How often does a bulging disc progress to herniation?

No often: Once diagnosed, if treated properly, the symptoms, of a buldging disc will settle down. Over time the disc may shrink back towards normal. Barring a new incident is should not herniate.

Varies: It varies somewhat. The development of a degenerative or bulging disc is very common and is present in 30 percent of those over 35, and 90 percent over 60. The incidence of a symptomatic disc herniation causing symptoms requiring treatment is thankfully much less common. Thank you.