Pharmacokinetic interactions (CYP450)
CBD in particular can inhibit several cytochrome P450 enzymes (including CYP3A4 and CYP2C19), potentially raising plasma levels of co-administered substrates; THC is also metabolised by CYP enzymes. Clinically important examples to review include anticoagulants such as warfarin (monitor INR), certain anti-epileptics, and other narrow-therapeutic-index CYP3A4/2C19 substrates. Where an interaction is plausible, consider closer monitoring or dose adjustment of the co-medication.
Pharmacodynamic interactions
Additive effects are often the more predictable risk: CNS depressants (benzodiazepines, opioids, sedating antihistamines, alcohol) can compound sedation and psychomotor impairment; agents that affect heart rate or blood pressure may interact with THC's cardiovascular effects. Counsel patients accordingly, particularly around driving.
A practical approach
Take a full medicines history including over-the-counter and herbal products; flag narrow-therapeutic-index drugs and CNS depressants; start low and titrate slowly; and monitor after initiation and dose changes. Consult current product information and an up-to-date interaction reference for any specific pairing — this page is an orientation, not a substitute for that check.
Put this into practice
Move from reference to a compliant prescription and proforma invoice with the EndoCann clinic tools.