I would think that taking any drug like this would probably have harsh effect on your kidneys.
And you would “think” wrongly. Not sure where you got this idea, but Vaniqa is a TOPICAL cream and shouldn’t have any effect at all on internal organs. Eflornithine is only used orally or by injection for sleeping sickness; even then it doesn’t seem to effect the kidneys at all. Since Vaniqa is never taken orally, though, this isn’t a concern at all.