PIE vs PIH: red and brown acne marks explained simply

When you have lived with acne, it is very tempting to call every leftover mark a scar.

I get it. The pimple leaves, the mark stays, and emotionally the skin still feels unfinished. Very rude behaviour from a spot that was already annoying while it was active.

But the label matters.

Over the last 15 years, I have helped more than 100,000 people with problem skin, and I have seen a lot of people treat the wrong leftover problem. They use brightening serums for red vascular marks. They use red-light devices for brown pigment. They use scar creams on flat marks. Then they feel like their skin is impossible.

Often, the skin is not impossible. The map is wrong.

The short answer

PIE means post-inflammatory erythema. These are flat red, pink, or purple marks after acne.

PIH means post-inflammatory hyperpigmentation. These are flat brown, grey, or darker marks after acne.

Acne scars are texture changes: pits, dents, rolling shadows, or raised tissue.

So the quickest test is:

• Flat and red or pink? Probably PIE.
• Flat and brown, grey, or darker? Probably PIH.
• Dented, pitted, wavy, or raised? More likely a scar.

That is not a medical diagnosis, but it is a useful starting point before choosing what to do next.

What PIE is

PIE is the red or pink leftover mark after inflammation.

It often shows up more visibly in lighter skin tones, but anyone can have post-acne redness. The colour comes from healing inflammation and tiny blood vessels near the surface of the skin.

A 2022 systematic review^[2] describes post-acne erythema as red marks left after acne inflammation and notes that light and laser-based treatments are frequently studied for persistent cases.

In normal routine terms, PIE usually wants:

• Fewer new breakouts.
• No picking.
• Barrier support.
• Sunscreen.
• Time.
• Professional advice if redness persists for months.

Brightening ingredients may help the overall tone, but PIE is not mainly a pigment stain. That is why a "dark spot corrector" can feel disappointing when the mark is red.

What PIH is

PIH is pigment after inflammation.

After acne, the skin can produce extra melanin in the healing area. The result is a flat mark that looks brown, tan, grey, or darker than the surrounding skin. In deeper skin tones, PIH can be more common, more noticeable, and more stubborn.

A 2010 review^[1] describes post-inflammatory hyperpigmentation as a common consequence of inflammatory skin conditions and highlights photoprotection plus topical pigment treatments as core management.

In practical terms, PIH usually wants:

• Daily SPF.
• Less new acne.
• No picking.
• Pigment-supporting ingredients.
• Patience.

PIH is where ingredients like azelaic acid, niacinamide, retinoids, vitamin C, kojic acid, tranexamic acid, or dermatologist-supervised hydroquinone may be relevant.

What true acne scars are

True acne scars change the structure of the skin.

A 2017 review^[3] explains acne scars by wound healing and collagen changes after inflammation. If too little collagen support forms, the scar can become indented. If too much forms, it can become raised.

Common texture scars include:

• Ice pick scars: narrow, deep pits.
• Boxcar scars: wider depressions with clearer edges.
• Rolling scars: soft waves or shadows.
• Hypertrophic or keloid scars: raised thickened tissue.

Skincare can support the skin around scars. It cannot reliably fill a deep pit or release a tethered rolling scar. That is professional-treatment territory.

The simple at-home check

Look at the mark in natural light.

First, check the surface:

• Does the skin feel flat when you gently run a clean finger over it?
• Does the mark disappear or change mostly with lighting?
• Is there a shadow from a dip?
• Is there a raised edge?

Then check the colour:

• Red, pink, or purple points more toward PIE.
• Brown, grey, tan, or darker points more toward PIH.
• Mixed colour is common.

Now stretch the skin gently beside the mark.

If the mark is mostly colour, stretching may make the surface look normal but the colour remains. If it is a scar, the shadow or indentation often remains because the structure is changed.

Do not obsess over this test. It is a guide, not a legal proceeding against your face.

Why people confuse PIE and PIH

Because real skin does not label itself neatly.

One breakout can leave a red mark first, then a brown mark later. Some marks look purple or grey and sit somewhere between categories visually. Some people have active acne, red marks, brown marks, and pitted scars in the same area.

That is normal.

The goal is not perfect classification. The goal is choosing a routine that does not make things worse.

What to do if it is PIE

For red marks, think calm first.

Use:

• Gentle cleanser.
• Moisturiser or barrier support.
• Daily sunscreen.
• Acne control that your skin tolerates.
• Redness-supporting ingredients such as azelaic acid or niacinamide if they suit your skin.

Avoid:

• Harsh scrubs.
• Daily strong acids.
• Picking.
• Over-cleansing.
• Treating redness with products that sting every time.

If PIE is persistent and bothersome, a dermatologist may discuss vascular lasers, IPL, or other professional options.

What to do if it is PIH

For brown or grey marks, think pigment prevention plus pigment support.

Use:

• SPF every morning.
• Acne control.
• Azelaic acid, niacinamide, retinoids, vitamin C, or other pigment-supporting ingredients as tolerated.
• A routine boring enough to repeat.

Avoid:

• Irritating the skin in the name of speed.
• Picking.
• Skipping sunscreen.
• Strong DIY treatments.

PIH often fades slowly. The most important thing is not restarting inflammation every week.

What to do if it is a scar

If the skin has texture changes, keep skincare realistic.

Your routine should still:

• Reduce new acne.
• Protect from UV.
• Support the barrier.
• Avoid picking and irritation.

But for established pits, dents, rolling shadows, or raised scars, book a dermatologist or experienced acne-scar clinic. Options may include microneedling, laser, subcision, TCA CROSS, fillers, or scar-specific injections depending on the scar.

The acne scars guide goes deeper on that decision.

My final advice

Before treating an acne mark, ask two questions:

1. Is it colour or texture?
2. If it is colour, is it mostly red or mostly brown?

That tiny pause can save months of frustration.

PIE needs calm and sometimes vascular help. PIH needs sunscreen and pigment support. Scars need structural thinking.

And all three need the same emotional ingredient: less punishment. Your skin already did the hard job of healing. Help it finish calmly.