Post inflammatory pigmentary changes can be both light or dark in color. Post inflammatory hypo-pigmentation tends to occur in lighter skinned individuals whereas post inflammatory hyper-pigmentation tends to occur in darker skinned individuals.
Any type of skin injury can leave marks… sometimes, it’s the mark that bothers people more than the injury itself. For example, you have an acne pimple, that can go away in 5 days, but then a red mark becomes a brown mark, which then lasts for months to years after. Some people think it’s a scar, but it’s not. Scars last forever, whereas post inflammatory hypo- or hyper-pigmentation does resolve eventually… but it’s resolution is based on the individual person and sometimes may require treatment.
Why does it happen?
The 2 main cells in the skin are keratinocytes and melanocytes. Melanocytes in the skin produce melanin which makes skin the color it is. When the skin is injured, melanocytes are also injured which causes them to either make more melanin or makes it harder for the melanocytes to spread the melanin to nearby skin cells causing the skin to look discolored. This process is stimulated by the release of certain prostainoids, cytokines, chemokines, and other inflammatory mediators (i.e. leukotrienes, interleukins, tumor necrosis factor, reactive oxygen species) during the inflammatory process.
Who does it happen to?
A study in 2002 evaluating acne in skin of color found that 65.3% of African Americans (=239), 42.7% of Hispanics (n=55), and 47.4% of Asians (n=19) patients develop acne-induced PIH. Generally, PIH is worse in darker skin individuals than lighter skin individuals.
What can be done?
PIH can worsen with UV radiation or with persistent inflammation so treatments should be first aimed at calming down whatever is causing the PIH in the first place and being good about strict sun protection (wearing protective clothing such as UPF clothing and wearing sunscreen; reapplying every 1-2 hours).
First line therapies include lightening agents such as hydroquinone, azelaic acid, kojic acid, arbutin, certain licorice extracts, retinol, mequinol, ascorbic acid, niacinamide, N-acetyl glucosamine, and soy can be used individually or in combination with compounded medications. Some of these agents can be purchased over the counter at lower percentages or prescription strength by a dermatologist.
If the topical agents are not helpful, chemical peels (glycolic acid, salicylic acid, tricholoacetic acid, Jessner’s solution) and laser therapies (blue light photodynamic therapy, fractional thermolysis, Nd:Yag laser) to target deeper melanin deposition in the dermis may be required. However, this should be done by a board-certified dermatologist as darker skinned individuals are already at risk for pigmentary changes with the risk of further skin injury and thus, more unwanted PIH.
I am a board certified dermatologist based in Los Angeles. I am a comprehensive dermatologist caring for families. I love seeing children and adults. My youngest patient was 0 days old and her oldest was 110 years old. I have had psoriasis since the age of 8 and considered an expert in psoriasis and psoriasis treatments. I have lectured locally and nationally and published numerous papers on other topics such as skin manifestations of eczema, hidradenitis suppurativa, systemic lupus erythematous, granuloma annulare, microbiome, skin cancers, and more. My expertise includes knowledge in managing complex skin diseases. I am experienced with surgical treatment of skin cancers, as well as non-surgical methods to treat skin cancer and precancerous lesions. I run a full medical, cosmetic, and surgical dermatology practice. I am experienced with the use of complex dermatologic therapy, including biologic therapy, immunosuppressive medications, and phototherapy. I also treats fine lines and wrinkles non-surgically with combinations of botox, fillers, chemical peels, lasers, and radiofrequency. I perform minor surgeries such as excisions for cysts, lipomas, basal cell skin cancer, squamous cell skin cancers, and early stage melanoma. I am physician expert for Kopa for Psoriasis, part of Happify. I have been featured on podcasts and quoted in numerous online and print publications. I am honored to be named “Top Doctor” in Los Angeles magazine. In my free time, I volunteer for community events such as skin cancer screenings and at the local free clinics. I also teach internal medicine and dermatology residents at several academic centers. I try to do yoga every day and every year, I run a half-marathon at the Golden Gate Bridge.