[8] Saladino d'Ascoli, a 15th-century Italian physician, claims that the medieval electuary, a pasty mass consisting of a drug mixed with sugar and water or honey suitable for oral administration,[9] known as opopira,[10] a complex compound medicine used to treat diverse maladies including paralysis, was invented by Cosmas and Damian.

However, according to legend they stayed true to their faith, enduring being hung on a cross, stoned, shot by arrows, and finally suffered execution by beheading.

[5] The veneration of Cosmas and Damian quickly spread beyond Constantinople; accounts of their martyrdom were rewritten by various authors such as Andrew of Crete, Peter the Wonderworker, Theodore II Laskaris, and a certain Maximus c. 1300.

[8] There, following his cure, ascribed to the intercession of Cosmas and Damian, Justinian, in gratitude also built and adorned their church at Constantinople,[8] and it became a celebrated place of pilgrimage.

At Rome, Pope Felix IV (526–530) rededicated the Library of Peace (Bibliotheca Pacis) as a basilica of Santi Cosma e Damiano in the Forum of Vespasian in their honour.

What are said to be their skulls are venerated in the Convent of Las Descalzas Reales of the Clares in Madrid, where they have been since 1581, the gift of Maria, daughter of Emperor Charles V. They had previously been removed from Rome to Bremen in the tenth century, and thence to Bamberg.

He personally "miraculously" retrieved the relics of the holy physicians Cosmas and Damian, which were allegedly immured and forgotten in the choir of the Bremen Cathedral.

The shrine, made from carved oak wood covered with gilt and rolled silver is considered an important mediaeval gold work.

They are also invoked in the Litany of the Saints, and in the older form of the Roman rite, in the Collect for Thursday in the Third Week of Lent, as the station church for this day is Santi Cosma e Damiano.

The two-day festival includes music (La Banda Rosa), much Italian food, Masses and processions through the streets of East Utica.

This classification of saints is unique to the Eastern Church and refers to those who heal purely out of love for God and man, strictly observing the command of Jesus: "Freely have you received, freely give", (« Δωρεὰν ἐλάβετε, δωρεὰν δότε... » Matthew 10:8) While each of the Unmercenaries has his own feast days, all are commemorated together on the first Sunday in November, in a feast known as the Synaxis of the Unmercenary Physicians.