If you experience stiffness in your lower back in the morning or severe lower back pain when standing up after sitting for a long time, it may not be a common herniated disc. It could be ankylosing spondylitis, an autoimmune disease.

Ankylosing spondylitis is a type of autoimmune disease where immune cells, which normally protect the body from harmful substances, mistakenly attack the joints of the spine, leading to chronic inflammation. Over time, this inflammation can cause the joints to fuse together, resulting in stiffness and deformity.

Ankylosing spondylitis is not uncommon among those in their 20s and 30s. According to statistics from the Health Insurance Review and Assessment Service, approximately 115,000 patients received treatment for ankylosing spondylitis in 2023, with those aged 20–39 accounting for about 45 percent of the total. By gender, males accounted for about 70 percent, significantly more than females.

Ankylosing spondylitis primarily causes inflammation in the lumbar spine and sacroiliac joints. Over time, the ligaments connecting the vertebrae ossify, leading to spinal stiffness. As the condition progresses, treatment becomes more challenging, making early diagnosis and treatment crucial. The problem is that ankylosing spondylitis is often misdiagnosed as other conditions, such as herniated discs.

“Ankylosing spondylitis often goes undiagnosed because its initial symptoms are similar to those of a herniated disc,” said Professor Lee Sang-heon of the Department of Rheumatology at Konkuk University Medical Center. “However, unlike a typical disc herniation, if pain may actually improve after exercise or physical activity, or morning stiffness lasting more than 30 minutes upon waking, you’d better suspect ankylosing spondylitis.”

While a herniated disc is a structural issue caused by external injury or degenerative changes leading to disc protrusion and nerve compression, ankylosing spondylitis is characterized by inflammation at the ends of ligaments attached to bones, resulting from the excessive secretion of inflammatory substances triggered by an immune system response.

The two conditions also present different symptoms. While a herniated disc causes severe pain when moving and improves with rest, ankylosing spondylitis is characterized by reduced pain after activity. “Ankylosing spondylitis tends to improve with appropriate exercise,” Professor Lee noted. “However, symptoms may worsen if one remains lying down for an extended period.”

Ankylosing spondylitis goes beyond simple lower back pain and can affect the entire body, including uveitis and heart disease, so early detection and personalized immunotherapy are necessary, along with a multidisciplinary approach. This disease is characterized by strong genetic factors, so if there is a family history of ankylosing spondylitis, it is important not to overlook lower back pain and seek professional medical advice.

While ankylosing spondylitis is difficult to cure, early detection can help slow disease progression and reduce daily discomfort by suppressing inflammation. “Early visit to a rheumatologist allows for rapid diagnosis through detailed examination, blood tests, X-rays, and MRI, and treatment can not only slow progression but also lead to a cure in some cases,” Lee emphasized. “However, delayed diagnosis may result in irreversible damage, including spinal stiffness.”

Treatment for ankylosing spondylitis includes nonsteroidal anti-inflammatory drugs (NSAIDs), immunosuppressants, and biologic targeted therapies, with medications adjusted based on symptoms for long-term management. If symptoms, including morning stiffness, hip and lower back pain, or pain that improves after activity, persist for more than three months, they should not be dismissed as simple muscle pain; specialized medical care should be sought.

In addition to medication, regular stretching and joint exercises can help alleviate pain. In particular, it is recommended to perform light exercises daily in the morning to maintain spinal flexibility and mobility. Smoking cessation is essential, and avoiding excessive weight gain, maintaining adequate sleep, and managing stress are also important in preventing disease progression.

“If you spend long hours sitting at work or driving, it is advisable to take short breaks of about five minutes and incorporate light stretching exercises in between,” Lee said. “Since this condition is a chronic inflammatory disease caused by immune system dysfunction rather than mechanical damage, targeted immunotherapy is often more effective than surgery. Therefore, consulting a rheumatologist for diagnosis and treatment is recommended.”