Sts. Cosmas and Damian were twins born to Christian parents in Arabia during the third century. They lived in the region around the border between modern-day Turkey and Syria.
Cosmas was a physician and Damian an apothecary, and they both were renowned for their skill, as well as their refusal to charge for their services.
Their charity and Christian witness won many converts to the faith and earned them a place of prominence in the Christian communities of Asia Minor. Therefore, when the persecutions under Roman Emperor Diocletian began in the latter half of the third century, they were some of the first to be sought out for execution.
In 287, they were captured and ordered to deny their faith in Christ. They refused and underwent a series of tortures, including crucifixion, from which, miraculously, they remained unscathed. The torturers, weary of what they realized was the impossible task of forcing apostasy from their mouths, finally beheaded them both. Anthimus, Leontius and Euprepius, their younger brothers, who were inseparable from them throughout life, shared in their martyrdom.
As early as the 4th century, churches dedicated to the twin saints were established at Jerusalem, in Egypt and in Mesopotamia. Devotion to the two saints spread rapidly in both East and West.
They are invoked in the Canon of the Mass and the Litany of Saints. They are regarded as the patrons of physicians and surgeons and are sometimes represented with medical emblems.
— Catholic News Agency, Wikipedia