When red acne scars are treated with PDL, do the scars fade immediately, or continue to fade over the coming weeks?

The effects of a pulsed dye laser can vary somewhat from patient to patient. However, it would be unusual to see significant improvement immediately after your first treatment. I would give yourself four to six weeks after that session to see how much improvement you might achieve. Keep in mind it is not unusual to require more than one treatment session or even more than one type of treatment to completely eradicate acne scarring. Make sure the doctor you are working with is both board-certified and experienced in acne scar revision procedures to ensure an optimal outcome. 

Thanks for your question.  We usually see the scars and redness actually darken for awhile, and sometimes even look bruised, but that eventually fade and hopefully you will have excellent results. The pulsed dye laser is great for red scars and vascular lesions.  Ask your dermatologist who is treating what to expect right after, and they will review post-laser care.  Good luck!