You must tell the Driver and Vehicle Licensing Agency (DVLA) if you have ever had, or currently suffer from a medical condition that may affect your vehicle control.
If you have a medical condition which has become worse since your licence was issued or you develop a new medical condition, you must inform the DVLA of your condition, as it may affect your fitness to drive. Failure to do so is a criminal offence and is punishable by a fine.
For full details of the medical conditions DVLA need to know about, please visit the DVLA website – there is a link to the website in the Useful Links page.