Photodynamic therapy is non-curative and aims to control the lesions and delay the development of the disease, which requires several times of zoning treatment. Generally need to interval of 2-3 months; 3, appear local or whole body pigmentation, must reduce sun exposure or apply sunscreen as appropriate to reduce pigmentation of exposed areas. 4.Eat fresh vegetables or fruits rich in vitamin C, E, carotene and fiber, and protein-rich food to promote the excretion of photosensitizers from the body; 5.To avoid or reduce infection and scar formation, local antibiotic ointment (Bactroban, etc.), Xifaxin or Bevacor cream can be applied appropriately; 6.After treatment, edema, exudation, crusting, etc., need to strengthen care to prevent scar formation; 7.Redness, swelling, pain and itchiness may occur. 7. Allergic reactions such as redness, swelling, itching, blistering, etc. should be strengthened by strict light avoidance measures, and oral hormone (prednisone) or anti-allergic drugs (paracetamol, centrum) can be taken to prevent scar formation.