Certificate of Analysis (CoA): What UK Cannabis Patients Need to Know

What Is a Certificate of Analysis (CoA) for Medical Cannabis?

A Certificate of Analysis (CoA) is a laboratory document that confirms the chemical composition of a medical cannabis product. Every licensed medical cannabis product available through UK pharmacies should come with a CoA from an independent, accredited laboratory.

Understanding how to read and verify a CoA is an important skill for UK patients — it helps you confirm you are receiving what you are prescribed, understand what you are putting into your body, and identify any quality or safety concerns.

Why CoAs Matter for UK Medical Cannabis Patients

Medical cannabis in the UK is tightly regulated, but product variation is real. CoAs provide independent verification of:

• Cannabinoid content: Actual THC and CBD concentrations — confirming the product matches its label claims.
• Minor cannabinoids: CBG, CBN, THCV, CBC levels — relevant to therapeutic effect and for patients sensitive to specific cannabinoids.
• Terpene profile: The aromatic compounds that influence the entourage effect and product character.
• Contaminants: Pesticides, heavy metals, residual solvents, mycotoxins, and microbial contamination — safety markers that matter particularly for immunocompromised patients.

Without a CoA, you cannot independently verify that a product is safe, correctly labelled, or appropriate for your condition.

How to Read a Cannabis CoA

Section 1: Product Identification

Verify that the product name, batch number, and strain name match your dispensed product packaging. Batch numbers are critical — a CoA is only valid for the specific batch you received. If the batch number does not match, the document cannot be relied upon.

Section 2: Cannabinoid Profile

This is the most important section for most patients. Key values to check:

• Total THC: Expressed as a percentage of dry weight (for flower) or mg/ml (for oils). UK T-class flower designations (T10, T20, T25) refer to approximate THC percentages.
• Total CBD: Reported similarly. C-class designations (C4, C8) indicate CBD percentage.
• THC:CBD ratio: Relevant to therapeutic effects and side effect profile — particularly for anxiety-prone patients.
• THCA vs Delta-9 THC: THCA is the acidic precursor that converts to active THC on heating (decarboxylation). For vaporised flower, total THC should account for this conversion.

Section 3: Terpene Profile

Terpenes contribute to therapeutic effects through the entourage effect and influence the taste, aroma, and experience of cannabis. Common terpenes and their associated effects:

• Myrcene: Sedative, muscle relaxant. High in many indica-dominant strains.
• Limonene: Uplifting, anti-anxiety properties.
• Linalool: Calming, found in lavender and many cannabis varieties.
• Caryophyllene: Anti-inflammatory, interacts directly with CB2 receptors.
• Pinene: May counteract some memory effects of THC, bronchodilatory.

Learn more in our terpenes guide for UK patients.

Section 4: Contaminant Testing

This section confirms the product has been tested for and passed limits for:

• Pesticides: EU and UK pharmacopoeial limits apply to licensed products.
• Heavy metals: Lead, mercury, cadmium, arsenic — particularly relevant for soil-grown cannabis.
• Mycotoxins (aflatoxins, ochratoxin): Mould-derived toxins that pose serious health risks, particularly for immunocompromised patients.
• Microbial contamination: Total yeast and mould counts, absence of E. coli and Salmonella.
• Residual solvents: Relevant for extraction-based products (oils, concentrates).

How to Request Your CoA

UK patients can request the CoA for their prescribed product from:

• The dispensing pharmacy at the point of supply — pharmacies are required to hold these documents.
• The product manufacturer or UK importer — batch-specific CoAs are increasingly available on manufacturer websites.
• Your prescribing clinic — good clinics will proactively share CoAs for products they prescribe.

If a pharmacy or clinic is reluctant to provide a CoA, this is a serious concern and should be raised as a formal complaint.

Red Flags on a Cannabis CoA

• Batch number does not match your product packaging.
• Test date is more than 12 months old for the specific batch.
• Laboratory is not ISO 17025 accredited or UKAS-recognised.
• Contaminant sections are missing entirely — not just "pass/fail" noted.
• Cannabinoid values differ significantly (more than ±10%) from product label claims.

Summary

• Every licensed UK medical cannabis product should have a batch-specific CoA from an accredited lab.
• Verify batch numbers, cannabinoid values, terpene profile, and contaminant testing results.
• Request your CoA from your pharmacy or clinic for each new batch supplied.
• Use CoA data alongside strain profiles and product listings to make informed treatment choices.