Acne can leave behind dark marks due to a process known as post-inflammatory hyperpigmentation. When an acne lesion forms, whether it is a whitehead, blackhead, or inflamed papule, the body mounts an immune response to address bacteria, excess sebum, and cellular debris inside the clogged pore. This inflammatory response triggers the release of signaling molecules that stimulate melanocytes, the pigment-producing cells in the skin. As melanocytes increase melanin production in response to inflammation, darker patches can remain even after the active acne lesion has healed.
The severity of inflammation plays a central role in how noticeable these marks become. Deeper or more inflamed acne lesions, such as nodules or cysts, tend to produce stronger inflammatory signals, which may result in more pronounced pigmentation changes. Repeated manipulation of acne, including squeezing or picking, can intensify inflammation and increase the likelihood of dark marks. Although post-inflammatory hyperpigmentation is not a true scar, it can persist for weeks to months, especially in individuals with medium to deeper skin tones, where melanocytes are more reactive.
Sebum production and clogged pores indirectly influence this process by determining how frequently inflammatory acne develops. When excess oil combines with abnormal follicular keratinization, microcomedones form and may evolve into inflamed lesions if bacterial overgrowth occurs. The more frequently inflammation occurs, the greater the cumulative risk of pigmentation changes. In this way, effective acne control not only reduces breakouts but may also limit the formation of residual dark marks.
Ultraviolet exposure can further worsen post-inflammatory hyperpigmentation. Sunlight stimulates melanocytes and can deepen existing discoloration, prolonging its visibility. For this reason, daily use of sunscreen is often recommended as part of a comprehensive acne management routine. Lightweight, non-comedogenic formulations can help protect the skin without contributing to clogged pores.
Treatment strategies for dark marks typically focus on both controlling acne and addressing pigment production. Topical retinoids may help by accelerating cell turnover and improving the dispersion of melanin over time. Azelaic acid is often used because it can support normalization of keratinization while also helping to reduce excess pigmentation. Niacinamide may assist in improving uneven skin tone and reinforcing the skin barrier. Salicylic acid can help maintain clearer pores, reducing the risk of new inflammatory lesions that could lead to additional marks. Improvement generally occurs gradually, as pigment fades slowly through natural skin renewal.
It is important to distinguish post-inflammatory hyperpigmentation from true acne scars, which involve structural changes in the skin. Dark marks typically fade with time, whereas scars may require procedural treatments. Individuals experiencing persistent discoloration or scarring may benefit from consultation with a qualified dermatology professional to determine appropriate options.
Understanding why acne leaves dark marks highlights the importance of early and consistent management. By reducing inflammation, avoiding picking, supporting the skin barrier, and protecting against sun exposure, many individuals can minimize the duration and intensity of post-acne discoloration while maintaining overall skin health
