How to Get Rid of Acne Scars Explained (7 Studies) | PIE vs. PIH

by | Last updated Apr 18, 2020 | 174 comments

Our skincare brand is live!

After five years of writing research articles on Simple Skincare Science, we have developed our own products based on the content written around this site. To place an order simply go to, or follow us on instagram for updates!  We hope you have a great day 🙂

Now that you’ve successfully cleared your acne, you may staring at some stupid pesky red or brown marks that your breakouts left behind. Those stubborn little critters is what we’ll be focusing on in this article.

PIE hyperpigmentation before and after

Note: product recommendations at the bottom of this post.

Let me start off by bringing you up to speed about the differences between Post Inflammatory Hyperpigmentation (PIH), and Post Inflammatory Eythema (PIE). If you’re unfamiliar with these terms, allow me to blow your mind away.

The pesky red spots on your face from old acne you’ve been trying to treat aren’t post inflammatory hyperpigmentation (PIH) marks, and the products you’re using to target them may be ineffective. Okay, what the hell am I talking about? Let me explain.

Differentiating Between Types of “Acne Scars.”

The term “acne scars” has sort of become an umbrella term to describe three very different things:

  1. Post Inflammatory Hyperpigmentation (PIH).
  2. Post Inflammatory Erythema (PIE).
  3. Atrophic scarring.

Let’s distinguish between each.

What is Post Inflammatory Hyperpigmetation (PIH)?

Post inflammatory hyperpigmentation (PIH) are brown or black marks caused by an overproduction of melanin. Think freckles, birthmarks, and sunspots.

If you don’t know what melanin is, it’s simply the pigment that gives color to human hair, skin, and eyes. The cells that produce this melanin are called melanocytes. And the process of melanin production is called melanogenesis.

Were all those terms confusing? Here they are again.

  • Melanin =  pigment that gives skin, hair, and eyes its color.
  • Melanocytes = cells that produce melanin.
  • Melanogenesis = the process of melanin being produced.

Darker skin types (IV-VI) are more susceptible to PIH because they have overactive melanocytes.

  • What causes PIH?

PIH is triggered by an inflammatory response that initiates melanin production. (1) Possible causes include: getting a pimple, aging, pregnancy (melasma), hormones, and sun exposure.

Melanin protects your skin from the sun by absorbing 50-75% of UV radiation. (2) Ever wonder why dark skinned people don’t burn as easily? It’s because they have more melanin to protect themselves. More melanin means less susceptibility to sunburn.

Why is this important? Because the sun causes your skin to produce more melanin in order to protect itself. Melanin is the driving factor behind hyperpigmentation issues. The less work we give to our melanocytes, the better our prospects are in treating PIH.

This is why sunscreen is so important! It works by absorbing UV radiation, so melanin doesn’t have to. In other words, it’s doing the heavy lifting so your melanocytes can take a break. As a result, less melanin is produced — therefore, less hyperpigmentation. Get it?

What is Post Inflammatory Erythema (PIE)?

Post Inflammatory Erythema (PIE) is a recently coined term gaining traction in the dermatological world referring to the red or purplish marks left behind from inflammation (usually acne). (3) I have a lot of experience with this personally. Here’s the photo posted above again, so you can get a visual.

PIE hyperpigmentation before and after 

Notice how the spots are red and not brown? That’s one of the main ways of distinguishing PIE from PIH. The redness you see is a result of “discrete erythematous macules.” Or more simply put, damage or dilation done to capillaries (small blood vessels) near the surface of the skin resulting in cute little red spots (sarcasm). This is how I really feel about PIE:

PIE falls on the lighter spectrum of skin tones, and is less likely to affect people of color. It’s possible to have a mix of both PIE and PIH. In fact, PIE can sometimes turn into PIH if left untreated. I suspect that most people have a combination of both.

Treatments geared towards treating PIH (brown spots) focus on inhibiting melanin production, which unfortunately does nothing for PIE because it’s not a melanin-induced problem.

  • What causes Post Inflammatory Erythema (PIE)?

PIE is the result of inflammation caused by trauma. This includes, but is not limited to — inflamed acne, picking at pimples, popping pimples, dry or dehydrated skin, chemical burns, over-exfoliation, cuts, scrapes, scratches, sunburn, sun exposure etc.

  • How to test for Post Inflammatory Erythema (PIE).

Post inflammatory erythema disappears temporarily when pressure is applied to the area. PIH does not. This is known as “skin blanching.” Here’s a visual of what that looks like.

To do this test on yourself, find a clear container like a cup of glass or something similar and press down against the area you might suspect is PIE. If the mark becomes white and disappears, that’s a good indication you have PIE and not PIH.

Hyperpigmentation (brown spots) are unaffected by this test. However, using this method isn’t always the most accurate and should be used more as a guideline than diagnosis.

Atrophic Scars.

Atrophic scars are the actual indentations left behind in the skin after acne or inflammation has occured. There are three different kinds: boxcar, icepick, and rolling. I also have a lot of experience with this too.

 acne scars before and after

The photo on the left shows what I’m talking about. That was my atrophic scarring at it’s worst. Shameless plug: subscribe to my newsletter by using the right sidebar to stay updated on a future post I’ll make all about getting rid of acne scars from home. For the purposes of this article, we won’t be discussing atrophic scarring any further.

The Takeaway.

  1. Post Inflammatory Hyperpigmentation (PIH) = brown or black marks caused my melanin.
  2. Post Inflammatory Erythema (PIE) = red marks caused by dilated blood vessels.
  3. Atrophic Scars = actual indentations in the skin caused by acne or inflammation.

How to Treat Post Inflammatory Erythema (PIE).

At this point in time there are only two viable methods of treating PIE (as far as the research is concerned): vascular lasers (e.g. v-beam) and perhaps silicone sheets (you can find these on amazon).

Remember how I said PIE is the result of damaged or engorged capillaries near the surface of the skin? That’s what makes vascular lasers such an incredibly effective treatment. They work by penetrating the skin deep enough to reach, break down, and disperse the damaged blood vessels that are causing PIE. (4)

The mechanisms behind silicone sheets are less understood but are known to increase the hydration of the stratum corneum (outer most layer of skin), protect from bacterial invasion, and maintain skin barrier integrity. (56)

This is completely anecdotal, and I have no scientific evidence to back this up but from my personal experience — products containing Vitamin C (either ascorbic acid or sodium ascorbyl phosphate) and Niacinamide help tremendously. For product recommendations that contain these ingredients, scroll down to the table included at the bottom of this post.

Vaseline (petroleum jelly) or Aquaphor also helped my PIE fade faster. My suspicion is that it works by creating a barrier itself (like silicone sheets) that induces a moist wound healing environment to expedite the PIE-fading process.

I have a very strong suspicion that post inflammatory erythema (PIE) is worsened by a damaged moisture barrier or acid mantle, so like I mentioned in my how to get rid of acne article, you need to be really focusing on the moisturizing aspect of your routine and reduce irritation whenever possible. When I began doing those two things I sh*t you not, my PIE went from a deep red to lighter pink tone within a couple weeks and overall ended up fading significantly faster.

I’ve also noticed that whenever I get a pimple now, the redness subsides within a couple weeks to a month, when before it use to take upwards of a year! So yeah, hydrate hydrate hydrate.

There’s a lot of ways to do this. For me, it meant double oil cleansing, adding a very basic hyaluronic acid toner (I like the Hada Labo HA lotion), sometimes skipping my morning cleanse altogether, and a hydrating essence/gel (my favorite is the Benton Snail Bee High Content Essence — has a SEXY ASS ingredient list). But find what works for you!

  • How much does a v-beam laser session cost?

It depends on your location and dermatologist. I’ve seen estimates as low as $150 all the way up to $500. If you decide to invest in vascular laser treatments, do your research first and compare prices. These things are expensive, so don’t allow yourself to get ripped off!

  • Is there anything else that will treat my PIE?

Patience and time, my friend. I know you don’t want to hear this, but the difference in the photos above took several months. I understand that not everyone has a budget to afford laser treatments (heck, me included), so most of us will have to play the waiting game.

Rest assured though, the pesky red marks will eventually go away on their own given you don’t do anything silly like pick at your face or forget to wear sunscreen. 🙂 A lovely reddit user (u/MissPicklesMeow) said it best:

“Patience is cheaper, but sometimes harder to come by.”

How to Treat Post Inflammatory Hyperpigmentation (PIH).

The idea behind treating PIH is twofold: inhibit tyrosinase (an enzyme that catalyzes the production of melanin), and increase cell turnover rate so the spots fade faster. (7) Oh, and use sunscreen! LOTS and LOTS of sunscreen!

As mentioned earlier, melanin production is the driving force behind post inflammatory hyperpigmentation. The more we can limit melanin production, the less hyperpigmentation problems we will have. Luckily for us, there are a slew of products that inhibit melanin by telling tyrosinase to chill out. “Just chill out dude!” I can hear them confronting him already.

The concept behind increasing cell turnover to help PIH is pretty straight forward. The faster your cells renew and shed off old skin, the less time we’ll have to wait for PIH to go away.

Here’s an extensive list of ingredients and products that either inhibit tyrosinase or increase cell turnover rate. For the sake of keeping this article short, I’ll only be giving a quick summary of each ingredient. As time passes by, I will be updating this by linking informationally exhaustive posts about each ingredient in case you want to read more about a specific one.

The products listed can be found on Amazon and are ones I have either tried or believe in. If you have any other recommendations, let me know.

Product Recommendations.

AHAs (glycolic, lactic, mandelic).Increase cell turnover. Exfoliates the surface of skin. Better for dry skin.
Recommendations:PC's 8% AHA Gel (Full Review); Drunk Elephant TLC Framboos Glycolic Night Serum; Cosrx AHA 7 Whitehead Power Liquid. Related reading: Best Glycolic Acid Products: Top 5 Picks From A Skincare Junkie
Arbutin.Tyrosinase-inhibitor. Safer form of hydroquinone. Better for lighter skin types.
Recommendations:Hada Labo Shirojyun Albutin Medicinal Whitening Lotion; Benton Snail Bee High Content Essence (Holy Grail)
Azelaic Acid.All-star ingredient. Powerful tyrosinase-inhibitor. Antibacterial, antioxidant, anti-keratinizing.
Recommendations:GIGI Bioplasma Azelaic Cream 15%; Ecological Formulas Melazepam Cream; 15% Skinoren Gel
BHA (Salicylic Acid).Unclogs pores, exfoliates, treats hyperpigmentation.
Recommendations:Paula's Choice Regular Strength 2% BHA; Paula's Choice Skin Perfecting 2% BHA Liquid (Full Review Here); Stridex Pads (Full Review Here); Full Review Here)
Fermented Rice.Contains kojic acid, a tyrosinase inhibitor. Good for dull skin.
Hydroquinone. Potent tyrosinase-inhibitor. Anything above 2% requires prescription. I personally never had luck with hydroquinone products and prefer arbutin instead. YMMV though.
Kojic Acid.Tyrosinase-inhibitor. Works synergistically with hydroquinone.
Licorice Root Extract.Tyrosinase-inhibitor. Gentle, calms the skin.
Recommendations:Drunk Elephant C-Firma Day Serum; SCINIC Honey All In One Ampoule
N-Acetyl Glucosamine.Tyrosinase-inhibitor. Works synergistically with Niacinamide.
Niacinamide.All-star ingredient. Antioxidant, increases collagen production and skin hydration, reduces hyperpigmention.
Recommendations:CeraVe AM Moisturizer (Sunscreen); CeraVe PM Moisturizer (Full Review Here); EltaMD AM Therapy (Full Review Here); EltaMD UV Clear SPF 46 (Sunscreen; Full Review Here); SCINIC Honey All In One Ampoule
Retinoids (Tretinoin [requires Rx], Retinol).Increases collagen and cell turnover, fights hyperpigmenation.
Recommendations:Differin (first FDA approved OTC prescription strength Retinoid). Full Review Here; Paula's Choice Clinical 1% Retinol Treatment with Peptides & Vitamin C
Soy.Antioxidant. Fights hyperpigmention.
Tranexamic Acid.Reduces melanin production. Works synergistically with Niacinamide.
Recommendations:My Beauty Diary Tranexamic Acid Radiance Mask
Vitamin C (SAP).Fights acne. Lightens skin. Gentle. No side effects.
Recommendations:Mad Hippie Vitamin C Serum (Full Review Here)
Vitamin C (ascorbic acid/L-AA).All-star ingredient. Antioxidant, promotes collagen, photoprotective properties, lightens skin.
Recommendations:Dr Brenner 20% Vitamin C; NuFountain® C20®+Ferulic Vitamin C; Drunk Elephant C-Firma Day Serum; Timeless 20% Vitamin Serum; Skinceuticals C E Ferulic; Related Reading: Best Vitamin C Serums: Top 5 Picks for Glowing Skin

Hope you found this useful!



Correct people about what type of “acne scar” they have! Share this! 🙂