Paraphimosis is a painful swelling of the retracted foreskin of the penis.
What is going on in the body?
When the foreskin is retracted it usually slips back over the glans, or head of the penis, if the penis is not erect. Sometimes the foreskin remains retracted, restricting the flow of blood out from the glans. This causes swelling, and the ring of tissue that keeps the foreskin from slipping back over the glans tightens even more. If the foreskin is left in a retracted position long enough, the painful swelling known as paraphimosis can result.