He was educated at Royal High School and Edinburgh University, and having obtained his medical diploma by 1810, he acted as surgeon on board a man-of-war commanded by Admiral Sir Charles Napier, and saw active service on the Portuguese coast, during the Peninsular War, under Lord Exmouth.
He was professor of surgery at the Royal College of Surgeons of Edinburgh and senior surgeon at the Royal Infirmary of Edinburgh. He performed the first ovariotomy in Britain in 1825. One of his pupils was Charles Darwin.
Besides authoring an early work on the dangers of tobacco, The Use and Abuse of Tobacco, Lizars published a number of important and beautifully illustrated anatomical texts in the early nineteenth century.
Lizars introduced into surgery the operation for the removal of the upper jaw, and his name survived in the "Lizars lines". In the 1830s he is listed as living at 38 York Place in Edinburgh"s New Town.
Lizars claimed in print in 1838 that James Syme had endangered a patient"s life and ruined his health by want of care in averting hemorrhage. Syme had been an unsuccessful competitor for the post held by Lizars.
Syme replied with a lawsuit, in which he claimed damages for false and malicious statement.
The suit was successful, but with token damages only. Syme, however, had a probable role in dissuading the College of Surgeons from re-electing a professor of surgery when Lizars"s tenure of the office finished. Lizars published further criticism, in 1851, of external urethrotomy as practised by Syme.
Syme retaliated with a comprehensive personal attack.
This time Lizars sued, and lost. Lizars had become eccentric, and was unable to obtain further public appointment.
And his private practice declined. Lizars died suddenly on 21 May 1860.
The suspected cause was an overdose of laudanum.