Guide · Post-inflammatory erythema
Post-inflammatory erythema why red acne marks linger, and what fades them
Red or pink marks after a breakout are neither pigment nor scars. Here is how post-inflammatory erythema (PIE) differs from brown PIH, why it can hang around for months, and which treatments have evidence behind them.
Quick answer
- Post-inflammatory erythema (PIE) is the flat pink, red or purplish mark left where an acne spot was inflamed. It comes from small blood vessels in the upper skin that stay widened after the inflammation, not from extra pigment, and it is not a scar.
- PIE is told apart from post-inflammatory hyperpigmentation (PIH) by colour and by pressure: PIE is pink to red and fades briefly when a clear glass is pressed on it, while PIH is brown or grey-brown and does not. Many people in Singapore have both at once.
- Most PIE fades on its own over weeks to months once breakouts stop. Controlling active acne, daily sunscreen, gentle skincare and not picking do most of the work; brightening creams and pigment lasers aimed at melanin do little for redness.
- For red marks that persist, vascular lasers and light devices have the most evidence, with pulsed dye laser the most studied. At IN Eternity Clinic, Dr Sin Yong uses Laser Toning (1064 nm Q-switched Nd:YAG) and 少女光 (675 nm) laser for redness, priced at consultation; SkinRev Lab does not perform lasers.
The basics
What is post-inflammatory erythema?
Post-inflammatory erythema is the redness that stays behind after an inflamed pimple has healed. The surface is flat and the texture is normal, but the spot looks pink, red or slightly purple, especially when you are warm or have just washed your face. Dermatologists Bae-Harboe and Graber proposed the term in 2013 because there was no accepted name for this redness, and people often confused it with pigment marks or scars.
During an inflamed breakout, signalling molecules widen the tiny capillaries in the upper dermis and the skin over the spot thins. After the pimple settles, those vessels can stay dilated for a while, so the area keeps showing red. As the vessels slowly return to normal, the mark fades. That is why PIE is a problem of blood vessels, and why treatments designed for pigment often disappoint.
PIE vs PIH
Red marks vs brown marks: PIE and PIH compared
Many faces in Singapore show both: a pink centre where the vessels are still dilated, with a brown rim of pigment. In a survey of 324 acne patients in seven Asian countries, 58% had PIH, and for more than half of them it lasted at least a year. When both are present, they are usually treated in steps, because the tools are different.
| Post-inflammatory erythema (PIE) | Post-inflammatory hyperpigmentation (PIH) | |
|---|---|---|
| Colour | Pink, red or purplish | Brown, dark brown or grey-brown |
| What causes it | Widened small blood vessels after inflammation | Extra melanin left by overreacting pigment cells |
| Glass press test | Fades briefly under pressure | Stays the same colour |
| Who notices it most | Easier to see on fair to light-medium skin | More common in medium to darker skin, including most Asian skin |
| Usual course | Fades over weeks to months once acne is controlled | Fades over months; deeper grey-brown marks can last a year or more |
| What helps most | Time, sun protection, gentle care, vascular laser or light | Time, sun protection, lightening creams, gentle pigment laser |
| What tends not to help | Pigment-lightening creams and melanin-targeted lasers | Vascular lasers aimed at blood vessels |
Why it lingers
Why red acne marks take so long to fade
The commonest reason is simple: new spots keep forming. Each inflamed pimple starts a fresh red mark, so the face never gets the chance to clear. Picking and squeezing push the inflammation deeper and keep the vessels open for longer.
Irritation does the same. Using strong exfoliating acids, scrubs and high-strength retinoids all at once can leave the skin inflamed and the marks redder. Heat dilates vessels too, so Singapore's hot afternoons, hot showers, saunas and moving between the street and cold air-conditioning can make PIE look worse on some days than others.
Not every persistent red patch is PIE. Rosacea, a damaged skin barrier, seborrhoeic dermatitis and visible thread veins can all look similar. If the redness flushes and fades with triggers, covers the central face rather than individual old spots, or comes with stinging or small bumps, a doctor should check what it is before treatment.
First steps
What fades PIE: the basics that matter most
These steps sound modest, but for most people they are enough. PIE usually settles once the inflammation stops, and the main job is not to keep restarting it.
- Get active acne under control first; fewer new spots means fewer new red marks.
- Use a broad-spectrum sunscreen every day, reapplied when outdoors; Singapore's UV is high all year and also drives the brown PIH that often sits alongside PIE.
- Keep the routine gentle: a mild cleanser, a light moisturiser and lukewarm rather than hot water.
- Introduce retinoids or exfoliating acids slowly, one at a time, and stop anything that stings or leaves the skin red for hours.
- Do not pick, squeeze or scrub healing spots.
- Give it time: judge progress over two to three months, not days, and take photos in the same light to compare.
Creams and serums
Topical treatments: what the evidence shows
A 2022 systematic review of treatments for post-acne erythema found 18 eligible studies and no single gold-standard treatment. Laser and light devices were the most studied. Among creams and gels, tranexamic acid and the vessel-narrowing agents brimonidine and oxymetazoline were described as promising, with no severe side effects reported, but the authors called for more randomised trials.
Brimonidine and oxymetazoline are prescription gels used for the redness of rosacea; their effect on visible redness is temporary and works while they are used, and they are prescribed by a doctor. Brightening ingredients such as niacinamide and azelaic acid are mainly aimed at pigment and inflammation. They can help the brown PIH that often sits alongside PIE and are gentle enough for most acne-prone skin, but their effect on red marks is less certain.
Lasers and light
Vascular lasers and light for red acne marks
Devices whose light is absorbed by haemoglobin can shrink the widened vessels behind PIE. A 2022 review of 12 randomised trials covered pulsed dye laser, intense pulsed light, Q-switched Nd:YAG and several other lasers, and concluded that light and laser treatments are effective for acne-related redness. In a Korean pilot study of 20 patients, two sessions of 595 nm pulsed dye laser four weeks apart improved redness in 90%, with only short-lived redness and swelling as side effects.
Lower-energy 1064 nm lasers have also been tested. In a randomised split-face trial of 26 patients in China, both low-dose Q-switched 1064 nm Nd:YAG and a pulsed light device reduced post-acne redness after six fortnightly sessions, with similar results at the end and no pigment changes. These studies are small and short, so expect improvement over a course rather than a certain, complete clearance.
| Device | How it targets redness | Evidence for PIE | In our network |
|---|---|---|---|
| Pulsed dye laser (585–595 nm) | Yellow light absorbed by haemoglobin in small vessels | Most studied; small trials show improvement over two or three sessions | Not among the lasers listed at IN Eternity Clinic |
| Intense or delicate pulsed light | Filtered broad-band light, partly absorbed by haemoglobin | Randomised trials show benefit | Not among the lasers listed at IN Eternity Clinic |
| Low-dose Q-switched 1064 nm Nd:YAG | Gentle dermal heating; also fades brown pigment | One randomised split-face trial: redness fell after six sessions | Laser Toning, priced at consultation |
| 675 nm fractional laser | Red light into dermal collagen; redness benefit less studied | Studies mainly on texture, ageing and acne scars | 少女光 Laser, priced at consultation |
At IN Eternity Clinic
Red mark treatment by Dr Sin Yong
At IN Eternity Clinic, Dr Sin Yong first confirms that the redness is PIE rather than rosacea, sensitised skin or thread veins, and checks whether brown PIH or early scarring is mixed in. Active acne is brought under control before marks are treated.
For red marks, he may use Laser Toning, a low-energy 1064 nm Q-switched Nd:YAG passed across the face, which can soften diffuse redness while also fading brown pigment, or the 少女光 Laser, a 675 nm fractional laser on the DEKA RedTouch Pro with contact cooling, which suits redness that sits alongside enlarged pores and uneven texture. Research on the 675 nm wavelength for redness is still limited, so it is offered as one option rather than a certain fix.
Where brown PIH is the bigger problem, R2 Glow (a Fotona Nd:YAG brightening course) or Pico Laser may be used instead; these target melanin rather than blood vessels. Sessions are spaced weeks apart, treatment is deferred during a tan or flare, and pricing is given at consultation.
Save your money
What does not help red acne marks
- Whitening or lightening creams aimed at melanin: they target brown pigment, not blood vessels.
- Pigment lasers at strong settings: they are not designed for redness and carry a risk of PIH in Asian skin.
- Home peels, scrubs and stacking several acids: irritation keeps vessels dilated and marks red.
- Squeezing or extracting healed marks: there is nothing to remove, and it restarts inflammation.
- Expecting one facial or one session to clear it: PIE improves gradually, and new spots will add new marks.
- Products promising to erase marks in days: redness from vessels does not disappear that quickly.
Where to go
PIE care in our network
Lasers for persistent red marks are medical treatments. At IN Eternity Clinic, 9 Scotts Road, #12-01 Pacific Plaza, beside Orchard MRT, Dr Sin Yong assesses the marks and, where suitable, performs Laser Toning or 少女光 Laser. Both are priced at consultation by the clinic; WhatsApp +65 8815 3008.
SkinRev Lab, at CityLink Mall #B1-28 by City Hall MRT, is a non-invasive centre and does not perform lasers. SKINLDM (S$288 before GST, first visit S$68) uses dual-frequency ultrasound to calm reactive, inflamed skin, and HydraFacial Syndeo (S$288 to S$438 before GST; first-timer rate at the counter) helps keep congestion and new spots down. Neither closes the vessels behind PIE, and the team will say so; WhatsApp +65 8266 9585.
Sources
References & sources
- Bae-Harboe YS, Graber EM. Easy as PIE (postinflammatory erythema). J Clin Aesthet Dermatol. 2013;6(9):46-47.
- Kalantari Y, Dadkhahfar S, Etesami I. Post-acne erythema treatment: a systematic review of the literature. J Cosmet Dermatol. 2022;21(4):1379-1392.
- Amiri R, Khalili M, Mohammadi S, Iranmanesh B, Aflatoonian M. Treatment protocols and efficacy of light and laser treatments in post-acne erythema. J Cosmet Dermatol. 2022;21(2):648-656.
- Yoon HJ, Lee DH, Kim SO, Park KC, Youn SW. Acne erythema improvement by long-pulsed 595-nm pulsed-dye laser treatment: a pilot study. J Dermatolog Treat. 2008;19(1):38-44.
- Liu H, Zhang L, Gao Z, et al. Comparison of the efficacy of low-energy delicate pulsed light and Q-switched 1064 nm Nd:YAG laser in the treatment of post-acne erythema: a prospective randomized split-face study. Lasers Surg Med. 2025;57(9):716-725.
- Abad-Casintahan F, Chow SK, Goh CL, et al. Frequency and characteristics of acne-related post-inflammatory hyperpigmentation. J Dermatol. 2016;43(7):826-828.
Common questions
Your questions,
answered
What is post-inflammatory erythema?
It is the flat pink, red or purplish mark left where an inflamed acne spot has healed. It comes from small blood vessels that stay widened after the inflammation, not from pigment, and it is not a scar. It usually fades over weeks to months.
How long does post-inflammatory erythema last?
It varies. Many red marks fade within a few months once breakouts stop, but some persist for longer, especially if new spots keep forming or the skin stays irritated. Sun protection, gentle skincare and not picking help it fade; persistent marks can be treated with vascular laser or light.
What is the difference between PIE and PIH?
PIE is red or pink and comes from blood vessels; it fades briefly when a clear glass is pressed on it. PIH is brown or grey-brown and comes from extra melanin; pressure does not change it. They need different treatments, and many people have both.
Do red acne marks go away on their own?
Most do, given time, once active acne is controlled. Treatment speeds things up rather than replacing patience. If a red patch has not changed after several months, or flushes and spreads, see a doctor to rule out rosacea or other causes.
What is the fastest way to get rid of red acne marks?
There is no instant fix. Stopping new breakouts, daily sunscreen and a gentle routine come first. For marks that persist, vascular lasers and light devices have the most evidence, usually over two to six sessions spaced weeks apart. Results vary between people.
Does niacinamide or vitamin C help PIE?
These ingredients mainly target pigment and inflammation, so they can help brown PIH and calm the skin. Their effect on redness from blood vessels is less certain. A systematic review found tranexamic acid, brimonidine and oxymetazoline promising for post-acne redness, but more trials are needed.
Can laser make red acne marks worse?
Lasers cause temporary redness and swelling, which settle in hours to days. In Asian skin any heat-based treatment can trigger temporary brown marks, so settings are conservative, treatment is deferred during a tan, and sunscreen is used throughout. Tell the doctor if you darken easily.
Is PIE a type of acne scar?
No. PIE is a colour change with normal texture. The same inflamed spot can, however, also leave a dent or raised scar. If the area casts a shadow in side lighting or feels uneven, it is a scar, which needs different treatment.
How much does PIE laser treatment cost in Singapore?
It depends on how widespread the redness is and how many sessions are needed. At IN Eternity Clinic, Laser Toning and 少女光 Laser are priced at consultation after Dr Sin Yong has examined the marks. When comparing anywhere, ask about the whole course, not one session.