Mederma does next to nothing. You can try castor oil as well and comfrey for "healing" effects. If you have young scars (less than a year) you would be better served with silicone liquid or patches, this is the same thing they have you do after surgery.

It all depends on the type of scars. For keloids silicone works well or some depressed (pits) young scars.

You don't want to trap the BP with something else. So do one at night, and one spot treat during the day.