How do I prepare the skin for fraxel for PIH?

In my practice, I try to stay away from these combination regimens, as cortisones are non-selective inhibitors of melanocytes.  I would recommend my patients to start Melarase AM and Melarase PM for the pigmentation.
I would start with an intense skin rejuvenation protocol for age spots that includes fractional laser, Covalent chemical peels, and daily skin brightening creams to improve your skin’s complexion. Laser therapy, he adds, must be combined with a proper skin regimen to enhance and maintain youthful results.
He recommends the following skincare products for dark age spots: Melarase
MelaClenz Brightening CleanserMelarase AM: Day-time skin lightener with SPF 30Melarase PM: Night-time skin lightenerMelapads: Daily Exfoliating PadsReplenish Retinoid Cream: Exfoliating and skin-stimulating night creamBest, 
Dr. Karamanoukian
Realself100 Surgeon

Thank you for your question. I find Fraxel a poor choice for pigment issues, and in many cases it can make things worse. Try other options first. I would try a V-Beam or a Q-switched laser first. Consider eLure bleaching, Kojic Acid etc. instead of HQ. I hope this helps!

An in ofice consultation is the only way to assess the degree of PIH and the best treatment.  However, it does not sound from your decription that Fraxel would be the best choice for you.  The eMatrix may be a better choice for you. Please consult a board certified dermatolgist with expertise in comsetic procedures.  Best, Dr. Green