Pretreatment of skin prior to nonablative or ablative laser resurfacing is common practice, particularly in darker skin types. Treatment regimens include using hydroquinone 4% (and other hydroquinone-containing combinations) once to twice daily for 1-2 weeks prior to the laser procedure. The rationale makes sense. Quieting melanin production by inhibiting tyrosinase would seem to decrease the incidence of postinflammatory hyperpigmentation after laser resurfacing procedures. But is this common practice effective?
For ablative CO2 resurfacing in 100 patients Fitzpatrick Skin Types (FST) I-III, there was no significant difference in the incidence of hyperpigmentation in those randomized to be pretreated with either hydroquinone, glycolic acid, tretinoin, or to no treatment.1 The thought was that the follicular melanocytes involved in re-epithelialization were not affected by the pretreatment. This is the only published laser resurfacing today to date examining various pretreatment protocols with hyperpigmentation as a primary study outcome. From this study, it seems as though pretreatment before laser resurfacing is not helpful, but what about for nonablative resurfacing in darker skin types (FST IV-VI)?
In darker skin types (FST IV-VI), the risk of postinflammatory hyperpigmentation (PIH) is inherently higher and the incidence after laser resurfacing is greater. While the incidence of PIH is lower with nonablative fractional resurfacing, compared with ablative resurfacing, PIH can still occur whether pretreatment hydroquinone is used or not.2,3,4 To date, there are no published studies looking at the incidence of PIH when comparing pretreatment antipigment agents versus no pretreatment for laser resurfacing for acne scars in darker skin types. A split-face study comparing pretreatment on one side and no pretreatment on the other could help delineate whether this practice is evidence based.
For nonablative fractional laser resurfacing of acne scars, lower densities in darker skin types are recommended and may help reduce PIH risk. There is no statistically significant difference in improvement of acne scars in using low versus high densities using the same fluences. However, some studies note that higher densities clinically resulted in a mild improvement of acne scars over lower densities (not statistically significant); thus, if lower densities are used, it is possible that more treatments may be needed.4,5
Vigorous sun protection before and after treatment is prudent, with sun avoidance and physical sunscreens reducing the risk of PIH in darker skin from irritant or allergic contact dermatitis, compared with chemical sunscreens. If PIH occurs, it is often self limited (up to 1-2 months). Sun protection and posttreatment regimens of hydroquinone (or other lightening agent) aid in hastening improvement.
If the patient is undergoing nonablative laser resurfacing to treat pigmentation, such as melasma, then hydroquinone pre- and postlaser is appropriate. In my opinion, laser treatment of melasma should not be first line because of safety and efficacy concerns. However, in these cases, hydroquinone prior to laser has shown benefit.6 In addition, hydroquinone after nonablative fractional resurfacing may enhance penetration of the topical and improve efficacy.
In summary, the evidence shows that pretreatment with antipigment agents is not warranted in skin types I-III for ablative laser resurfacing. Pretreatment with antipigment agents for nonablative laser resurfacing for melasma (which should not be considered a first line treatment for melasma) is warranted. However, at this time, it is not clear whether pretreatment with antipigments for nonablative laser resurfacing for acne scars in darker skin types is useful. Lower densities should be used and if PIH does occur, it is usually self limited, and posttreatment hydroquinone or other antipigment agents may be useful.
Dr. Wesley and Dr. Talakoub are co-contributors to the monthly Aesthetic Dermatology column. Dr. Talakoub is in private practice in McLean, Va. Dr. Wesley practices dermatology in Beverly Hills, Calif. This month’s column is by Dr. Wesley.