Is the skin cream Mederma effective for treating acne scars? And does it have any adverse side effects?

Is there anything like people with a particular skin type or who are already undergoing medication cannot use mederma? Or--do you need a prescription to buy it?Is the skin cream Mederma effective for treating acne scars? And does it have any adverse side effects?
I don't know about Mederma, but there is two things I use to eliminate scarring. First, I use vitamine E oil, which keeps fresh scars from hardening up. If the scars are external, get the 1000 IU capsules and break one open and apply it to the scar every day for a week, every week for a month. Then, to totaly erase most scars I use arnica oil. Usually this comes in a dilute form (mixed with olive oil). This form is, in my opinion, too weak to be worth the cost. I get the arnica absolute from the essential oil company online. I use a toothpick to dip into the bottle and rub onto the scar. It takes time, but is quite effective. And, you don't need a prescription. A one dram bottle, while small, will last you six months to a year. I've totally eliminated scarring from my gall bladder operation over a 1 1/2 year period.