What is the Best Way to Lighten Dark Scars?

I am guessing that since you are in the Philippines you may be of Asian extraction? If so, post inflammatory hyperpigmentation is a common problem and results from relatively minor injury with dark pigment as a consequence. Peels and bleaching agents may be of use, but in some patients may also result in dartkening. Treatment with certain lasers and light devices is usually successful but only in very the experienced hands of a physician acquainted with treating Asian skin.... more

It is difficult  to say what you need without seeing photos of the problem area. Are these scars from the collagen injections? or the injection sites themselves?