Purpura Purpura or bruising, commonly seen with pulsed dye laser therapy. sign of effective energy of 595nm, 585nm pulsed dye laser. Inform patients that purpura is a temporary phenomenon that usually lasts about 1 week. Newer devices for vascular therapy with larger pulse widths have effective energies that do not cause purpura formation. Hyperpigmentation Hyperpigmentation may occur after any laser or intense pulsed light treatment. Most hyperpigmentation is self-limiting over time. Excessive hyperpigmentation is most commonly seen with exfoliative laser treatments, especially carbon dioxide lasers. Duration averages 3-4 months and is seen mainly in patients with darker skin tones and after sunburn. Some pigmented lesions have significant hyperpigmentation after laser treatment, such as melasma. Hypopigmentation Hypopigmentation is usually temporary, and laser treatments using melanin as the target color base are more common, especially for tattoo removal treatments, hyperpigmented skin lesions, and laser hair removal, and is especially noticeable in people with darker skin tones, and after scar treatments. Blisters and scabs Blisters are caused by laser heat damage to the epidermis, such as excessive laser flow, after sun exposure to the skin to the laser excess and collection. Scabbing is common in Q-modulated laser treatments, especially tattoo removal treatments. Crusting is an expected complication of laser treatments using high flow short and long pulse width lasers. Scarring Scarring is a complication of laser treatment, either directly due to laser heat damage or secondary to infection. Atrophic hypertrophic scarring is caused by excessive collagen damage in the dermis. With exfoliative laser treatments, there is a greater risk of scarring if carbon dioxide or poor selection is used. The number of treatments per session and energy level are important factors in scar formation. Scarring can be minimized by the use of cooling devices.