Cannabinoids and chronic pain

Chronic pain is one of the most common reasons people ask about medicinal cannabis in New Zealand. The question is not simply “does it work?”; the evidence is mixed, the formulations are not interchangeable, and the legal pathway is narrower than most people assume. Below is a usable method for thinking about cannabinoids and chronic pain, a checklist to apply before your next appointment, and the regulatory boundaries that apply in New Zealand.

Cannabinoids and chronic pain: Medicinal cannabis: what the law actually allows

New Zealand’s Medicinal Cannabis Scheme, established under the Misuse of Drugs Act, legalises access to cannabis-based medicines only through a prescription from a medical practitioner. It is not a general licence to use cannabis. Formulations must meet Good Manufacturing Practice (GMP) standards and be approved by the Ministry of Health (New Zealand Ministry of Health, 2020). The scheme is administered by the Medicinal Cannabis Agency (MCA), which sits within Medsafe.

The common misunderstanding is that “legal medicinal cannabis” means a patient can smoke raw plant material or buy unregulated goods. In New Zealand, the legal option is a manufactured pharmaceutical. Even dried flower, where prescribed, is a GMP-certified pharmaceutical dispensed through a pharmacy, not a dispensary, not a “wellness” store, and not something you can grow or buy online.

What the evidence says

The strongest support for medicinal cannabis in chronic pain comes from systematic reviews of randomised controlled trials. A 2021 systematic review in the BMJ analysed 73 trials (n = 6,462) and found that, compared with placebo, cannabis-based medicines produced a clinically meaningful reduction in pain (≥30%) in about 1 in 6 more patients, but also increased the risk of short-term adverse events (dizziness, sedation, confusion) by about 1 in 12. The authors rated the certainty of findings as low to moderate for pain outcomes and noted that most trials lasted less than six months, so long-term harms remain unclear.

A 2023 network meta-analysis of 81 randomised trials in the BMJ compared cannabinoids with placebo for chronic non-cancer pain. It found a high probability that cannabis-based medicines produced a ≥30% pain reduction (number needed to treat ≈ 10), but the support for ≥50% pain reduction was less certain. The review also reported that 17% of people using cannabis withdrew due to adverse events, compared with 7% on placebo, a difference that matters when discussing long-term use.

How the New Zealand prescription pathway works

The New Zealand Medicinal Cannabis Scheme (MCS) began 1 April 2020. It is run by the Medicinal Cannabis Agency (MCA), which is part of Medsafe, under the Misuse of Drugs Act 1975. The scheme sets GMP standards and a list of approved options. Under the scheme, a medical practitioner can prescribe a medicinal cannabis preparation that meets GMP standards and has been notified to the Ministry of Health. As of 2020, the scheme does not allow patients to smoke raw plant material; medicines are manufactured pharmaceuticals (oils, capsules, or dried flower for vaporisation), and the dried flower is legal only when prescribed and dispensed through a pharmacy. The Misuse of Drugs (Medicinal Cannabis) Regulations 2019 govern this pathway; the scheme became fully operational in April 2020.

For a prescriber, the clinical decision begins with the NZ Formulary. The NZ Formulary (2023) includes medicinal cannabis monographs and the practical guidance that clinicians should start low, go slow, and review regularly. It does not mandate cannabis as first-line therapy; it is positioned as an option when standard treatments have failed or are poorly tolerated. The Ministry of Health’s Medicinal Cannabis Agency issues licences to import, manufacture and supply preparations, and maintains a public register of notified items. Prescribing itself is not restricted to specialists; any doctor can prescribe, but they must follow the Misuse of Drugs Act and the Medicinal Cannabis Scheme.