The severe back pain a few days after the lumbar puncture may be caused by the puncture itself, such as local subcutaneous bleeding, local aseptic inflammation, infection at the puncture site and other causes, or it may be caused by the lumbar region’s own diseases. 1. Local subcutaneous bleeding: when the patient’s lumbar spinal space is narrow or the patient can’t do the lumbar puncture position, the lumbar vertebrae can’t be fully exposed, which makes the puncture difficult and leads to local subcutaneous bleeding and swelling, thus causing the lumbar pain. 2. Local aseptic inflammation: lumbar puncture has to pass through the interspinous ligament and supraspinous ligament to enter the vertebral canal, so repeated puncture may damage the interspinous ligament or supraspinous ligament and lead to the emergence of aseptic inflammation, which may cause lumbar pain, and the pain is more pronounced when bending and flexing. 3. Infection at the puncture site: Failure to protect the wound in time after lumbar puncture or strict adherence to the principle of asepsis may cause infection at the puncture site, resulting in symptoms of redness, swelling, heat and pain. Lumbar pain after lumbar puncture may also be caused by the transient aggravation of the lumbar spine’s own disease, it is recommended that the patient go to the hospital to clarify the specific cause of the lumbar pain, and timely treatment under the guidance of the doctor.