Plenty of people using cannabis do not tell their doctor. The reasons are understandable: legal worry, fear of judgement, or the assumption that it does not matter because it is a plant.
There are concrete situations where the omission changes clinical decisions, and one of them can affect your safety during surgery.
Anaesthesia Is the Most Compelling Reason
This is the argument that convinces people who dismiss everything else.
Regular cannabis users may require higher doses of anaesthetic agents, including propofol, to reach and maintain adequate sedation. Anaesthetists have reported this, and it is a genuine dosing consideration rather than a theoretical one.
Two further concerns:
Anaesthetic dosing is titrated to effect, and an anaesthetist who knows about your cannabis use plans accordingly. One who does not may under-dose initially. Being awake or aware during a procedure is a serious outcome, and the fix is a sentence before surgery.
Most guidance suggests avoiding cannabis for a period before elective surgery, so ask your team how long.
Interactions Are the Everyday Reason
CBD inhibits several cytochrome P450 enzymes including CYP3A4, CYP2C19, CYP2C9 and CYP2D6, which clear a large share of prescription medications. Interactions with practical consequences include:
There is also one nobody expects: smoking cannabis induces CYP1A2 through combustion products, lowering levels of clozapine, olanzapine and theophylline. Stopping smoking can push those levels up toward toxicity.
Other Situations Where It Matters
What To Actually Say
Vague disclosure is not much use. Bring specifics:
1. What you use. Flower, edibles, vape, tincture, topical, CBD only. 2. How much. Milligrams if you know them, otherwise a description such as one or two joints per evening. 3. How often. Daily, weekends, occasionally. 4. How long you have been using at this level. 5. Why. Sleep, pain, anxiety, recreation. All legitimate answers. 6. Route, since smoked, eaten and topical have different implications.
A workable opening: "I want to mention that I use cannabis, because I know it can interact with medications. I use about X, in this form, this often, mainly for Y."
Framing it as relevant clinical information rather than a confession sets the tone.
About Confidentiality and Judgement
Medical confidentiality applies to cannabis as to anything else. Rules vary by jurisdiction and setting, and if you have specific worries, asking directly how the information will be recorded is reasonable.
On judgement: attitudes have shifted considerably, and most clinicians are far more interested in interactions and safety than in moralising. If you do encounter dismissiveness, that is a reason to consider a different clinician rather than to withhold information from the next one.
Worth knowing too: medical training on cannabis has historically been limited, so some clinicians will not know much. That is not a reason to skip telling them, since they still know your medications.
If You Want Cannabis Considered as Treatment
Come with something specific. Which symptom, what you have already tried, what your goal is, and what you have read. Ask about interactions with your current medications, what route they would suggest, what dose to start at, and what would tell you it is not working.
If your clinician cannot help, ask for a referral rather than self-directing. Pain, palliative care and neurology services increasingly have experience here.
Bottom Line
Disclose cannabis use because it changes clinical decisions. Anaesthetic dosing may need to be higher, CBD inhibits liver enzymes that clear many prescriptions, and smoking induces an enzyme that lowers clozapine and olanzapine levels. Bring specifics about what, how much, how often and why, and treat it as clinical information rather than a confession.
Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before making any health-related decisions.