There is no medication that has no side effects.
But in recommended doses, you can avoid any. So as with Duromine.
As far as I know, many trials have been conducted with Duromine, yet none of them revealed side effects on the liver.
Just a few numbers: 30% of the active substance is metabolized in liver, the rest 70% in kidneys, excreted with urine.
So, I belive Duromine can only affect the liver functions when you take some other medications with it.
And if you want to use Duromine with other drugs, read drug interactions first.