You must tell DVLA if you have dementia, a condition or treatment that could impact your fitness to drive. You can be fined up to £1,000 if you don’t tell DVLA about a medical condition that affects your driving. You may be prosecuted if you’re involved in an accident as a result. For more information please visit GOV.UK.
The General Medical Council's guidance for Patients' fitness to drive and reporting concerns to the DVLA or DVA provides information for doctors and clinical professionals on how to speak to your patient about the issue, what to do if you’re not sure about their fitness to drive, and the step to take if a patient continues to drive after you’ve advised them to stop.