Acne Marks Don't Have to Be Forever: Understanding and Treating PIH and PIE
The spots have finally cleared, but they've left marks behind. It's one of the most common concerns patients bring to me, and one of the most frustrating, because the marks can last far longer than the acne did. Many people end up covering them with make-up, or simply waiting and hoping they'll fade.
The reassuring news is that these marks are usually not scars. They're changes in the colour of the skin rather than permanent damage to its texture, and there are effective ways to improve them. The key is understanding which type you have, because the two most common types are different conditions and need different treatments.
Why are the marks still there?
Acne is an inflammatory condition. Even after a spot has healed, the inflammation can leave visible changes in the skin. These usually show up in one of two ways:
Brown or dark marks: post-inflammatory hyperpigmentation, or PIH
Pink, red or purplish marks: post-inflammatory erythema, or PIE
These are different from acne scars, which are dips or raised areas that change the surface of the skin. Scars need a different approach, which I cover at the end.
PIH: brown marks
When skin is inflamed, the pigment cells in it can go into overdrive and produce extra melanin. Once the spot heals, that extra pigment is left behind as a flat brown, dark brown or greyish mark.
PIH is more common, and often longer lasting, in medium and darker skin tones. Sunlight darkens it and slows its fading, which is why sun protection is so important.
PIE: red marks
PIE isn't pigment at all. It's persistent redness caused by small blood vessels near the surface of the skin that were widened or damaged during the inflammation and haven't settled back down.
PIE is more common in lighter skin tones and can linger for many months.
PIH and PIE at a glance
PIH | PIE | |
Colour | Brown, dark brown or grey | Pink, red or purple |
Cause | Extra pigment (melanin) | Widened small blood vessels |
More common in | Medium and darker skin tones | Lighter skin tones |
Glass test | Stays the same colour | Fades under pressure |
Laser we use | PicoSure Pro | DermaV |
A simple way to tell them apart
Press a clear glass gently against the mark. If it fades under the pressure, it's likely PIE, because you're pushing the blood out of those small vessels. If it stays the same colour, it's likely PIH.
Many people have a mixture of both. Treating pigment as if it were redness, or the other way round, often gives disappointing results, which is why a proper assessment matters.
Seeing what's beneath the surface
At the clinic I use a Meicet Pro-A skin analysis camera. It photographs your skin under different light settings, which separates brown pigment from redness and shows marks that aren't yet visible to the naked eye. It shows clearly which type of mark you have and how extensive it is, helps me plan the right treatment, and lets us track how your skin improves from one visit to the next.
Your assessment
Before recommending any treatment, I look at:
whether you have PIH, PIE or a combination of both
your skin type and how readily your skin pigments
whether you still have active acne or another inflammatory skin condition
how deep and widespread the marks are
the health of your skin barrier and any treatments you've tried before
what you'd like to achieve, and what fits your lifestyle
How PIH and PIE are treated
Because they have different causes, PIH and PIE are treated differently, and many people benefit from a combination of professional treatment and the right home care.
For brown marks (PIH): the starting point is usually daily sun protection and skincare that helps regulate pigment. Where marks persist, the PicoSure Pro laser can help. It delivers energy in pulses lasting trillionths of a second, which break excess pigment into tiny particles that the body clears away naturally. Because it works with very little heat, it's gentle on the surrounding skin, which matters with pigmentation, as too much heat or irritation can make it worse, particularly in darker skin tones. A patch test is carried out first where appropriate.
For red marks (PIE): the DermaV laser targets the blood in those small, widened vessels, gently heating them so they close and the body reabsorbs them. As the vessels settle, the redness fades. Gentle, barrier-supporting skincare helps too, because irritation can keep redness going.
Most people need between one and four sessions, spaced four to six weeks apart. Where someone has both types, I often combine the two lasers in one treatment plan. Every skin responds differently, so I'll always give you a realistic idea of what to expect at your consultation.
Looking after your skin at home
Professional treatment works best alongside a consistent home routine:
Wear a broad-spectrum SPF 50 every day, even in winter. If you're prone to pigmentation, a tinted sunscreen gives extra protection against visible light.
Cleanse gently and use a moisturiser that supports your skin barrier.
Use pigment-regulating ingredients such as vitamin C, niacinamide, retinol or azelaic acid, as recommended for your skin. Azelaic acid at strengths of up to 10% is available over the counter without a prescription, and is particularly useful because it helps with both brown marks and redness.
Don't pick or squeeze spots, and avoid harsh scrubs. More inflammation means more marks.
Get active acne under control, so new marks don't keep forming.
What if it's a scar?
If an area is indented or raised rather than just a different colour, it's an acne scar. Scars respond to treatments that work on the texture of the skin, such as microneedling or UltraClear laser resurfacing.
You don't have to settle for uneven skin. With a careful assessment, the right treatment and a good skincare routine, we can work towards clearer, calmer, more even-looking skin.
Post-acne marks can affect your confidence long after the acne itself has gone. Whether you have stubborn brown marks, lingering redness or a mixture of both, understanding what's happening in your skin is the first step to improving it.
Book a consultation
Every treatment starts with a face-to-face consultation, where I'll assess your skin with the Meicet Pro-A camera, explain what's causing your marks and recommend a plan that suits you. The consultation fee is £25, refunded when you attend or put towards your treatment.
Dr Pratish Dholakia, BDS FDSRCS (Eng), GDC 71109
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