Compared to certain other plants, peace lilies don't need to be pruned very frequently. However, if, for whatever reason, one or more of your lily's limbs or leaves become brown or wilted, you may want to prune the leaves to keep the plant from wasting energy on the dying appendage.
Accutane is a retinoid, and not related to anti-biotics so the side effects are different. However, the list of potential rare side effects of accutane is long and includes headaches, nausea, muscle pain and depression.
Consider other forms of treatment. If your acne is persistent, but not severe, then you may want to consider a different form of treatment. Accutane is not used for mild to moderate acne because of the risk and range of its side effects.