The biggest danger is muscle weakness which if to severe can lead to a condition call Rhabdomyolysis. This usually happens if you are taking other medications and it interferes with your ability to metabolize the statin in Pravachol. This can also occur if you have any problems. If you have severe muscle weakness and brown or dark urine you need to see a doctor imediately. As it can cause liver problems, a sign of liver problems is yellow patches of skin or yellow in the whites of your eyes. I hope this helps.