For how long does it usually take for an epidural steroid injection to alleviate a herniated disk to take effect?

3-4 days: Initially it can take 3-4 days for the steroid to provide relief but that effect may take up to 10-14 days in some people. It is not uncommon to hear patient say it took two weeks to get relief.

Tricky: An epidural steroid injection may provide immediate relief just after the procedure if a numbing medication is mixed with the steroid; this will wear off in 3-4 hours typically. The steroid takes 2-4 days to kick in, but some people don't notice it for over a week. You may get partial relief or it may be excellent, but come right back and another epidural may be needed.