PIE is easy to identify once you know what to look at. It is flat, it is red rather than brown, and it lightens when you press on it.
PIE is easiest to see in fair and light skin, where it reads as obvious pink or red. In brown and Black skin it is often present but harder to spot, appearing as a subtle purple, plum or dusky-brown mark rather than red — and it is frequently mistaken for post-inflammatory hyperpigmentation. Many people with medium and dark skin have both at once in the same spot, which is worth knowing, because the two need different treatments and treating only one leaves half the mark behind. The blanch test still works, and it is more reliable than colour on darker skin.
If your mark is brown, does not blanch, or has a dip in it, see Lookalikes near the bottom of this page.
When skin is inflamed — by a pimple, a cut, a rash, a burn or a procedure — the body widens the small blood vessels in the area to bring in the cells that do the repairing. That is a normal and useful part of healing.
Sometimes those vessels do not fully close down again once the repair is finished. They stay dilated and slightly leaky near the surface, and the blood inside them shows through the skin as a flat pink or red mark. That is all post-inflammatory erythema is: a healing response that has not quite switched off. There is no scar tissue, no lost collagen, and no extra melanin involved.
Who gets it is largely about skin type. Fair skin shows it most, and people who flush easily or have rosacea are more prone. Picking and squeezing makes it far more likely and far more intense, because it deepens and prolongs the inflammation. In brown and Black skin, the same inflammation more often triggers melanocytes to produce extra pigment as well, which is why post-inflammatory hyperpigmentation is the more common complaint there — but PIE happens too, and often alongside it.
Nothing here clears redness quickly, and the main job of an at-home routine is to stop new marks forming while the current ones fade. One popular category is included specifically so you know to skip it.
PIE fades on its own, so most people never need a visit. It is worth going if:
What the visit gets you: a definitive answer on red versus brown — usually with a glass slide pressed against the skin, which takes seconds; acne treatment that stops new marks forming; and access to pulsed dye laser or IPL, which are the only things that reliably speed the fading.
Prescription options for PIE are mostly aimed at controlling the acne underneath. Two vessel-constricting creams exist, and it is worth understanding what they do and do not do.
These are the only treatments that target the dilated vessels causing the redness, and the only ones that reliably shorten the timeline. Usually considered after six months of waiting.
The mark looks its most intense. This is normal and not a sign that anything is going wrong.
Slow fading from red toward pink. Progress at this stage is easier to see in photos than in the mirror, so take one at the start.
Most marks fade substantially or disappear. This is the usual full course, and it happens with or without products.
Marks still clearly visible at this point are less likely to clear on their own, and this is the sensible moment to consider laser or IPL rather than another cream.
Expect three to five sessions, three to four weeks apart. Redness and mild swelling for a day or two after each. Pulsed dye laser can leave a bruise-like mark for up to a week if stronger settings are used.
PIE resolves completely in most people. It is a temporary mark, not a scar. The main things that keep it around are ongoing acne and continued picking — and no treatment outruns either of those.
PIE is a cosmetic mark rather than a medical problem, and it clears in most people. The complications are mostly about what happens around it.
This is the section that matters most on this page, because PIE is misidentified constantly.