What is the optimal THC:CBD ratio for medical use?

There is no single "optimal" ratio — the evidence suggests different ratios are appropriate for different conditions. What the research shows: (1) For cancer pain: balanced 1:1 THC:CBD (nabiximols/Sativex) outperforms THC-only in RCTs, with fewer adverse effects. The CBD appears to modulate THC's psychoactive effects via CB1 negative allosteric modulation. (2) For epilepsy: high-CBD, low-THC (Epidiolex is pure CBD). THC can actually lower seizure threshold in some epilepsy types. (3) For anxiety: high-CBD, low-THC. THC worsens anxiety at higher doses; CBD is anxiolytic. (4) For sleep onset: moderate THC may be more effective than CBD alone for acute sleep latency reduction. (5) For nausea: THC is the primary antiemetic; CBD adds limited benefit. The entourage effect hypothesis suggests whole-plant preparations may outperform isolates, but clinical evidence is limited. Practically, patients should start with high-CBD, low-THC ratios and titrate THC upward based on response and tolerability.