Thyer was an eminent apothecary in Manchester in the mid-eighteenth century. He was the son of Robert Thyer, a silk merchant, and was one of the original congregation of St John's Church. He was also a descendant of the surgeon Robert Thyer and his brother, Robert Thyrer, was librarian of Chetham's and a celebrated Jacobite. John Thyer was educated at Manchester Grammar School and established himself as an apothecary on Deansgate. Thyer was one of the first apothecaries to supply drugs to the Manchester Infirmary in 1753. Thyer died on 14 March 1798.