All of these meds have their place in the treatment of back pain. I have found NSAIDs to be very effective and with limited side effects. Muscle relaxers are also helpful for the treatment of spasms, but can make you tired. I typically limit my use to bedtime. Oral prednisone never did anything for me except maybe keep me awake, but others have benefited from their use. These are all pretty standard first line treatments.

Icy Hot patches or Biofreeze gel both work really well for pain relief from muscle spasms and have no side effects as long as you don't mind the smell of menthol.