What is the Percentage Glycolic Acid That Should Be Used on Minors?

My friend's daughter went for an underarm bleach in one derma clinic but was prevailed upon by the nurse attendant to undergo a glycolic peel instead. She is only 15 years old. A few minutes after, she felt pain and itchiness in her unerarms. She was told it was only normal. When they got home, the burned sensation worsened in that her daughter can hardly close her arms and from the looks of it, it was more of a first degree burn. The percentage of glycolic acid used was 25%.