This page is written to help you understand a health topic. It is educational and not a diagnosis, and nothing on it is personal medical advice. It cannot take account of your history, your examination or your own reports, and it is not a substitute for seeing a doctor.
Do not start, stop or change any medicine on the basis of this page. If your symptoms are severe, are getting worse, or match any of the urgent signs described above, seek medical care now rather than reading further. In an emergency, call your local emergency number or go to the nearest hospital.
Every page is written and reviewed by a registered medical practitioner and carries the date it was last reviewed. Medicine changes; if a page is old, treat it as a starting point for a conversation rather than as current guidance.