The main study for Simvastatin was the 4S trial which proved that the incidence rate for side effects at 40 mg of Simvastatin was 1
in 2,220 prescriptions. What is interesting is that the incidence rate
in the placebo group was 1
in 2,223. Also muscle pain is a very common complaint and is a symptom of many conditions.
Ed is correct about the half life, a normal 40 mg dose is out of your system within a day. Also, any side effects are usually gone in a couple days or a week at most.