Some people notice darker skin after surgery or an office treatment. This is called post-inflammatory hyperpigmentation (PIH). It is more common in darker skins but it can occur in anyone.
PIH is caused by the skin over-reacting to mild injury with a sun protective response. The skin has cells called melanocytes that make melanin which gives skin its color. All skin irritation including surgery and injections may cause mild, temporary inflammation. In some skins, this inflammation activates melanocytes which rapidly darken the skin. Once activated, the cells may keep the skin too dark for months, or permanently.
It is hard to predict if you will get post-inflammatory pigmentation. Two things usually seen in patient’s that develop PIH are a surgical scar which is white or a natural color or has skin that burns or at most gets a very light tan. If you get burned or cut and your skin appears darker after you have healed, this is usually PIH.
The best way to prevent post-inflammatory hyperpigmentation is use a physical sunblock containing zinc oxide and titanium dioxide every morning applied to the affected area. If you know you get PIH and you having a procedure or treatment, you can apply 4% hydroquinone to the area being treated twice a day for 6 weeks prior to your procedure and 6 weeks after. Also applying tretinoin 0.1% (Retin-A) cream to the area once a day for the same time period can help. Both of these creams must be obtained by prescription.
If it is too late and you already have post-inflammatory hyperpigmentation start the hydroquinone and tretinoin treatment as soon as possible. If is an old scar or injury applying 10 % shea or cocoa butter twice a day for one year can be effective.