Cannabis and THC Dosing Regimen Recommendations

General Dosing Principles

The American Society of Clinical Oncology recommends starting with the lowest possible dose and titrating slowly upward based on clinical response and tolerability, following a "start low, go slow" principle to minimize adverse effects 1, 2
Allow sufficient time between dose increases to properly assess effects, as oral THC onset may take 30 minutes to 2 hours, to minimize adverse effects 1
Avoid taking cannabis products with high-fat meals, as this significantly increases cannabinoid absorption and may exacerbate side effects, according to the American Society of Clinical Oncology 1, 2
Be cautious about "stacking doses" (taking additional doses before the first has taken effect), which can lead to excessive adverse effects, as warned by the American Society of Clinical Oncology 1

For oral CBD, the American Society of Clinical Oncology recommends avoiding doses of 300 mg or more per day due to risk of reversible liver enzyme abnormalities, with a strength of evidence based on clinical trials 3, 4
For cannabis extract (1:1 THC:CBD ratio), the American Society of Clinical Oncology suggests a dose of 1-4 self-titrated capsules of oral THC 2.5 mg:CBD 2.5 mg three times daily for refractory nausea/vomiting, with a moderate strength of evidence 4, 5

For perioperative patients consuming >1.5 g/day of inhaled cannabis, >300 mg/day CBD oil, or >20 mg/day THC oil, the British Journal of Anaesthesia recommends considering additional anesthetic requirements during induction and maintenance, with a high strength of evidence 6, 7
For elderly patients, the American Geriatrics Society recommends starting with lower doses (e.g., 2.5 mg once daily for dronabinol) and monitoring more closely for adverse effects due to reduced drug clearance, with a moderate strength of evidence 2

The American Society of Clinical Oncology recommends monitoring for common adverse effects including euphoria, drowsiness, dizziness, vertigo, and hallucinations, with a high strength of evidence 1
Be aware of potential drug interactions, particularly with medications metabolized by CYP3A4, CYP2C9, and CYP2C19, as warned by the American Society of Clinical Oncology, with a moderate strength of evidence 1, 2
High-risk drug interactions include warfarin (very high risk), buprenorphine, and tacrolimus (high risk), according to the American Society of Clinical Oncology, with a high strength of evidence 1

The American Society of Clinical Oncology recommends using cannabis with caution in patients receiving immunotherapy due to potential interference with treatment efficacy, with a moderate strength of evidence 3