responsible COA should make clear which contaminant categories were tested. Depending on the product and testing programme, these may include:

• Microbial contamination
• Mould or yeast
• Heavy metals
• Pesticide residues
• Residual solvents
• Foreign matter
• Moisture or water activity

Look for a clear result, limit, or pass and fail status for each relevant category. A report that lists only cannabinoid potency does not tell you whether the same sample was checked for other contaminants.

For inhaled products, cleanliness and consistency matter particularly because the route of administration can affect how the patient is exposed to the material. Patients should ask their prescribing team or pharmacist if a report is unclear or if a result appears outside the stated specification.

What the laboratory information tells you

Look for the laboratory name, report date, test methods, and any accreditation or quality information provided. A serious report should make it possible to understand who tested the sample and what was measured.

Different methods can produce results that are not directly comparable. A difference between two reports does not automatically mean that one product is better or that something has gone wrong. It may reflect the sample, the batch, the method, or the way the result is reported.

If the COA uses technical abbreviations or unexplained symbols, ask the supplier, pharmacist, or prescribing clinic for clarification rather than guessing.

What a COA cannot tell you

A COA cannot predict exactly how a medicine will affect an individual patient. It cannot establish the right dose for you, replace a prescription, or confirm that a product will treat a particular condition.

It also cannot prove that a higher number is better. A higher THC percentage, a larger terpene total, or a longer list of detected compounds is not automatically a better clinical choice. Suitability depends on the prescribed medicine, the patient's response, the treatment plan, and professional guidance.

A practical patient checklist

When you receive or review a COA, ask:

• Does the batch number match my product?
• When was the sample tested?
• Which cannabinoids and terpenes were measured?
• Are the units and reporting limits explained?
• Which contaminant categories were tested?
• Are the results clearly marked as within specification?
• Is the laboratory and test method identified?
• Who can explain anything I do not understand?

Keep the COA with your product information and bring questions to your pharmacist or prescribing clinician. If your product changes, check whether the batch or formulation has also changed.

The honest conclusion

A flower label is a starting point. A batch-specific COA can provide a more detailed picture of what was tested, how it was measured, and whether the sample met the stated specification.

Read it as evidence about composition and quality testing, not as a promise of treatment. The most useful COA is one that is traceable, understandable, and connected to the exact batch you are using.

Sources and further reading

Laboratory reports use technical methods and reporting limits that can differ between products and laboratories. For questions about a specific medicine, batch, result, or clinical decision, speak with your prescribing clinician or pharmacist.