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Post-inflammatory erythema (PIE) and post-inflammatory hyperpigmentation (PIH) are two common skin conditions triggered by factors such as acne, injuries, or inflammation. They are often wrongly referred to as acne scars, though all three differ. PIE materializes as reddish or pinkish blemishes on the skin, primarily resulting from dilated blood vessels, while PIH is characterized by the presence of dark, pigmented patches due to excessive melanin production. Distinguishing between these conditions and genuine acne scars can make it easier to get appropriate treatment and prevention strategies. Below, we will explore the differences between PIE and PIH, explain how they differ from different types of acne scars, and delve into effective treatment options for each.

The Difference Between PIE vs PIH

Post-inflammatory hyperpigmentation (PIH) and post-inflammatory erythema (PIE) are two common types of skin discoloration that can occur as a result of inflammation or injury, such as acne. While they may share some similarities, understanding the differences between PIH and PIE can help these marks fade faster and prevent future marks from appearing.

What is PIH?

PIH (Post-inflammatory hyperpigmentation) is the term used for dark brown, black, or tan patches that appear on the skin after inflammation or injury. Inflammatory responses or trauma prompt the body to release more melanin, which accumulates in the affected area. This causes the characteristic dark patches of PIH. PIH is more common in darker skin tones.

If untreated, PIH can last for several months or years. The melanin deposits in the skin take a long time to fade, so consistent and targeted treatment is necessary to reduce its appearance.

What is PIE?

PIE appears as flat, red or pink marks on the skin. Inflammation or trauma prompts the release of inflammatory substances, leading to blood vessel expansion. The increased blood flow in the affected area causes the redness associated with PIE. Unlike the darker pigmentation seen in PIH, PIE is lighter and most often affects those with lighter skin tones.

Unlike PIH, PIE usually fades within a few months. The red or pink marks gradually diminish as the blood vessels return to their normal state. However, factors like the inflammation’s severity or individual skin characteristics may affect this timeframe.

Acne Scars and How They Differ from PIE and PIH

True acne scars are noticeably different from post-inflammatory erythema (PIE) and post-inflammatory hyperpigmentation (PIH). Unlike PIE or PIH, acne scars are a permanent alteration in the skin’s structure due to the disruption of collagen fibers, which are essential for maintaining its elasticity and smoothness.

How are Acne Scars Formed?

Acne scars form during the healing process of severe or deep acne lesions. The inflammation and trauma from these lesions can disrupt the normal collagen production, which is responsible for supporting the skin’s structure. This disruption leads to scar formation.

There are different types of acne scars, each with their own unique characteristics. Common types of acne scars include:

  • Ice-pick scars: Ice-pick scars are deep, narrow, and pitted in appearance. They resemble small, deep holes or punctures in the deeper layers of the skin. They can be challenging to treat due to their depth.
  • Rolling scars: Rolling scars are broad depressions with a sloping edge, giving them a rolling or wave-like appearance resulting from damage to the underlying collagen fibers.
  • Boxcar scars: Boxcar scars are broad, rectangular depressions with sharply defined edges. Their distinct edges give them a punched-out appearance on the skin’s surface.
  • Atrophic scars: Atrophic scars refer to flat, thin, or depressed scars. These scars may appear as shallow indentations on the skin.
  • Hypertrophic or keloid scars: Hypertrophic and keloid scars are both types of raised scars. Hypertrophic scars are thick, lumpy scars. Keloid scars are similar but extend beyond the boundaries of the original injury and may continue to grow over time.

Differences Between Acne Scars and PIH/PIE

Acne scars differ from PIE and PIH in their permanence. While PIE and PIH fade with time, acne scars typically last. Once collagen is disrupted and a scar forms, it can be difficult to treat. Acne scars can appear as pitted or depressed areas, raised bumps, or indented or raised marks. In contrast, PIE and PIH are flat hyperpigmentation marks.

Due to their permanent nature, treating true acne scars requires specific interventions, usually from licensed skincare professionals. Options include laser resurfacing, dermal fillers, chemical peels, microneedling, subcision, or surgical removal. Sometimes, a combination of treatments may be needed for best results. On the other hand, PIE and PIH can often improve or resolve through topical treatments, skincare routines, and proper skincare practices.

Causes of PIH and PIE

Post-inflammatory hyperpigmentation (PIH) and post-inflammatory erythema (PIE) are common forms of skin discoloration that can occur as a result of inflammation or injury, such as acne breakouts.

Both PIH and PIE can be influenced by individual factors, including skin type, skin color, skin sensitivity, and the intensity of the inflammatory response. These factors play a role in determining the severity and duration of the discoloration. Individuals with darker skin tones may be more prone to PIH, while PIE may be more noticeable in individuals with fairer or lighter skin.

Causes of PIH

PIH is caused by an overproduction of melanin, the pigment responsible for skin coloration. When the skin experiences inflammation or trauma, the body releases excess melanin, which accumulates in the affected area.

Some common causes of PIH include:

  • Acne breakouts: When acne lesions heal, they can leave behind PIH as a result of melanin overproduction in response to the inflammation caused by acne.
  • Insect bites or allergic reactions: Inflammatory reactions triggered by insect bites or allergic reactions can lead to PIH. The skin’s response to the irritation and inflammation caused by these external factors can result in the overproduction of melanin, causing pigmented spots to form.
  • Skin injuries or burns: Trauma or injury to the skin, such as cuts, burns, or surgical wounds, can result in PIH. The skin’s natural healing response involves inflammation, and when this inflammatory process is disrupted or prolonged, it can lead to the development of hyperpigmentation.

Causes of PIE

PIE appears as flat, red or pink marks on the skin. It occurs due to the dilation of blood vessels in response to inflammation or injury. The increased blood flow in the affected area causes the erythema associated with PIE.

Common causes of inflammation or injury that can cause PIE include:

  • Acne breakouts: The dilation of blood vessels as part of the skin’s inflammatory response to acne can result in red or pink PIE marks.
  • Picking or squeezing pimples: Picking or squeezing pimples can worsen inflammation and trauma to the skin which can lead to prolonged blood vessel dilation and the development of PIE.
  • Trauma or injury to the skin: Any trauma or injury to the skin, such as scratches, abrasions, or cuts, can trigger PIE. The damaged skin and subsequent inflammation cause the blood vessels to dilate, resulting in red or pink PIE marks.

Treatment and Prevention of PIH and PIE

Treatments for PIE and PIH share similarities but also have distinct approaches. PIH treatments aim to reduce melanin production, enhance skin cell turnover, and fade the darkened areas. In contrast, PIE treatments focus on anti-inflammatory measures to decrease redness and soothe the skin.

How to Fade PIH

Treatments for post-inflammatory hyperpigmentation (PIH) aim to lighten and fade excessive melanin that leads to skin darkening. Various strategies can be used, such as topical products like hydroquinone, retinoids, or azelaic acid to regulate pigmentation and promote an even skin tone. Procedures like chemical peels or laser therapy can also stimulate skin cell turnover and quicken the fading of PIH-induced dark spots.

Topical PIH Treatments

Many topical products are available that can help lighten and fade PIH. These products focus on brightening and exfoliating in order to reduce the hyperpigmentation associated with PIH.

Look for products containing ingredients such as:

  • Hydroquinone: Hydroquinone is a widely used skin-lightening ingredient that inhibits melanin production. It can be found in over-the-counter products or prescribed by a dermatologist.
  • Retinoids: Topical retinoids, such as tretinoin or adapalene, can help improve skin cell turnover, leading to the gradual fading of PIH.
  • Azelaic acid: Azelaic acid has both brightening and anti-inflammatory properties, making it effective in reducing hyperpigmentation.
  • Vitamin C: Vitamin C, or ascorbic acid, is a potent antioxidant that helps brighten the skin and fade hyperpigmentation. It inhibits melanin production and promotes collagen synthesis, leading to a more even complexion.
  • Niacinamide: Niacinamide, or vitamin B3, offers multiple benefits for the skin. It helps regulate melanin production, improves skin barrier function, and reduces inflammation.
  • Kojic Acid: Kojic acid is a natural ingredient derived from certain fungi and is known for its skin lightening properties. It inhibits tyrosinase activity, reducing melanin production and fading PIH spots.
  • AHAs: AHAs are water-soluble acids that exfoliate the skin’s surface, revealing fresh, new skin underneath. AHAs also promote collagen synthesis and can help fade hyperpigmentation, including PIH.
  • BHAs: While BHAs, such as salicylic acid, primarily target acne-related concerns they can also indirectly help fade PIH by improving the overall clarity and texture of the skin and minimize the potential for new breakouts that can cause PIH.

Procedures to Fade PIH

If you want to fade PIH marks faster or have severe PIH discoloration, there are treatments and procedures available that can be performed by dermatologists or other professionals.

Chemical peels: Chemical peels involve applying a chemical acid, such as AHAs, BHAs, or phenol, to the skin. This causes controlled exfoliation, promoting the growth of new, healthier skin and fading PIH spots. The peel’s depth and strength can be adjusted based on the pigmentation’s severity.

Microdermabrasion: Microdermabrasion is a type of exfoliation that uses a handheld device with fine crystals or a diamond-tipped wand to gently exfoliate the skin’s outermost layer. This procedure removes dead skin cells and stimulates skin cell turnover, reducing PIH spots. It is a less invasive option compared to chemical peels and may require multiple sessions for optimal results.

Laser therapy: Laser treatments can target and break down excess pigment in the skin. Different types of lasers, like Q-switched lasers or fractional laser resurfacing, can be used for PIH treatment. The laser energy selectively targets the pigment, causing it to fragment and fade gradually. Multiple treatment sessions may be necessary for desired outcomes.

Intense pulsed light (IPL) therapy: IPL therapy employs broad-spectrum light to target pigmented areas of the skin. The light energy is absorbed by the melanin in PIH spots, breaking down the pigment and promoting fading. IPL is effective for treating larger areas affected by PIH and can improve overall skin tone and texture.

Cryotherapy: Cryotherapy uses extreme cold temperatures to freeze and destroy excess pigment in the skin. It is typically used for smaller areas of PIH and can be done using liquid nitrogen or specialized cryo probes.

How to Fade PIE

Like PIH, PIE treatments aim to reduce hyperpigmentation. In the case of PIE, however, the focus is on managing inflammation and minimizing visible redness. Topical treatments containing ingredients like niacinamide, green tea extract, or licorice root extract can soothe and calm the skin, reducing redness and promoting an even complexion. In addition, gentle skincare routines, avoiding potential irritants, and preventing sunburn are equally important for managing PIE.

Topical PIE Treatments

Topical treatments for PIE focus on soothing redness, reducing inflammation, and brightening the skin.

Look for skincare products to target PIE with ingredients such as:

  • Niacinamide: This form of vitamin B3 has anti-inflammatory properties, calms the skin, and promotes an even skin tone.
  • Vitamin C: A potent antioxidant, vitamin C brightens the skin and fades red marks while aiding in the healing process of PIE.
  • Licorice Extract: With soothing and anti-inflammatory effects, licorice extract helps reduce redness and fade PIE marks.
  • Centella Asiatica: Also known as gotu kola, this ingredient has anti-inflammatory properties that calm the skin and promote wound healing.
  • Tranexamic Acid: Known for reducing hyperpigmentation and redness, tranexamic acid targets the underlying inflammation and blood vessel dilation to fade PIE marks.
  • Green Tea Extract: Rich in antioxidants, green tea extract soothes inflammation and contributes to fading red marks while calming the skin.
  • Azelaic Acid: With anti-inflammatory and skin brightening properties, azelaic acid helps fade redness and promote an even skin tone.

Dermatology Procedures to Fade PIE

For more severe cases of PIE, or if you want to see results more quickly, there are some in-clinic skincare procedures available.

Common procedures to fade PIE include:

Laser Treatments: Laser therapies, such as pulsed dye lasers (PDL) or vascular lasers, are commonly used for PIE treatment. These lasers emit specific light wavelengths absorbed by the blood vessels causing redness. The laser energy selectively heats and destroys the vessels, leading to their closure and fading of red marks. Laser treatments are precise and can be customized based on skin type and severity.

Intense Pulsed Light (IPL) Therapy: IPL therapy uses broad-spectrum light absorbed by the red pigments in blood vessels. The light energy heats the vessels, causing them to coagulate and fade over time. IPL is effective for fading PIE and improving skin tone. It is a non-invasive procedure requiring multiple sessions

Vascular-Targeted Photodynamic Therapy (PDT): PDT involves applying a photosensitizing agent to the skin, activated by a specific light source. For PIE, a topical photosensitizing agent is applied, then activated by laser or light. The activated agent targets and destroys the blood vessels responsible for redness, leading to fading of PIE.

Cryotherapy: Cryotherapy involves the controlled application of extreme cold to the skin. It can be used to treat PIE by causing vasoconstriction and reducing blood flow to the affected area. Cryotherapy helps minimize redness and promote skin healing.

How to Prevent PIH and PIE

Both PIE and PIH are caused by skin trauma or inflammation, so prevention measures for both are similar. Here are some prevention tips for PIE and PIH:

Use high SPF sunscreen: Sunscreen is vital in preventing both types of skin discoloration. UV rays can worsen hyperpigmentation and inflammation, making the marks more noticeable. Apply a broad-spectrum sunscreen with SPF 30 or higher daily, reapplying every two hours when exposed to sunlight or outdoor activities.

Avoid picking or popping pimples: Picking or popping pimples can worsen inflammation and increase the risk of developing PIH or worsening existing PIE. It can also introduce bacteria, leading to infection and scarring. Resist the urge to touch or squeeze pimples and allow them to heal naturally.

Maintain a regular skincare routine: Use mild cleansers, toners, serums, and moisturizers that suit your skin type. Avoid excessive use of harsh ingredients or products that can harm the skin, like drying alcohol, aggressive exfoliants, or incompatible ingredients.

Protect your skin during and after skincare procedures: If you undergo dermatological procedures like chemical peels or microdermabrasion, follow your dermatologist’s instructions. Avoid direct sun exposure, use recommended skincare products, and maintain a gentle skincare routine to support healing and minimize the risk of PIE or PIH formation.