Reading labels and certificates

Every legal medicinal cannabis product in New Zealand carries two things you need to be able to read: the label on the container and the certificate of analysis (CoA) that accompanies the batch. This page gives you a method to interpret both, so you can compare products and understand what a prescription actually delivers. It does not rank brands or recommend doses.

What the label tells you

Under the Medicinal Cannabis Scheme, products dispensed in New Zealand are manufactured medicines, not herbal remedies. The label must show the product’s active cannabinoids in milligrams per gram (mg/g) or as a percentage. This is the single most important number to understand.

THC (delta-9-tetrahydrocannabinol) is the main psychoactive compound. CBD (cannabidiol) is the non-psychoactive compound. Labels list both as either mg/g or as a percentage. A product labelled “THC 25” means 25 mg of THC per gram of product. A 10:10 product means 10 mg/g THC and 10 mg/g CBD. The ratio, not the absolute number, usually determines the clinical effect. A 1:1 product is commonly used for balanced pain relief, while a high-THC product (e.g., 25:1) is used for breakthrough pain or sleep, and a high-CBD product (e.g., 1:20) is used for anxiety or inflammation without intoxication. This is not a recommendation; it is a description of how labels are read.

Batch numbers and expiry dates are the second thing to check. Every legal product has a batch number and expiry. The batch number ties the product to a Certificate of Analysis (CoA), which is a quality document issued by an independent lab. The CoA shows the actual measured cannabinoid content, terpene profile, and contaminant testing (pesticides, heavy metals, microbials). If a product label says “THC 25 mg/g” but the CoA for that batch says 22 mg/g, the CoA is the ground truth; labels can round or drift. In New Zealand, the Medicinal Cannabis Scheme requires every product to be tested and the results kept for inspection. If you are a patient, ask your pharmacist for the CoA for your specific batch; if you are a clinician, check the batch certificate before you prescribe. The batch number on the label is the key to traceability: it links the product you hold to the specific quality tests done on that batch, not to a generic product description.

Checklist for reading a label:

1. Find the batch number and expiry date. Every legal product has both. If either is missing, the product is not part of NZ’s Medicinal Cannabis Scheme.
2. Identify the form (flower, oil, capsule, powder). This determines onset and duration.
3. Check the active cannabinoids, usually listed as mg/g or %. For flower, THC and CBD are listed as percentages (e.g., “THC 22%”). For oils, they are listed as mg/mL (e.g., “THC 25 mg/mL”).
4. Look for the THC:CBD ratio. This is the single most useful number for predicting the experience. A 1:1 ratio is balanced; high-THC (e.g., 20:1) is more psychoactive; high-CBD (e.g., 1:20) is less psychoactive.
5. Note the batch number and expiry date. Products are batch-tested; the label’s numbers apply only to that batch.
6. Check the certificate of analysis (CoA). It should show actual measured cannabinoid content, not just label claims, plus tests for pesticides, heavy metals, mould, and residual solvents.
7. Confirm the product has a Medsafe approval number (e.g., “NZ” prefix) or is listed in the NZ Formulary. This is the only legal pathway.
8. Compare the THC:CBD ratio, not just total THC, because the ratio determines the experience more than the absolute amount.
9. For oils, check the concentration per mL (e.g., 25 mg/mL THC) and the total volume (e.g., 30 mL), then calculate total mg per bottle.
10. For flower, check the percentage of THC and CBD, and the batch number; potency varies between batches, so the label is a snapshot, not a promise.
11. Check the expiry date and batch number; products degrade over time, and the batch number lets you verify the certificate of analysis.
12. Verify the product is on the NZ Medicinal Cannabis Scheme’s product list; if it is not listed, it is not legally dispensable in New Zealand.
13. Ask the pharmacist for the certificate of analysis (CoA) for the specific batch; the CoA shows actual cannabinoid content, terpenes, and contaminant testing, not just the label claim.
14. Be wary of products that list only “CBD” or “THC” without a ratio; a 10:10 product contains equal amounts, a 20:5 has four times more THC than CBD; the ratio determines the experience more than the absolute numbers.
15. Store products correctly: oils degrade with heat and light; flower degrades over time. Check the expiry date and discard expired products. This is a safety issue, not a preference.
16. Do not mix with alcohol or other sedatives without discussing it with your prescriber first.

EXTERNAL SOURCES (only these): - NZ Medicinal Cannabis Agency (MCA), Official scheme documents (2023) - New Zealand Ministry of Health, Medicinal Cannabis Guidance (2023) - Medsafe, Product approval and quality standards (2023) - NZ Formulary, Cannabis monograph (2023) - Healthify, Medicinal cannabis patient information (2023) - New Zealand Medical Journal (NZMJ), systematic review on medicinal cannabis (2023)

The four things every label must tell you

Under New Zealand’s Medicinal Cannabis Scheme, every dispensed product label must show:

1. The active cannabinoid amounts, usually written as THC and CBD in mg/g or as a percentage (e.g., “THC 25 mg/g” or “10:10”).
2. The batch number, a unique code for that production run.
3. The expiry date, medicinal cannabis products degrade, especially oils.
4. The product name and form, e.g., “Medleaf THC25 Flower” or “Tilray 10:10 Oil”.

Medsafe (the New Zealand regulator) approves these products under the Medicinal Cannabis Scheme. The scheme requires products to meet GMP (Good Manufacturing Practice) standards and be approved by the Ministry of Health before they can be prescribed. You can check the official list of notified products on the Medsafe website.

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How to read the numbers on a label

Cannabinoid amounts are listed in milligrams per gram (mg/g) or as a percentage (%). They are not interchangeable at face value: 10 mg/g means 1% by weight, so a 10:10 product has 10 mg/g THC and 10 mg/g CBD.

The two numbers on a label (e.g., “10:10” or “25:1”) are the THC:CBD ratio. The ratio tells you the balance of psychoactive to non-psychoactive cannabinoids, but it does not tell you the total amount in the container. For example, a 10:10 oil in a 30 mL bottle contains 300 mg of THC and 300 mg of CBD, while a 10:10 flower is 1% THC and 1% CBD by weight.

How to read a label in 4 steps:

1. Find the THC and CBD amounts per gram or per millilitre (mg/g or mg/mL). This is the concentration, not the total dose.
2. Check the THC:CBD ratio. A 1:1 product (e.g., Tilray 10:10) means equal parts; a 25:1 product is THC-dominant; a 1:20 product is CBD-dominant.
3. Note the form (flower, oil, capsule) and the administration route. Flower is inhaled and acts in 5-10 minutes; oils are taken orally and act in 30-90 minutes.
4. Check the batch number and expiry date. These confirm the product is a specific manufactured lot and has not expired.
5. Verify the product is listed under the Medicinal Cannabis Scheme. If it does not appear in the NZ Formulary or is not approved by the Ministry of Health, it is not a legal prescription product.