The Initial Medical Consultation for Cannabis: What to Include

The Structure and Purpose of the IMC

• The IMC (Initial Medical Consultation) is the foundational appointment in cannabis prescribing
• It establishes diagnosis, treatment history, risk profile, and therapeutic goals before any prescription is issued
• NICE NG144 and GMC Good Medical Practice both inform the standard of care required
• A well-documented IMC protects both patient and prescriber if prescribing decisions are later scrutinised

The Initial Medical Consultation is the single most important encounter in the cannabis prescribing pathway. Its documentation creates the clinical justification for every subsequent prescription and must demonstrate that the patient has a confirmed diagnosis, has failed conventional treatments, does not have absolute contraindications, and has provided fully informed consent. Prescribers who do not invest time and rigour in the IMC expose themselves and their patients to significant clinical and legal risk.

Core Components of a Comprehensive IMC

• Presenting complaint and primary diagnosis: confirmed by referral letter or previous medical records
• Treatment history: document all prior treatments, doses, duration, and reason for discontinuation
• Contraindication screening: psychiatric history, cardiovascular history, personal and family history of substance use disorder
• Current medications list: full review for cannabis drug interactions, particularly CYP-mediated interactions

The treatment history component of the IMC is particularly critical. Prescribers must be able to demonstrate that cannabis is being considered after other appropriate treatments have been tried, unless there is a specific clinical reason why cannabis is being considered earlier in the treatment pathway. This “treatment-refractory” requirement aligns with the expectation of the major professional bodies and with the standard of care expected in clinical negligence proceedings.

Risk Stratification During the IMC

• Low risk: no psychiatric history, age 25–65, no cardiovascular disease, no substance use history, stable social circumstances
• Moderate risk: mild-moderate anxiety or depression, social cannabis use history, age 18–24 or over 65
• High risk: active psychiatric condition, significant cardiovascular disease, active substance use disorder, pregnancy
• Absolute contraindication: active psychosis, severe cardiovascular disease, severe respiratory disease (for inhaled preparations), pregnancy and breastfeeding

Risk stratification should not be a binary prescribe/do not prescribe decision for moderate-risk patients. Many moderate-risk patients can be safely prescribed cannabis with appropriate safeguards — more frequent review, lower starting doses, specific strain selection, or collaboration with a mental health team. The IMC documentation should reflect how the prescriber has weighed risk and benefit and what mitigating measures are in place.

Informed Consent: What Patients Must Understand Before Prescribing

• Psychoactive effects: nature, onset, duration, and variability between preparations
• Driving prohibition: UK law prohibits driving under the influence of cannabis regardless of medical use
• Dependency and withdrawal: real risks at standard therapeutic doses, particularly with high-THC preparations
• Pregnancy: cannabis is contraindicated in pregnancy and patients of childbearing potential must use effective contraception

Informed consent for cannabis prescribing must be documented in writing and ideally confirmed with a patient signature. The information provided must cover all material risks — not only common side effects but also rare serious events such as acute psychosis, cannabinoid hyperemesis syndrome, and cardiovascular events. A consent form developed with legal input provides the most robust documentation, and its use signals the seriousness of the prescribing framework.