Medical cannabis side effects & safety

Common, dose-related effects

The most frequently reported effects — largely THC-mediated and usually reversible with dose reduction — include dizziness or light-headedness, somnolence, dry mouth, cognitive slowing or impaired concentration, altered appetite, and (at higher doses) anxiety, disorientation or tachycardia. CBD-predominant preparations are more often associated with fatigue, diarrhoea and appetite change.

Cautions and higher-risk groups

Exercise particular caution — and weigh benefit against risk — in patients with a personal or family history of psychosis, significant cardiovascular disease, hepatic impairment, or a history of substance-use disorder, and in pregnancy or breastfeeding. THC-containing products can impair driving and operation of machinery. Decisions should follow current product labelling and local regulation.

Minimising harm

A start-low, go-slow titration is the single most useful safety measure: begin at a low dose, increase gradually, and review effect and tolerability before each step. Preferring higher-CBD ratios where appropriate, dosing in the evening when sedation is expected, and reconciling concomitant medicines all reduce risk. See the dosage guide and drug interactions.

Monitoring

Review early after initiation and after each dose change: therapeutic response, adverse effects, functional impact and (where relevant) mood and cognition. Document indication, formulation, ratio and dose. Advise patients how to recognise and respond to over-sedation or acute anxiety.

Frequently asked questions