Post-inflammatory hyperpigmentation (PIH) is a common skin condition that occurs as a result of an injury, inflammation, or irritation. PIH is characterized by the formation of brown, black, or grayish spots on the skin.
Common causes of post-inflammatory hyperpigmentation include:
- insect bites
- sun exposure
What is Post-Inflammatory Hyperpigmentation (PIH)?
Post-inflammatory hyperpigmentation (PIH) is a condition in which the skin produces excess melanin, leading to the formation of dark spots on the skin. PIH occurs when the skin is injured, inflamed, or irritated. This can happen due to acne, eczema, psoriasis, insect bites, sun exposure, and other skin injuries.
If this sounds like you, check out our article: 5 Effective Ways to Banish Hyperpigmentation Around the Mouth
But if you wanted the nitty gritty science of red light therapy for post-inflammatory hyperpigmentation (and melasma), see my article Is Red Light Therapy Perfect for Hyperpigmentation Reduction?
How Acne Causes Post-Inflammatory Hyperpigmentation
Acne is a common skin condition that can cause inflammation and breakouts on the skin. When acne lesions, such as pimples or cysts, heal, they can leave behind dark spots on the skin known as post-inflammatory hyperpigmentation (PIH).
The reason why acne causes PIH is due to the inflammation that occurs during the healing process. Inflammation triggers the production of melanin, which is the pigment that gives our skin its color. When there is an excess of melanin production, it can lead to hyperpigmentation or darkening of the skin.
The severity of PIH can vary depending on the type of acne and the individual’s skin type. Darker skin types are more prone to developing PIH due to the higher levels of melanin production in their skin.
To prevent PIH from occurring, it is important to treat acne promptly and avoid picking or squeezing acne lesions, as this can worsen inflammation and increase the risk of PIH. Additionally, wearing sunscreen and avoiding sun exposure can also help prevent PIH, as UV rays can worsen hyperpigmentation.
Papules are a type of inflammatory acne lesion that can contribute to post-inflammatory hyperpigmentation (PIH). When a papule forms, the skin’s immune system sends immune cells to the site to fight off the bacteria causing the acne. This process can trigger the production of excess melanin, the pigment that gives skin its color.
In some cases, the excess melanin can become trapped in the skin, leading to dark spots or patches of PIH. This can happen when the immune response is particularly intense, or if the papule is repeatedly irritated or picked at.
It’s important to avoid picking or squeezing papules, as this can worsen inflammation and increase the risk of developing PIH. Treating papules with topical or oral acne medications can help to reduce inflammation and prevent PIH from forming.
Acne cysts are large, pus-filled lesions that develop deep within the skin. They are a severe form of acne and can cause significant inflammation and damage to the skin.
This type of acne can contribute to post-inflammatory hyperpigmentation by causing damage to the surrounding skin cells, which can trigger the overproduction of melanin, resulting in dark spots or patches on the skin.
Cysts can also rupture and spill their contents into the surrounding tissue, causing further inflammation and damage. This can lead to the formation of new blood vessels in the area, which can exacerbate hyperpigmentation.
In addition, cysts can take longer to heal than other types of acne, which means that the inflammation and damage to the skin can persist for a longer period of time, increasing the likelihood of developing post-inflammatory hyperpigmentation.
How Eczema Causes Post-Inflammatory Hyperpigmentation
Eczema is a chronic inflammatory skin condition that affects millions of people worldwide. It is caused by an overactive immune system response to triggers such as stress, allergens, or irritants. When eczema flares up, it can cause intense itching, redness, and inflammation of the affected area.
Post-inflammatory hyperpigmentation (PIH) can occur in people with eczema due to the inflammation and trauma that the skin undergoes during a flare-up. The inflammation triggers the production of excess melanin, which is the pigment that gives skin its color. The excess melanin can then become trapped in the skin cells, leading to hyperpigmentation in the affected area.
Additionally, people with eczema often scratch the affected area to relieve itching, which can cause further damage to the skin and worsen inflammation. This can lead to more severe hyperpigmentation as the skin attempts to heal and recover from the trauma.
How Psoriasis Causes Post-Inflammatory Hyperpigmentation
Psoriasis is a chronic autoimmune disease that affects the skin, causing it to become inflamed and develop scaly patches. These patches, known as plaques, are typically red or pink in color and covered with silvery scales.
When psoriasis plaques heal, they can leave behind areas of hyperpigmentation, which is known as post-inflammatory hyperpigmentation (PIH).
PIH occurs as a result of the body’s natural healing process. When skin is inflamed, it triggers the production of melanin, which is the pigment that gives skin its color. Melanin production increases as a response to inflammation, which can cause areas of the skin to become darker than the surrounding skin.
In the case of psoriasis, the chronic inflammation caused by the disease can result in long-term increases in melanin production. This, in turn, can lead to areas of hyperpigmentation that can persist long after the psoriasis has cleared up. The severity of PIH associated with psoriasis can vary depending on the extent and duration of the inflammation.
How Insect Bites Cause Post-Inflammatory Hyperpigmentation
When an insect bites your skin, it injects its saliva into the skin, which contains a variety of compounds, including proteins and enzymes. The body’s immune system responds to these compounds, triggering an inflammatory response to fight off any potential infection.
During the inflammatory response, immune cells release chemicals such as cytokines and chemokines, which attract more immune cells to the site of the bite. This influx of immune cells causes damage to the surrounding skin tissue, leading to the release of more inflammatory chemicals.
The combination of inflammation and tissue damage caused by insect bites leads to the overproduction of melanin, the pigment that gives skin its color. This excess melanin production causes the dark spots or patches characteristic of PIH.
In addition to inflammation, other factors that can contribute to PIH after an insect bite include sun exposure, genetics, and the severity of the bite. People with darker skin tones are also more prone to developing PIH after insect bites.
To prevent PIH after an insect bite, it’s important to avoid scratching the affected area and to apply topical treatments, such as hydrocortisone cream or aloe vera gel, to reduce inflammation. Sun protection is also crucial, as sun exposure can exacerbate PIH.
How Sun Exposure Causes Post-Inflammatory Hyperpigmentation
Sun exposure causes post-inflammatory hyperpigmentation (PIH) by triggering the production of melanin, the pigment that gives color to our skin, hair, and eyes.
When skin is exposed to the sun, the UV radiation stimulates the melanocytes, which are specialized cells in the skin that produce melanin. Melanin helps protect the skin from further damage by absorbing UV radiation, but it can also result in an overproduction of melanin in certain areas of the skin, causing hyperpigmentation.
Sun exposure can also worsen existing PIH by further stimulating the melanocytes to produce more melanin. This is why it is essential to protect your skin from the sun if you have PIH or are prone to hyperpigmentation.
To prevent PIH caused by sun exposure, it is recommended to use broad-spectrum sunscreen with an SPF of 30 or higher, wear protective clothing, and avoid prolonged sun exposure during peak hours.
Post-inflammatory hyperpigmentation can trigger inflammation that, in turn, causes an over-production of melanin. The result is dark areas in the skin with irregular borders. Avoiding and treating acne, eczema, psoriasis, sun exposure, and insect bites keeps PIH to a minimum.