What is post-inflammatory erythema?

It is quite common to have pigmented spots after acne. Different from the post-inflammatory hyperpigmentation, which is more characteristic of darker skin types, post-inflammatory erythema appears as pink to red spots where the blemishes were previously located. Although they can have a real impact on the uniformity of the complexion and self-confidence, these marks are not considered scars as they gradually fade over time. However, their complete disappearance can be quite lengthy and takes several months.

As its name suggests, post-inflammatory erythema results from a skin inflammation. In the case of inflammatory acne, hyperseborrhea is accompanied by the proliferation of the bacterium Cutibacterium acnes. This microorganism thrives in oily environments by feeding on sebum. Cutibacterium acnes plays a major role in inflammation: indeed, it digests the triglycerides present in the sebum and releases pro-inflammatory fatty acids, thereby causing inflammation of the sebaceous glands.

Inflammation then triggers a local immune response in the skin, during which certain immune cells such as neutrophils and macrophages are recruited. Concurrently, chemical mediators of inflammation like interleukins and prostaglandins are released into the skin. They amplify skin inflammation and stimulate vasodilation. The increase in blood vessel diameter results in an intensified blood flow to the infected area, with the aim of providing immune cells with the necessary nutrients and oxygen to combat pathogens. However, this vasodilation can also cause local redness, leading to post-acne erythematous marks. This redness can persist even after the acne has disappeared and the tissues have healed.

Unlike an atrophic or hypertrophic scar, a post-inflammatory erythema usually eventually fades away. This rather lengthy process can be accelerated through the regular application of certain cosmetic actives or via dermatological techniques.

Cosmetic treatments for reducing post-inflammatory erythema.

• Proper skin hydration...

  Hydration is a key factor in healing. To accelerate the disappearance of erythematous marks, we advise you toapply a moisturizing treatment daily, containing, for example, panthenol or Centella asiatica. Also known as provitamin B5, the former is an active ingredient recognized for its ability to absorb moisture from the air to increase the water content of the stratum corneum. The Centella asiatica is an Asian plant with a similar mechanism of action, which also has anti-inflammatory and soothing activity.

• ... supplemented with active ingredients targeting inflammation.

  The disappearance of post-inflammatory erythema can also be accelerated by incorporating anti-inflammatory actives into one's skincare routine. Among the most renowned are azelaic acid, niacinamide, bisabolol, turmeric, ferulic acid, and licorice extract. Acting at different stages of inflammation, these molecules help to reduce redness and allow the skin to regain its uniformity.

Diminishing Erythematous Spots: A Closer Look at Dermatological Techniques.

• The laser.

  The use of lasers, such as Nd-YAG lasers, has demonstrated its effectiveness in various studies. This procedure should only be performed by a trusted healthcare professional, and is preferably carried out in winter. It must be accompanied by strict sun protection in the days before and after the session. The principle of the laser is based on the emission of a specific wavelength that destroys inflamed skin cells. Multiple sessions may be necessary before visible results are achieved.

• Pulsed light.

  Using a process similar to that of a laser, pulsed light differs by its broader range of emitted wavelengths (between 500 and 1200 nm). Its ability to significantly reduce erythematous marks has been demonstrated in various studies. In a recent study conducted with 33 patients suffering from post-inflammatory erythema, 3 to 6 sessions of pulsed light improved the color and texture of the skin in the majority of patients and led to the near disappearance of marks in 27 of them. However, temporary pigmentation disorders (hyper- or hypopigmentation) were encountered by 9 patients.

• Radiofrequency.

  Primarily known for its effect on signs of aging, fractional radiofrequency can also be used to reduce post-inflammatory erythema. By emitting an electric current, it creates coagulation zones at various depths of the skin to stimulate the activity of fibroblasts, the cells that synthesize collagen and elastin. The purpose of radiofrequency is to induce a tissue regeneration. A recent study showed a significant reduction in post-inflammatory erythema in 25 patients with no side effects after two sessions of radiofrequency.

While erythematous marks usually fade away over time, preventing them through certain precautionary measures remains the best solution. For this, we advise you tosee a dermatologist without delay to treat your acne as soon as possible, before the pimples spread across your skin and leave spots, or even scars. A tailored follow-up with a healthcare professional will save you time in your fight against acne.

In parallel, it is essential to properly hydrate your skin daily, even if you have oily skin. Indeed, this step is crucial to limit insensible water loss, which affects all skin types, to ward off external aggressions, and thereby, rebalance the sebum level. Good hydration also strengthens the skin barrier, which promotes healing. Moreover, to avoid amplifying inflammation and spreading the infection, avoid handling your pimples. This will not make them disappear faster, on the contrary.

Finally, it's important to know that sun exposure intensifies post-inflammatory erythema and prolongs the healing time. Therefore, make sure to protect yourself daily from UV rays by applying a broad-spectrum SPF sunscreen. If you need to go out during the hours of the day when the sun is at its highest, which is between 11 a.m. and 4 p.m., we advise you to wear sunglasses and a wide-brimmed hat or a cap.

• BAE-HARBOE Y. S. & GRABER E. M. Simple as PIE (Postinflammatory Erythema). The Journal of Clinical and Aesthetic Dermatology (2013).

• SUH D. H. & al. Fractional Microneedling Radiofrequency Treatment for Acne. Acta Dermato-Venereologica (2015).

• ABAD-CASINTAHAN F. & others. Frequency and characteristics of post-inflammatory hyperpigmentation related to acne. The Journal of Dermatology (2016).

• AISWARYA V. & al. Intense Pulsed Light Therapy for Acne-induced Post-inflammatory Erythema. Indian Dermatology Online Journal (2018).

• ETESAMI I. & al. Treatment of Post-Acne Erythema: A Systematic Review of the Literature. Journal of Cosmetic Dermatology (2022).

• AFLATOONIAN M. & al. Treatment protocols and efficacy of light and laser treatments in post-acne erythema. Journal of Cosmetic Dermatology (2022).