Post acne erythema are also called post acne erythema or macular erythema.
They are persistent pink to red marks that occurs in acne patients during the course of acne treatment and persists for sometime even after the acne subsides.
They are more commonly seen in patients with lighter skin (FST I-III), but PIE can also be seen in Indian skin type FST III & IV as well.
PIE is a relatively new term, which is different from post inflammatory hyperpigmentation (PIH) i.e the brownish black scars that follows an acne eruption.

How and why does PIE occurs?
- Still not clearly understood. Potential explanation is that during the process of inflammation, some pro-inflammatory cytokines that are released causes dilatation of the small blood vessels present in the superficial most part of the dermis.
- The epidermis while still being in the process of maturation, is thinner, more transparent and can thus more incident light is reflected from the underlying vasculature

How to manage PIE?
- So far, there is not much options for treating PIE.
- The best approach is to minimise the risk of developing PIE in the first place.
- As blood vessels will dilate during the process of healing, so some amount of erythema (redness) is expected. However as persistent inflammation is the driving force for long lasting erythema seen as PIE, addressing the factors that causes the inflammation will help minimise the chances of developing persisting PIE.

You do not need to buy products with these individual ingredients separately. Just look for products formulated with these ingredients together either in your moisturiser or sunscreen
Treatment that have been tried for PIE
For most individuals with acne, PIE subsides spontaneously after a few weeks to months just with gentle, supportive care in the form of sunscreens, moisturisers +/- ingredient to help with the inflammation.
However for some, PIE can be persistent even with the above measures. Medical management that have been tried include topical creams and different types of LASERS.

There is still no standard treatment for PIE and large scale studies are still lacking
So far, LASER treatment is still the best option for persistent PIE