Post-Inflammatory Hyperpigmentation

Is it a True Acne Scar?

Post-inflammatory hyperpigmentation
Post-inflammatory hyperpigmentation. Photo © A.D.A.M.

Your acne is clearing up and your skin is looking better every day. But then you notice dark pink or brown spots on your skin where the acne lesions have healed. Is it scarring? And what can you do about it?

What is Post-Inflammatory Hyperpigmentation?

Post-inflammatory hyperpigmentation, or PIH, is the medical term given to discoloration of the skin that follows an inflammatory wound. It is the skin's natural response to inflammation.

Post-inflammatory hyperpigmentation looks like a flat area of discoloration on the skin (these flat, discolored areas are also called macules.)  It can range in color from pink to red, purple, brown or black, depending on your skin tone and depth of the discoloration.

PIH develops when a scrape, rash, pimple, or other wound causes your skin to become inflamed.  As the skin heals, it sometimes produces too much melanin. Melanin is the protein in the skin that gives the skin its color.

It's the excess melanin that darkens and discolors the skin. This discoloration remains even after the wound or rash has healed.

Unfortunately, PIH is very common in those with acne. It can develop in all skin types, but it's more common in darker skin tones. It affects both men and women equally.

PIH and Acne

Inflamed pimples often leave PIH spots behind after they heal. And it's not just the big blemishes that cause these spots.

  PIH macules can follow even relatively minor pimples and papules.

However, the more inflamed a breakout, the larger and darker the PIH macule tends to be. Picking or popping a pimple increases the chance of developing post-inflammatory hyperpigmentation, simply because you're increasing inflammation.

Treating PIH

Post inflammatory hyperpigmentation is not a scar in the true sense of the word.  It can fade away over time, even without treatment.  But it can take a long time -- from a few weeks to 24 months to fully fade. 

The length of time it takes for PIH to fade depends on how dark the PIH macule is compared to your skin tone. The bigger the contrast between the macule and your natural skin tone, the longer it will take to fade.

Some post-inflammatory hyperpigmentation spots last longer, though, and can be permanent.  There are treatment options available to help fade even the most stubborn post-inflammatory hyperpigmentation spots.

First, though, your acne should be more-or-less under control before beginning any treatment for PIH. Otherwise, each new pimple could cause another PIH macule, reducing the effectiveness of treatment.

Whatever treatment option you choose, understand that improvement will take time. Think in terms of months rather than weeks.

Also, many dermatologists recommend using a broad-spectrum sunscreen daily. The sun may darken the discolorations and increase fading time.

Over-the-Counter Treatments
Mild cases of post inflammatory hyperpigmentation can respond well to over-the-counter products.

There is a plethora of "brightening" treatment products on the market today.

Look for a combination of alpha and beta hydroxy acids (including glycolic acid), vitamin A, vitamin C, and other ingredients to exfoliate the skin.  Other OTC ingredients that may be helpful are N-acetyl glucosamine and niacinamide.

Hydroquinone is a widely used treatment for post inflammatory hyperpigmentation. It is available over-the-counter at 1% to 2% strength, and in 3% to 4% prescription creams. Hydroquinone works by blocking the enzyme responsible for melanin production, thereby lightening the skin.

Hydroquinone creams often contain additional lightening ingredients, such as kojic acid, glycolic acid, tretinoin and other retinoids, or vitamin C. These combination creams can give you better results than using hydroquinone alone.

Hydroquinone creams should be carefully applied to darkened areas only, to prevent the unwanted lightening of your natural skin color. Hydroquinone may cause skin irritation for some people. It's worth talking to your doctor before beginning hydroquinone treatment.

Topical Retinoids
Retinoids, such as tretinoin and tazarotene, are often prescribed to treat acne. Retinoids help clear acne by speeding up cell turnover rates.

This rapid exfoliation can also help clear PIH. Retinoid creams include Retin-A, Tazorac, and Differin. The fact that they lessen post inflammatory hyperpigmentation as they treat acne breakouts is an added bonus.

Obvious results may not be apparent for several weeks to several months after beginning treatment.  Also, be on the lookout for excessive dryness, redness, and irritation.  This can trigger post-inflammatory hyperpigmentation on its own.

Glycolic Acid
Glycolic acid is an alpha hydroxy acid found in many skin care products. It effectively exfoliates the skin, helping to lighten post inflammatory hyperpigmentation. Available in cleansers, creams, and gels, glycolic acid not only helps improve postinflammatory hyperpigmentation ​but also leaves your skin smooth and soft.

Cleansers, gels, pads, and lotions containing glycolic acid are available over-the-counter. Higher concentrations are available with a prescription only. As with all products, improvement may not be seen for several months. Monitor your skin for irritation, and let your doctor know if it occurs.

Next steps:

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Azelaic Acid
Azelaic acid is used to treat acne as well as PIH. Available by prescription only, azelaic acid works by decreasing inflammation and speeding up cell turnover rates. Some studies have shown azelaic acid to be as effective as hydroquinone at treating hyperpigmentation. It is a good alternative for those who may be unable to use hydroquinone.

Azelaic acid is available in cream and gel form and is sometimes used in conjunction with glycolic acid or tretinoin.

As always, monitor your skin for redness and irritation and let your doctor know right away if you experience these side effects.

Procedural Treatments
More persistent cases of post inflammatory hyperpigmentation can be treated professionally at skin spas, medi-spas, or your dermatologist's office. Procedural treatments include various chemical peels and microdermabrasion. A series of treatments is needed to adequately fade PIH. Your doctor can help determine which of these treatments, if any, would be right for you.


Cayce KA, Feldman SR, McMichael AJ. "Hyperpigmentation: a review of common treatment options." Journal of Drugs in Dermatology (2004); 3(6):668-73.

Halder RM, Richards GM. "Topical agents used in the management of hyperpigmentation." Skin Therapy Letter (2004); 9(6):1-3.

Palumbo A, d’Ischia M, Misuraca G, Prota G. "Mechanism of inhibition of melanogenesis by hydroquinone." Biochem Biophys Acta (1991); 1073(1):85-90.

"Skin of Color." American Academy of Dermatology. 2006..

Kimball AB, Bissett DL, Robinson LR. "Topical formulation containing N-acetyl glucosamine and niacinamide reduces the appearance of hyperpigmented spots on human facial skin." Presented at: the 64th Annual Meeting of the American Academy of Dermatology, San Francisco, CA; March 3-7, 2006.

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