Patients who use medical cannabis containing THC may experience dizziness, fatigue and difficulty concentrating. This can result in impaired judgement as well as difficulty in performing skilled tasks. Until a patient is aware of how they will be affected by medical cannabis products, they should avoid activities that depend on coordination, quick decision-making and remaining alert. People who frequently/routinely need to drive or operate heavy machinery should not use cannabis medicine as they are at a higher risk of having an accident.