Post-inflammatory hyperpigmentation (PIH): Causes and Treatment

As its name suggests, post-inflammatory hyperpigmentation happens after skin injury or inflammation, leaving the skin darkened and discoloured once the wound has healed. 

Read below to learn what post-inflammatory hyperpigmentation is, what it looks like, and the treatments to reduce dark spots and patches on your skin.

Post-inflammatory hyperpigmentation (PIH) refers to dark spots or patches that develop on the skin after injury or inflammation, such as from acne or burns.

It can affect anyone; men and women are equally susceptible, but it’s more common in people with darker skin tones. Typically, it appears as flat dark spots of discolouration and an uneven skin tone. These spots range in colour from brown to black, depending on skin tone and the depth of discolouration. While PIH usually subsides over time, treatments are available to help accelerate the process.

The more inflammation there is, the more obvious the area of discolouration will be, both in terms of size and colour. In cases where PIH is caused by acne, picking pimples can worsen the skin condition, leading to increased hyperpigmentation. PIH can also appear on the legs as a result of abrasions from shaving. 

In some cases, inflammatory acne can result in pink, red, or purple coloured pigmentation, which is more commonly referred to as post-inflammatory erythema (PIE). PIE refers to discolouration due to damage to capillaries in the skin’s surface, whereas PIH mainly refers to the pigment change following a skin condition. Both PIE and PIH tend to reduce with time, although acne scarring can be textural and permanent.

The root cause of PiH is increased melanin production. Melanin is the pigment that defines the color of a person’s skin and the increase in melanin is triggered by the way skin heals after inflammation or injury.

1- Postinflammatory hyperpigmentation: a review of the epidemiology, clinical features, and treatment options in skin of color. E.C. Davis and V.D. Callender. J Clin Aesthet Dermatol. 2010 Jul; 3(7): 20-31/em>

An injury, rash, or blemish causes the skin to become inflamed. This inflammation triggers melanocytes, the cells that produce melanin, to release an excess of pigment granules called melanosomes. These overproduction pigment granules darken and discolour the previously wounded area, remaining there long after the initial wound has healed.

When the skin heals, it produces extra melanin (the pigment that gives skin its colour) in the affected area, causing it to become darker than the surrounding skin. Other common causes of PIH include: 

• Acne 
• Injuries: Cuts, scrapes, or surgical incisions 
• Skin conditions: eczema, psoriasis, and dermatitis 
• Burns: Thermal or chemical burns 
• Insect bites 
• Allergic reaction 
• Hair removal: waxing or threading
• Friction: tight clothing or repeated scratching

Whilst not the cause of PIH, the sun can aggravate symptoms, darkening the affected patches and prolonging the time it can take for them to fade. The sun is closely associated with other forms of hyperpigmentation, such as age spots, also known as sun spots, and melasma. 

Post-inflammatory hyperpigmentation is harmless, but melanoma can be life-threatening. If you have any concerns about your dark pigment spots – if they change shape, size, and colour, or if they become itchy and start to bleed, it’s important that you consult your doctor. 

Post-inflammatory hyperpigmentation does not cause scarring, and even with no treatment, it will improve over time.

There are several ways to improve symptoms and speed up recovery of post-inflammatory hyperpigmentation.

Chemical peels involve applying a chemical solution (such as an AHA) to exfoliate skin (remove dead skin cells), stimulate the growth of new skin cells, and reveal new skin.

Laser therapy has a similar effect but tends to be more precise as the dermatologist has more control over the intensity of the treatment. Laser treatments involve ‘zapping’ the affected areas with high-energy light. The mildest treatments work on the skin’s epidermis (surface layer), while more intense treatments can penetrate the deepest layers of the skin. Find out how best to care for your skin after laser therapy.

Dermatologists may also prescribe and/or use hydroquinone to help reduce melanin production, which is still regarded as the most effective topical agent for reducing post-inflammatory hyperpigmentation. However, it can only be used for limited periods of time because, like other forms of chemical peel and laser treatment, it can irritate skin and actually cause post-inflammatory hyperpigmentation.

Dermo-cosmetic and anti-pigment skincare products can be used daily to help extend the results of dermatological treatments. Eucerin DermoPurifyer Skin Renewal Treatment is a dermatologist-recommended, oil-free facial fluid that targets three types of imperfections: blemishes, post-acne marks, and comedones. It combines 2% Salicylic Acid (BHA) with patented Thiamidol to visibly reduce spots, unclog pores, and regulate oil.

If your skin is injured or prone to blemishes, or if you have skin conditions like atopic dermatitis or psoriasis, taking care of your skin is crucial to reduce the risk of post-inflammatory hyperpigmentation. Appropriate medication and/or a regular skincare routine using products that have been specially formulated to address your skin’s needs will help.

Blemish-prone skin is more likely to develop blemishes, such as pimples, blackheads, whiteheads, and other types of acne. If you have acne-prone skin, you should have a proper skincare routine to prevent PIH from appearing. Eucerin DermoPurifyer contains Licochalcone A and Salicylic Acid, which are effective anti-inflammatories that soothe irritation, help reduce redness and blemishes, and prevent them from reappearing.

Atopic skin, also known as atopic dermatitis or atopic eczema, is a chronic skin condition characterised by dry, itchy, and inflamed skin. The itchiness induces scratching, which makes symptoms worse and can lead to skin infection; it also tends to flare up periodically. Eucerin AtopiControl Acute Care Cream has been specially formulated to relieve skin during a flare-up. It offers intensive care: reducing itching, moisturising skin, and strengthening its natural barrier.

There is a higher chance of post-inflammatory hyperpigmentation after dermatological treatment for acne, such as chemical peels, dermabrasion, and laser therapy. Eucerin Aquaphor Soothing Skin Balm is enriched with Glycerin and Panthenol, which help to speed up regeneration and repair while also moisturising skin. This balm has been clinically and dermatologically proven to repair very dry, cracked, and irritated skin, helping to prevent the appearance of PIH.

A sensible attitude to sun protection will also help to prevent or reduce the severity of PIH:

• Limit the time you spend in the sun - keep out of the sun during its most intense hours 
• Wear protective clothing and sun hats whenever possible
• Apply a sun protection product that offers the level of protection your skin needs and that is proven to be suitable for your skin type and/or condition. 

Eucerin Sun Protection helps prevent PIH and includes face and body products that are suitable for blemish-prone skin, atopic skin, and skin that has recently undergone dermatological treatments.