Post-inflammatory hyperpigmentation (PIH)
Injury prompts melanocytes to over-produce pigment, leaving a brown patch that can take months to fade. Risk rises with phototype, with aggressive/over-worked technique, with sun exposure during healing, and with any healing infection or cold sore. It usually resolves, but slowly, and can be helped by sun avoidance and, if needed, a dermatologist.
Reducing the risk
Fewer, lighter passes; longer intervals between sessions for reactive skin; scrupulous sun protection through healing; treating any infection or HSV promptly; and pushing the touch-up out to 8–12 weeks so PIH has resolved before more trauma.
Scarring
True keloid or hypertrophic scars from cosmetic lip tattooing are uncommon because the work is shallow, but clients with a personal or family keloid history, or who picked scabs, are higher risk. Screen for it; if present, many artists decline lip work or do a cautious test area first.
