The red kind is called postinflammatory erythema, or PIE; the brown kind is postinflammatory hyperpigmentation, or PIH, because even a departed pimple leaves paperwork. You can have both kinds of marks, with or without actual acne scars.3
What does the colour tell you?
| Type of mark | What is happening | Who gets it more often |
|---|---|---|
| Pink or red: PIE | Residual redness after inflammation, rather than extra pigment. | More common in lighter skin. |
| Light brown to black: PIH | Inflammation triggers extra melanin production and pigment deposits. | Can affect anyone, but is more common, more intense and longer lasting in darker skin. |
| Grey, purple or very dark brown pigmentation | Pigment can sit deeper in the skin, not just near the surface. | Depth affects how long the mark takes to fade. |
Are coloured marks acne scars?
A flat patch of colour after a breakout is usually a mark rather than a true scar. A scar changes the skin's texture, leaving a depression or a raised area. Colour and texture can change together, so a scar can also look red or brown. Marks tend to fade; true scars rarely disappear completely on their own. A dark spot and a dent need different treatment approaches, despite being bundled into the same "acne scars" search.35
How long do the marks take to fade?
Acne related colour changes often improve over months or longer. For brown marks, a spot a few shades darker than your usual skin colour usually fades within 6 to 12 months once the cause has stopped. Deeper pigment can take years. Red marks also tend to resolve with time, but there is no reliable single deadline for them. The brown mark timeline is not a countdown for every red mark.134
What should you do about them?
- 1Treat ongoing acne first. Continuing breakouts keep creating the inflammation behind new marks. Wash with a gentle cleanser twice daily, and do not scrub, pick or squeeze spots.
- 2Protect brown marks from sunlight every day. Use broad spectrum SPF 50+ on exposed skin. For darker skin tones, choose a tinted sunscreen containing iron oxide for visible light protection too. Apply before going outside and reapply every two hours, and after swimming or sweating.
- 3For brown marks, consider a pigment fading ingredient such as azelaic acid or vitamin C. These target pigmentation rather than the residual redness of PIE. Follow the chosen product's directions rather than treating every coloured mark as the same problem.
- 4Stop using a skincare product if it burns or stings. Irritation can cause more dark marks, so gentler products matter more than an aggressive fading routine.
For persistent red marks, a dermatologist can discuss a pulsed dye laser, which targets haemoglobin in blood vessels. It has improved PIE in small case reports, but its effectiveness and best settings remain uncertain. For brown marks, peels and some light treatments can help surface pigment, but can also worsen pigmentation by injuring the skin; they do not treat deeper dermal pigment.23
When should you get medical help?
See a doctor if acne is deep, painful, causing scars or not improving with treatment. Hot, swollen skin needs assessment for possible infection. Have new or changing discoloration checked, especially when it does not clearly follow a healed pimple. If persistent pigmentation is not responding, a dermatologist can help choose stronger treatments.467
Where this answer comes from
- 1Acne Scarringdermnetnz.org
- 2Postinflammatory hyperpigmentationdermnetnz.org
- 3Easy as PIE (Postinflammatory Erythema)pmc.ncbi.nlm.nih.gov
- 4How to fade dark spots in darker skin tonesaad.org
- 5Acne scars: Overviewaad.org
- 6Acnenhs.uk
- 7Skin Discoloration: Causes, Conditions & Treatmentsmy.clevelandclinic.org
