Picosecond lasers are more efficient in removing spots due to their narrower pulse width and higher pigment blasting ability. Of course, it also has disadvantages or adverse reactions. Specifically as follows: 1, picosecond laser causes swelling in the treatment area, this is because picosecond belongs to a kind of laser, and its rapid reach to the skin will cause skin irritation and swelling, and such swelling will basically return to normal in about 1 week after the treatment; 2, after the picosecond laser treatment, the skin will be dry, taut, and even flaking phenomenon, which is mainly because the picosecond laser will precipitate the melanin inside the skin into powder, which is mainly because the picosecond laser will be the most effective way to remove the spots. The principle is mainly because the picosecond laser will hit the melanin in the skin into powder, the skin is activated, the speed of cell division is accelerated, and the newborn cells of the skin are formed in large quantities, at this time, the skin needs more water and nutrients, if it is after the picosecond laser treatment, there is no immediate skin moisturizing and replenishment, there will be skin dryness, tautness, and even dandruff; 3, if it is the frequency of the operation as well as the parameters used are not proper, which will lead to certain color spots 3, if the frequency of operation and the parameters used are not appropriate, it will lead to certain pigmentation, reactive color deposition, such as chloasma, which will be more serious if it is not treated properly; 4, if poor measures are taken to take care of the skin after the treatment, such as going to the beach after the treatment for sunbathing, it will lead to local color deposition. All in all, picosecond treatment is very safe.