Tailbone standing without pain sitting up pain may be caused by tailbone fracture, disc herniation, sacroiliitis and other reasons. 1. Tailbone fracture: Violence, fall, high fall, etc. can lead to contusion or fracture of the tailbone, which can cause no pain when standing and pain when sitting down. 2. Herniated disc: Herniated disc can lead to spinal cord and nerve root compression, which can cause lumbar pain, sciatica, lower limb pain and other symptoms, and because the nerve is squeezed when sitting, which shows the symptom of pain when sitting up without standing. 3.. Sacroiliac arthritis: sacroiliac arthritis is a kind of non-specific aseptic inflammation that occurs in the sacroiliac joint area. Clinically, it will be manifested as lumbosacral pain, joint contracture, morning stiffness and dysfunction, etc. It will also appear that the tailbone has pain when sitting up without standing up. When there is pain in the coccyx, it is recommended to go to the hospital in time to clarify the cause and receive professional treatment from the doctor.