You will need monitoring, but the risk is almost nil. However, since being diagnosed with fibromyalgia I have been taking arthrotec and paxil. Muscle and joint pain are already being experienced, before taking zocor. In view of the ongoing muscle pain, I'd check CPK values to ensure they don't elevate with zocor. Specifically, male breast enlargement with associated pain and increased nerve sensitivity.
Breast enlargement is one of the potential risks.
Initially, I was a disbeliever, but I've seen it enough now to understand that it is real. Why it hits some and not others is unclear. You might try other lipid lowering agents like Pravachol. I've had some luck with this. While taking the drug I suffered general debility on a number of occasions and definite mood swings.