Acne Scars, PIE + PIH
One of the top questions I get is, "How can I fade acne scars?" This is a big question because "acne scars" can mean different things. While pimples are the start, your skin can respond in three main ways: true acne scars, post-inflammatory hyperpigmentation (PIH), and post-inflammatory erythema (PIE). Each type needs its own treatment, so knowing the difference is key to finding the right solution and seeing real results.
Acne Scarring
Acne scarring falls into two categories:
Atrophic Scarring - A loss of tissue or damage to the pore and follicle leaving a pitted or indented scar. There are a few different types - icepick, rolling, or boxcar scars which you can see in this image.
Hypertrophic Scarring - An overgrowth or excess of tissue leaving a raised scar and often called a keloid which you can see in the bottle right image.
Post-inflammatory Hyperpigmentation (PIH)
PIH is the overproduction of melanin in the skin triggered by the skin’s natural response to inflammation. If you don’t know what melanin is, it’s the protein that gives the skin, hair, and eyes color. It also causes freckles, birthmarks, and what is commonly referred to as age spots. (We produce more melanin as we age, so these “age spots” pop up.)
Common causes are acne, a cut, cold sores, a rash, or sunburn. PIH is made worse by sun exposure, so the theory that “the sun treats acne” is actually a terrible idea unless you want some lovely PIH!
PIH is usually flat and is darker than the surrounding skin. Discoloration can range from light to deep brown or even black.
Post-inflammatory Erythema (PIE)
PIE is damaged or dilated capillaries (blood vessels) caused by inflammation and trauma.
Over-exfoliation, sunburns, and inflamed acne are all causes. Dryness and dehydration will also contribute which is unfortunate since many acne treatments are often drying. Squeezing and picking pimples will contribute to inflammation and trauma. Have you ever attacked a pimple with your fingernails? That absolutely can break blood vessels, so no picking! PIE can vary from pink and red to deep purple.
How can I tell the difference between acne scarring, PIH + PIE?
If you have atrophic or hypertrophic acne scarring it’s pretty apparent, however, it can be hard to spot the differences between PIH and PIE, and often a person will have a combination of both. In the treatment room, I’ve always performed what I like to refer to as the “press test” during a skin analysis. This is simply applying light pressure to the skin where the suspected PIE or PIH is to see if the skin turns white. This is known as skin blanching, which is the temporary restriction of blood vessels.
Another test that is basically the same concept but uses a clear glass against your face so you can see through it. PIH will be unaffected while PIE will turn white. It may not be 100%, but it’s a helpful guide.
Here is a SUPER up-close photo of my face. I had a few PMS pimples about three weeks ago (it has faded a bit already) and you can see the difference between the pink PIE and the brown PIH which I have circled. When I press on the PIE area it disappears for a few seconds confirming to me that it’s PIE.
A Quick Recap
Acne Scarring = damage, loss/overgrowth of tissue to the follicle resulting in an indentation or raised scar.
Post Inflammatory Hyperpigmentation (PIH) = ranges of brown to black spots that are melanin.
Post Inflammatory Erythema (PIE) = ranges of pink to red spots that are dilated blood vessels.
Treatments + Prevention
Now that we know the differences and causes, I am sure you are wondering how to treat each of these types of marks. While both PIH and PIE can fade on their own, it can take months, depending on the severity. It may also never go away, like my PIH, which has been there for years.
Acne scarring is a bit trickier since there is actual damage to the pore/follicle, but there is hope!
Treatment of Atrophic + Hypertrophic Scarring
It really depends on the type of scar and the severity. In my opinion, the most effective options require medical help from a dermatologist. Also, NO PICKING!
Cosmetic fillers - Hyaluronic acid cosmetic fillers like Restylane will help to plump out the indentation.
Subcision—This is a minor surgical treatment in which, after some local numbing, a needle is inserted under the skin and moved back and forth to break up scar tissue. It is ideal for rolling or boxcar acne scarring.
Fractional Carbon Dioxide Laser (CO2) - This laser treatment creates microscopic holes in the deeper layers of the skin, stimulating collagen production and helping to smooth out acne scarring.
Professional Strength Peels—Medium to deep-depth TCA peels help to reduce the appearance of scars by making them go from deep to shallow.
Professional Depth Microneedling - I say professional depth because I realize you can pick up an inexpensive derma roller on Amazon for a DIY. It’s not the same. The needle depth required to effectively, safely, and hygienically treat an acne scar will require topical numbing, and the skin will bleed. I DO NOT recommend doing this yourself at home.
Cortisone injections or a laser resurfacing treatment - This is the best treatment for keloid scarring.
Treatment + Prevention of PIH
The best methods are inhibiting melanin production and reducing the amount of sun exposure you receive.
SUNSCREEN, HATS, and SHADE. Not only is it preventative, but it’s also the treatment! Ya, dig?
Speeding Cellular Turnover - The faster your skin’s cellular turnover is, the faster you can eliminate PIH. Products with these ingredients:
Alpha hydroxy acid (specifically glycolic and lactic acid) - I love this 10% glycolic acid serum from Naturium.
Non-prescription retinol and prescription retinoids like tretinoin
Melanin inhibitor products
Tranexamic acid inhibits melanin production, is known for its calming abilities, and helps restore the skin barrier—all of which are important when trying to treat PIH. My favorite product containing tranexamic acid and other brightening and melanin-inhibiting ingredients is Alastin A-luminate Brightening Serum.
Lightening products/ingredients:
Bayberry
Aloe vera
Mushroom extract
Licorice root
Vitamin C
Bearberry or the synthetic version of alpha arbutin
Kojic acids
Fermented rice
Azelaic acid
Niacinamide aka vitamin B3
Soy
Hydroquinone—I will mention this commonly prescribed skin bleach, but the jury is still out on whether it’s a potentially harmful long-term ingredient.
Professional Strength Peels - See an esthetician for a monthly series of peels, particularly glycolic acid.
Microdermabrasion - Effective for PIH, but I would not recommend this for someone with a combination of both PIE and PIH.
Laser Treatments - These are great because you will see results quickly. Intense pulse light (IPL) or Broad Band Laser (BBL) are good options, but I would recommend seeing a dermatologist to receive proper recommendations.
Treatment + Prevention of PIE
Time - Not what you want to hear, but it’s true; time (and patience) will help fade PIE even with no treatment.
Vitamin C - A less commonly talked-about benefit of vitamin C serums is that they strengthen the capillary walls. Since PIE is dilated blood vessels, this helps to reduce the redness.
Vascular Lasers - This laser treatment works by dissipating the pooled blood vessels.
Being Gentle - Harsh scrubs/ingredients, picking and squeezing pimples, and sun exposure can worsen PIE. Be gentle!
A final thought
Did I mention not picking up and wearing sunscreen? LOL.
