Can epidural steroid injections for back pain cause bone deterioration?

Steroid. Too much steroid can cause osteoporosis no matter where it is placed. Oral, IV or epidural steroid may increase chance of osteoporosis. The amount of steroid used in epidural injection for a herniated disk is less than the amount of steroid consumed as a Medrol (methylprednisolone) dose pack taken orally to treat the same symptoms. Generally, though, we do not recommend more than 3 steroid injections in 6 months.
Bone thinning. Most unlikely. Bone thinning is more common with repeated doses of systemic steroids administered over a longer periods of time. Epidural steroids are typically administered in the epidural space as single doses every 6-9 months sometimes. So bone side effects are unlikely.
Yes, but rare. The biggest risk of the steroid with epidural steroid injections is getting a condition called avascular necrosis. This is a rare disorder that usually effects large joints such as the hip or knee and can lead to the need for replacement. It can occur even after one dose of steroid. It is prudent to limit your dosage of epidural steroids to no more than 3 times per year. Be aware of this risk.