Why do pimples leave dark marks after they heal?

Doctor's Answers (3)

Inflammation is certainly a big factor for the PIH. At the same time, you may be wondering why some of your friends do not get the PIH despite having similar acne. There are various other factors to consider as well. 

Genetics is another factor. Some of us simply get more scarring and PIH with acne. This is especially true among those with coloured skin. Coloured skin is more responsive to insult, and produces more melanin (which results in pigmentation). 

Our lifestyle may also influence our skin response. Frequent exposure to sun results in more  "reactive" skin. How we apply sun protection and moisturiser may affect the outcome of acne as well. Poor skincare regime would certainly worsen the outcome.

Now that you know that there are factors that you cannot control, do not be disheartened as there are many factors that you CAN control, such as sun avoidance, sun protection and proper skincare. You may also use medications and undergo some light therapy to treat the active acne.

There are also medications to reduce the number of comedones to further reduce acne outbreaks. By taking active steps to clear up the inflamed acne, you will reduce the severity of the inflammation and hence lower the PIH and scarring. There is still hope!  

Post Inflammatory Hyperpigmentation (PIH) does not always occur. It is a result of increased blood flow to the affected area, resulting in a stimulation of the cells that produce pigment.

PIH is more likely to occur in darker individuals. It does not incur for all injuries. If your acne was particularly large and swollen or if you were exposed to a lot of sunlight during this period, it is possible that an overstimulation of your pigment cells may have occured, resulting in PIH. Squeezing it will result in increased blood flow and not only worsen your acne, but will leave you with an increased chance of developing PIH.

When left alone, PIH can fade over time. It may take sometimes up to 6 months or it may never actually fade completely. The process of clearance can be speeded up using either a Q-swtiched Nd-YAG laser or a Picosecond laser to help break up the pigment and allow for the body to clear it out faster. I prefer the latter. You can also use creams that contain hydroquinone and retinol combined in order to suppress pigment formation and push the current ones closer to the skin surface for it to eventually flake off.

Thank you for your question.

Post inflammatory hyperpigmentation (PIH) occurs after an inflammatory event, leading to an increase in melanin production in the affected skin area. The more inflamed an acne breakout, the larger and darker the PIH. 

That would explain why even if you did not pop the pimple, PIH can still occur as acne is an inflammatory event, which may still eventually lead to PIH. 

Hope that answer your question and have a wonderful weekend. Do let me you if you have any further questions.

Best Wishes,


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