my wife has tried wartner gel pen for application to two warts one on neck and one on face but didn't know it was very powerful, some has spread to the surrounding area of skin and caused brown discoloration. not sure of the conc of the acid (TCA) but worried about damage to her skin. i am concerned they are selling such potent acid freely. can she put some baking soda solution on it temporarily or hydrocortisone cream? will the skin recover as she has only put a small single amount? thx