...compressed disks at L4/L5? Just had this treatment, considering spinal fusion if this doesn't work. And how long does it take for the pain relief to kick in?

I have had several epidural steroid injections for L4/5. I takes from a day or so to a week to get the pain relief. The first one lasted 3 years but as my back got worse they lasted a shorter time. Finally, my spine was so bad I had a lumbar laminectomy and fusion. GOOD LUCK! I understand your pain!

after a week and no relief, I had the disk fusion, one of the best things I did to get rid of pain

It can provide pain relief for 6 months or longer, but sometimes it does take a few days for the steroid to kick in and go to work and occasionally up to a week. And sometimes, unfortunately, the injections don't work at all. Here's a good link for epidural steroid injections:http://www.professionalradiology.com...id%20injection