Had Levulan treatment for pre-cancers. How soon can I try it again?

Impossible for us to comment without photos. Some areas of solar damage maybe concentrated in areas, whilst skip areas can occur. PDT then activates the ALA or the active chemical that was placed in the treated area. Bottom line, we do not know the clinical indication, nor the lesion or field ...

Most severe reactions are because of one of two things: There was too much UV exposure after the light OR the sun damage on your face is very severe. I think that this is a great option for you but you may be better off at first with either a shorter incubation time or less...

PDT causes oxidation and this results in inflammation of the skin and controlled cell death, this means that skin peeling is commonly seen. This will settle in a few days. All the best, Dr Davin Lim. Brisbane. Australia.

Your dermatologist will advice you - depending on the location. If its facial PDT, 48-72 plus hours, if its on the leg, one week. Really depends. Be guided by your dermatologist. All the best, Dr Davin Lim. Brisbane. Australia.

PDT is a good option for patients who have acne who want to try an alternative treatment course but its not particularly great at getting rid of blackheads. Blackheads usually require physical extraction and a cream program to prevent them from happening in the first place. 

This is a common question.  Most individuals note some degree of redness, tingling or peeling during or after the procedure.  However, different patients metabolize medications at different rates.  The persistence of your dry patch is definitely something your dermatologist wants...