What is post-inflammatory hyperpigmentation?

You've finally gotten rid of that annoying breakout, but now you're left with a frustrating dark mark that seems to stick around. If this sounds familiar, you might be dealing with post-inflammatory hyperpigmentation (PIH), a common skin issue that occurs after inflammation (1).

Post-inflammatory hyperpigmentation happens when your skin creates a darker spot after healing from an injury or inflammation. These dark spots can prevent you from having an even skin tone, and you might feel frustrated if these marks seem to last for months.

But the good news is that P.I.H. is treatable. If you have hyperpigmentation, this article will help you understand what causes it. It will also teach you how to manage this common condition.

What causes post-inflammatory hyperpigmentation?

Post-inflammatory hyperpigmentation occurs as part of the body’s natural healing response. When the skin is inflamed, it can trigger an overproduction of melanin, the natural pigment responsible for skin colour (2). This can result in a dark patch that can linger long after the initial wound is healed.

Any skin trauma can cause post inflammatory hyperpigmentation (3). One of the most common causes is acne, particularly when blemishes are picked or squeezed. Post-inflammatory hyperpigmentation can also be caused by:

• Eczema flare-ups
• Skin injuries
• Burns
• Insect bites
• Sun damage
• Razor burns
• Impetigo
• Allergic reactions
• Rashes

Sometimes, cosmetic and medical procedures can cause skin pigmentation. These include laser therapy, cryotherapy, chemical peels, and radiation therapy.

In essence, any damage to the skin's surface can lead to the overproduction of melanin. This is the body's natural way to protect the skin. However, in the case of PIH, it causes uneven skin colour.

What does post-inflammatory hyperpigmentation look like?

It can be difficult to identify post-inflammatory hyperpigmentation at first glance, especially because it shares similarities with other skin pigmentation conditions. P.I.H. is characterised by flat patches of skin that are darker than your natural skin tone that appear after skin irritation.

Post inflammatory hyperpigmentation isn't limited by skin type or colour—it can affect anyone, regardless of race or ethnicity—but it looks different on different skin tones. For those with lighter skin, PIH often presents as pink or red patches, whereas on deeper skin tones, it can range from brown to dark brown or even black.

That said, people with darker skin tones are more likely to develop hyperpigmentation in response to inflammation. In these individuals, the melanocytes—the cells that produce melanin (4)—are more active and so more likely to overproduce melanin in response to trauma.

What does post-inflammatory hyperpigmentation NOT look like?

It’s easy to confuse post-inflammatory hyperpigmentation with other skin conditions, such as acne scarring and post-inflammatory erythema (PIE):

• PIH vs acne scarring: Acne scars are permanent changes in the skin's texture caused by severe acne that damages the deeper layers of the skin. They often leave behind raised areas or indentations. By contrast, PIH is purely a pigment issue. These red marks left by spots don’t affect skin texture and fade over time.
• PIH vs post-inflammatory erythema: While PIH refers to dark or brown spots, PIE is a bit different—it’s the red or pink marks that appear, often on fair skin, after inflammatory acne (5). Rather than being caused by an overproduction of melanin, this type of skin pigmentation occurs due to damaged blood vessels.

PIH and its psychological impact

It’s important to recognise that PIH isn’t just a cosmetic issue—it can have psychological effects as well. Many people feel pressure to have clear, flawless skin, and the presence of dark spots and red pimple marks can be a source of frustration, embarrassment, or even shame.

Research shows that people with hyperpigmentation are more likely to experience self-consciousness, social anxiety, and reduced quality of life—even compared to people with other visible skin conditions. One study found that 60% of patients with red marks left by spots had poorer quality-of-life scores than people with only acne (6).

The emotional impact of PIH is often overlooked, but it can be significant. If you’re feeling low about your skin, you can do something about it.

How do you treat hyperpigmentation after inflammation?

Post-inflammatory hyperpigmentation is reversible. Dark marks caused by PIH fade naturally, and you won’t have to deal with these dark spots forever. However, depending on your skin type and the severity of the skin pigmentation, the natural fading process can take months or even years.

You might want to consider hyperpigmentation treatment to speed up the process, which comes in the form of topical and specialist therapies: (7)

Topical treatments

Dermatologists often recommend topical treatments containing adapalene and azelaic acid to address red pimple marks and dark spots. These treatments work by promoting cell turnover and inhibiting melanin production, gradually lightening dark spots over time.

High strength adapalene and azelaic acid creams are only available by prescription. However, over-the-counter products featuring lower concentrations of these or other active ingredients—such as retinol, glycolic acid, and salicylic acid—may help regenerate the skin, potentially aiding in reducing dark spots. While these alternatives can be effective, they won’t deliver the same results as prescription-strength treatments.

Specialist skin treatments

For more persistent hyperpigmentation, dermatologists may recommend specialist treatments like:

• Chemical peels: These work by removing the top layer of dead skin cells, which contain the excess melanin, and promoting new skin growth.
• Laser therapy: Laser treatments can target the excess melanin pigment and break it down, allowing the skin to heal more evenly.
• Microneedling: This involves using tiny sterilised needles to deliver pigment-suppressing ingredients into the deeper layers of the skin (8).

These more specialised treatments do carry risks and can worsen hyperpigmentation in some cases. It’s essential to speak to your doctor to ensure the treatment is correct for your skin tone and the severity of your pigmentation.

How can I prevent post-inflammatory hyperpigmentation?

Knowing how to get rid of red marks left by spots is great, but prevention is always better than cure. While it’s hard to avoid every cause, here are a few things you can do to minimise the risk of PIH:

• Avoid picking spots: Tempting as it may be, picking at your skin only worsens inflammation. Not only does it increase the likelihood of dealing with red marks left by spots, but it also increases the chance of hard-to-treat acne scarring.
• Use sunscreen daily: Sun exposure can darken existing spots and prolong their time to fade, so applying a broad-spectrum SPF every day can help. For those with darker skin tones who are more prone to hyperpigmentation, it’s recommended to use sunscreens containing iron oxide, which provides additional protection against visible light (9).
• Treat acne early: If you’re prone to breakouts, treating acne early can help. The quicker you control inflammation, the lower your chances of developing PIH. Use acne treatments that calm the skin and prevent the formation of new spots to avoid red pimple marks.

Take control of your skin health

Post-inflammatory hyperpigmentation may be frustrating, but it’s not permanent. Understanding what PIH is, why it happens, and how to manage it—whether through treatment or prevention—can help you take control of your skin health.

If you’re ready to address PIH, Oxford Online Pharmacy offers a range of prescription-only hyperpigmentation creams that contain adapalene or azelaic acid to help your dark spots fade. Be sure to check out our article on treating post-inflammatory hyperpigmentation for more detailed advice on your treatment options.

References

1. Lawrence E, Al Aboud KM. Postinflammatory Hyperpigmentation [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2021.
2. Schlessinger DI, Schlessinger J. Biochemistry, Melanin [Internet]. Nih.gov. StatPearls Publishing; 2019.
3. Kaufman BP, Aman T, Alexis AF. Postinflammatory Hyperpigmentation: Epidemiology, Clinical Presentation, Pathogenesis and Treatment. American Journal of Clinical Dermatology. 2017 Dec 8;19(4):489–503.
4. Lin JY, Fisher DE. Melanocyte biology and skin pigmentation. Nature. 2007 Feb;445(7130):843–50.
5. Bae-Harboe YSC, Graber EM. Easy as PIE (Postinflammatory Erythema). The Journal of clinical and aesthetic dermatology [Internet]. 2013;6(9):46–7.
6. Darji K, Varade R, West D, Armbrecht ES, Guo MA. Psychosocial Impact of Postinflammatory Hyperpigmentation in Patients with Acne Vulgaris. The Journal of Clinical and Aesthetic Dermatology [Internet]. 2017 May 1;10(5):18–23.
7. Post-Inflammatory Hyperpigmentation: A Review of Treatment Strategies [Internet]. JDDonline - Journal of Drugs in Dermatology.
8. Wu SZ, Muddasani S, Alam M. A Systematic Review of the Efficacy and Safety of Microneedling in the Treatment of Melasma. Dermatologic Surgery. 2020 Sep 2;46(12):1636–41.
9. Zhou C, Lee C, Salas J, Luke J. Guide to tinted sunscreens in skin of color. International Journal of Dermatology [Internet]. 2024 Mar 1 [cited 2024 Jul 12];63(3):272–6.