I have both robaxin and zanaflex (tizanidine).one was for bladder spasm other for muscle pain. which would be better for knotted muscles & soreness in abs/ribs.

Here are some...: Both drugs share similar mechanism and indication to ease musculoskeletal pain as well as have similar profile of side effects. Before succumbing to their long-term use, ask the treating doctor about why you have had the pain - if physically related or of unknown cause? Based on such, formulate a long-term plan of caring your pain. And behavioral modification & physical therapy are the first line.