Acne scars: 8 things you probably don't know
Nearly one in two people still bear the scars of acne in the form of brown spots, redness, pits, or bumps that can persist for years and undermine self-confidence. The good news is that dermatological research in recent years has clarified the mechanisms involved and identified effective—and sometimes little-known—strategies for preventing, reducing, or correcting these marques.
1. Marks or scars? The 12-month tipping point
- Transient post-inflammatory marks : brown spots (pigmentation) or redness (erythema) that usually fade within a year.
- Real scars : any alteration remaining visible more than 12 months after the initial injury, whether indented (atrophic) or raised (hypertrophic/keloid), reflecting a lasting reorganization of the dermis.
2. Hyperpigmentation
During inflammation, cytokines activate melanocytes; excess melanin accumulates and colors the healed area. Dark skin types are more prone to this, with pigmentation lasting 6 to 18 months. The most well-documented active ingredients in 2024 for reducing this production are:
- azelaic acid 15 % (significant reduction in pigment density in 12 weeks)
- niacinamide 4-5 %
- stable vitamin C derivatives
- AHA/BHA/PHA exfoliants < 20 %
Daily sun protection remains the cornerstone of prevention: a recent study confirms that SPF 50 sunscreen limits post-inflammatory hyperpigmentation (PIH), even on dark skin.
3. Persistent redness
Prolonged dilation of the superficial capillaries explains the pink to red coloration, which is more apparent on fair skin types. These are the active ingredients to prioritize for reducing post-inflammatory erythema:
- Glycerin, hyaluronic acid : sustained hydration
- Vitamin C, azelaic acid : anti-inflammatory agents accelerate resorption
4. When the skin structure breaks down
There are three classic types of atrophic scars:
- “Ice pick” : narrow, deep V-shaped trenches
- “Boxcar” : wide craters, sharp or rounded edges
- “Rolling” : diffuse ripples creating an uneven surface
These shapes reflect collagen loss and underlying fibrous adhesion.
5. Excess collagen
Prolonged inflammatory stimulation can trigger uncontrolled collagen production. Lesions remain raised (hypertrophic scars), sometimes extending beyond the initial area (keloids). Intralesional corticosteroid injections remain the standard treatment for flattening these growths.
6. Prevention remains the most cost-effective strategy
- Treat active acne early Delaying treatment increases the severity of the aftereffects.
- Prohibit manual “drilling” : mechanical injury and risk of secondary infection.
- Maintain the skin barrier : ceramides, fatty acids, humectants.
- Sun protection 365 days a year : Sunlight intensifies pigmentation and redness.
7. Topical treatments
The following formulations have been the subject of recent studies:
- Azelaic acid : anti-inflammatory, tyrosinase inhibitor.
- Niacinamide : blocks the transfer of melanosomes.
- Retinoids : accelerate cell renewal and stimulate collagen.
- AHA/BHA/PHA : controlled exfoliation promoting a more even complexion.
Regular use for 8 to 12 weeks is necessary for visible results.
8. Dermatological procedures
- Fractional CO laser₂ : major clinical improvement in atrophic scars, especially rolling scars“
- Microneedling : An analysis from 2024 shows that the combination of microneedling and chemical peeling is the most effective way to achieve an objective reduction in skin texture.
- Fractional radiofrequency, medium TCA peels and subcision complete the arsenal depending on the depth and morphology of the lesions.
- Hyaluronic acid filler : useful for mild depression, reversible effect at 8-12 months.
