Using a Side Effect to Therapeutic Advantage: The Darkening of Red Eyebrow Tattoo Pigment Following Q‐Switched Laser Treatment

Background. Q‐switched lasers are commonly used to achieve tattoo removal, utilizing the principle of selective photothermolysis. However, certain tattoo pigments may darken following laser pulsing. Objective. To determine whether this side effect can be used to therapeutic advantage in a woman who previously had her eyebrows enhanced with a dark tattoo that spontaneously changed to a reddish hue over time. Method. The woman's eyebrows were pulsed with the Q‐switched Nd:YAG laser at both 532 nm and 1064 nm. Results. The test areas pulsed with the 1064 nm laser revealed partial clearing. However, 532 nm Q‐switched Nd:YAG pulses produced darkening of tattoo pigment both at the test sites and in the subsequent treatment. Conclusion. Q‐switched lasers can produce darkening of red tattoo pigment. In some cases this side effect can be used to therapeutic advantage.