Why did blood and water come out of Jesus’ side when He was pierced?

Response

The Roman scourging that Jesus endured before his crucifixion typically involved 39 lashes, but it could have been more (Mark 15:15;John 19:1). The whip used, known as a flagrum, was made of braided leather thongs with metal balls and sharp bone fragments woven into or intertwined with the braids. The balls added weight to the whip, causing deep bruising upon impact. The bone fragments served to lacerate the flesh. With continued beating, the resulting wounds were so severe that the victim’s skeletal muscles, underlying veins, sinews, and bowels were exposed. This brutal beating was often fatal even before crucifixion could take place.

Those subjected to flogging would frequently enter hypovolemic shock, a condition characterized by low blood volume. Essentially, the individual would have lost so much blood that they would go into shock. The consequences would include:

1) The heart working overtime to pump insufficient blood.

2) The individual collapsing or fainting due to low blood pressure.

3) Kidney function shutting down to conserve body fluids.

4) Severe thirst as the body craved to replenish lost fluids.

Scriptural evidence suggests that Jesus indeed suffered hypovolemic shock from the flogging. While carrying His cross to Golgotha “And he bearing his cross went forth into a place called the place of a skull, which is called in the Hebrew Golgotha:”, (John 19:17), He collapsed, necessitating a man named Simon to either carry or assist Jesus in carrying the cross to the hill (Matthew 27:32–33); (Mark 15:21–22); (Luke 23:26). This collapse indicates that Jesus had low blood pressure. Another sign that Jesus suffered from hypovolemic shock was when He expressed thirst while on the cross “After this, Jesus, knowing that all things were now accomplished, that the scripture might be fulfilled, saith, I thirst.”, (John 19:28), showing His body’s need to replenish fluids.

Before death, the sustained rapid heartbeat caused by hypovolemic shock also leads to fluid accumulation in the sac around the heart and lungs. This accumulation of fluid in the membrane around the heart is known as pericardial effusion, and the fluid around the lungs is called pleural effusion. This clarifies why, after Jesus passed away and a Roman soldier pierced Jesus’ side with a spear, penetrating both the lungs and heart, blood and water flowed from His side just as John described in his Gospel “But one of the soldiers with a spear pierced his side, and forthwith came there out blood and water.”, (John 19:34).