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Key Drug Interactions
- Cannabis metabolised via CYP3A4 and CYP2C9 — many prescription medications use the same enzymes
- CBD is a potent inhibitor of CYP2C19 and CYP3A4
- Blood thinners (warfarin): CBD can increase anticoagulant effect — INR monitoring essential
- Antiepileptics: CBD significantly increases clobazam levels
- Immunosuppressants (tacrolimus, cyclosporine): levels may increase with cannabis co-administration
Always disclose all medications at your cannabis consultation. Drug interactions are a primary clinical consideration.
Safe and Lower-Risk Combinations
- Paracetamol: no significant interaction expected
- NSAIDs: generally safe to combine with cannabis
- Most physiotherapy medications: no significant interactions
- Inhaled salbutamol or asthma inhalers: no clinically significant interaction
- Additive CNS depression with sedatives — dose reduction may be needed
Most drug interactions with cannabis are manageable with dose adjustment, but disclosure of the complete medication list is non-negotiable.
