Acne Scars vs Dark Spots: What Fades and What Needs Treatment

Most marks left after a pimple heals are not scars. Flat pink, red or purple marks (post-inflammatory erythema) and flat brown or grey marks (post-inflammatory hyperpigmentation) are colour changes that usually fade on their own over months, faster with daily sunscreen and the right topical. True scars change the skin’s texture, either as dents or raised bumps, and don’t go away without procedures. Here’s how to tell which you have and what the evidence says about each.

What’s the difference between acne scars and dark spots?

The simplest test is touch and texture. Run a finger over the mark, or look at it with light coming from the side. If the skin is flat and only the colour is different, it’s a mark. If there’s a dip, pit or raised bump, it’s a scar. The American Academy of Dermatology (AAD) puts it plainly: flat red, brown or white spots left after acne are usually not scars, and they tend to fade over time.

Post-inflammatory hyperpigmentation (PIH): brown, grey or dark spots

PIH happens when inflammation triggers extra melanin production. StatPearls notes it’s more common and severe in darker skin tones (Fitzpatrick types III to VI), and that PIH can affect as many as 65% of people with darker skin who have acne. Its depth matters: pigment in the top layer of skin looks tan to dark brown and tends to improve within 6 to 12 months, while pigment deeper in the dermis looks blue-grey and is more persistent, sometimes permanent.

Post-inflammatory erythema (PIE): pink, red or purple marks

PIE is redness that lingers after a spot heals. A short 2013 report in the Journal of Clinical and Aesthetic Dermatology describes it as mostly affecting lighter skin types (I to III), distinct from PIH because it’s residual redness rather than a pigment change, and says both tend to resolve over time. That report is based on case examples, and I couldn’t find a well-established timeline for how long PIE lasts.

Depressed (atrophic) scars

These form when the skin makes too little collagen while healing. The AAD says most people with acne scars get this type, and describes three shapes: ice pick (narrow and deep), boxcar (round or oval with defined edges) and rolling (wide and shallow, giving a wavy texture).

Raised (hypertrophic and keloid) scars

These form when the skin makes too much collagen. The AAD notes they are more common in darker skin tones; hypertrophic scars tend to appear on the jawline and trunk 1 to 2 months after a breakout, while keloids are oversized raised scars that can appear 3 to 12 months after acne clears. Back and chest acne are covered in back acne.

What causes acne scars, and can you prevent them?

The AAD lists three main risk factors: deep, inflamed acne such as nodules and cysts (the deeper the spot, the more likely a scar), picking or squeezing spots, and having a close relative who scarred. The most useful prevention is treating acne effectively and early, and applying acne medication to spots instead of popping them (see should you pop pimples?).

Does sunscreen really help dark spots fade?

It’s the foundation. StatPearls lists daily broad-spectrum sunscreen first among PIH treatments, and the AAD recommends SPF 30 or higher, broad-spectrum and water-resistant, and specifically a tinted sunscreen containing iron oxides, which also blocks the visible light that can darken spots in deeper skin tones. Choose non-comedogenic formulas if you’re acne-prone; more in moisturizer and sunscreen for acne.

What does the evidence say about azelaic acid and retinoids?

Azelaic acid

Azelaic acid is appealing because it treats acne and pigment at the same time. In a 2024 randomised, double-blind, placebo-controlled trial in 60 people who completed 12 weeks, 15% azelaic acid gel reduced both PIE and PIH significantly more than placebo and improved quality of life scores. Two-thirds of the azelaic acid group had mild redness, tingling, dryness, itching or peeling, which settled within about a week. An earlier 16-week open-label pilot study in 20 adults with darker skin (types IV to VI) also reported improvements in both acne and PIH with 15% gel twice daily, but it was small and unblinded. So: promising, moderate-sized evidence. The AAD describes azelaic acid as thought to be safe during pregnancy. More in azelaic acid for acne.

Topical retinoids

A 2022 review of retinoids in skin of colour summarises the evidence: a 40-week double-blind trial found tretinoin 0.1% cream lightened PIH in Black patients, with improvement from as early as week 4, but about half had skin reactions; an open-label study of adapalene 0.1% in 44 people with moderate acne showed promising PIH results; and an 18-week trial of tazarotene 0.1% cream significantly reduced hyperpigmentation versus vehicle. The same review flags an important catch: retinoid irritation can itself cause more hyperpigmentation in darker skin, so a slow start and good moisturiser matter. Retinoids should be avoided in pregnancy; the AAD advises stopping adapalene and tretinoin while pregnant.

What about hydroquinone and “fade creams”?

Hydroquinone is a classic PIH treatment listed by StatPearls, but in the US it is now prescription-only. The FDA says OTC skin-lightening products containing hydroquinone have been misbranded since September 2020, and it has received reports of rashes, facial swelling and ochronosis (a bluish-black skin discoloration that may be permanent). The AAD also warns that some imported lightening products have contained steroids or mercury.

What procedures treat acne scars?

Because depressed and raised scars are structural, creams alone rarely fix them; the AAD says retinoids or salicylic acid can only make mild scarring less noticeable. Options a dermatologist may offer for depressed scars include laser resurfacing, chemical peels, microneedling (with or without radiofrequency or platelet-rich plasma), fillers, dermabrasion and minor surgery such as subcision. Raised scars may be treated with corticosteroid injections, lasers, surgery or freezing. The AAD notes that if you still have active breakouts, treatment usually starts with getting acne under control.

The evidence is honestly thin. A 2016 Cochrane review of 24 small trials (789 participants) found moderate-quality evidence only that fillers beat placebo; most other comparisons were very low quality, and no study showed that short-term gains last. The StatPearls PIH chapter also cautions that peels and lasers can themselves trigger more hyperpigmentation if not done carefully, which matters most for darker skin. NICE suggests referring people with severe persistent scarring a year after acne clears to services that offer CO2 laser or glycolic acid peels. After any procedure, the AAD advises daily SPF 30+ sunscreen and avoiding tanning.

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