Post-Inflammatory Erythema

The negative effects of acne is underestimated, usually not by the patients, but by the public, parents, and unfortunately, sometimes doctors as well. This month we look into a side-effect of acne that is often misidentified: Post-inflammatory erythema or PIE.

Acne can roughly be divided into comedonal (blackheads and whiteheads) and inflammatory (pimples, pustules) acne1. Acne is frustrating enough, and has serious psychosocial effects and can affect quality of life for patients in significant ways, even in cases where the acne is relatively mild. On top of that, acne is an inflammatory condition, and as such, it has the potential to leave a trail of damage afterwards:

Scars: Scars are an underestimated risk of acne. Scarring is a permanent change in the structure of the skin. Scars will often cause a change in texture, and can often be felt by touch. The most common acne scars are atrophic scars where there are dips in the skin’s surface, but there are also other types of scarring that can occur.

Post-Inflammatory Hyperpigmentation (PIH): A darkening of the skin where the acne was present; with PIH, the inflammation triggers melanocytes to overproduce melanin. PIH is a significant risk and concern for patients with a darker skin type. PIH will generally fade away with time even without treatment, but it can take up to months or even years2.

Post-Inflammatory Erythema (PIE): Post-inflammatory erythema is a relatively new term in dermatology3. On the other hand, patients have been frustrated for much longer with this - PIE refers to the red spots that don’t seem to leave the face even after the acne has subsided.

Note that these conditions are not mutually exclusive. It’s common that patients with moderate to severe acne will often have some combination of PIH and PIE, and unfortunately, sometimes acne scars present in combination.

What Is PIE and How Does It Form?

Post-Inflammatory erythema (PIE) are the red spots that form in the area where pimples and pustules (inflammatory acne) used to be present. They are macules, a change in color from skin color to pink or red and aren’t elevated or depressed. PIE is not acne-specific, as it can occur in response to any inflammatory process in the skin. PIE is essentially a vascular problem - and the cause of redness is simply in the blood vessels that have become more visible.

How Do You Treat PIE?

Patients with chronic acne will often have various signs of acne, either scarring, post-inflammatory hyperpigmentation (PIH) or post-inflammatory erythema (PIE) to some degree. Many treatments overlap, but the key is to treat the acne first. Treating the after-effects without treating the acne is not as effective, as new acne may cause further damage anyway. In terms of treating PIE, no treatment is a legitimate option as most cases of post-inflammatory erythema are self-limiting, and will fade away over time. However, there are treatment options available to help remove them faster:

  • No Treatment: Always an option. For most people, as long as the acne is controlled, the redness of PIE will fade away with time. Unfortunately, this could be several months or longer for some.
  • Pulsed Dye Lasers: These lasers are used to treat vascular lesions without damaging the surrounding tissues, and are also effective for removing the redness in post-inflammatory erythema.
  • Silicone Sheeting: These sheets are a recent addition to treating scarring, and the evidence for it working for PIE is sparse4, but may be an option worth trying as they are inexpensive products.

1We are now learning that technically, acne always starts with inflammation (even when it’s not visible), and may be an important factor in its pathogenesis.