My doctor put me on statins some years ago after having a blood test which revealed high cholesterol. I had no noticable side effects so after 3 months I had another blood test to check how the cholesterol was going. Liver enzymes were almost off the scale with my GP saying that she was surprised I wasn't bright yellow!
We argued about the cause with me saying it must be the statins as I was OK 3 months ago before I started taking them - she disagreed so I stopped taking them and changed doctor. Another blood test and a liver scan 3 months later - back to normal.