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How Sun Exposure Makes Acne Hyperpigmentation Worse

Sun Exposure Triggers Your Skin to Make More Melanin, Leading to More and Darker Pigmentation

By: Dan Kern, Acne.org Founder & CSO
Last updated: October 21, 2019

The Essential Information

The red/dark marks that are left behind after acne lesions heal are known as hyperpigmentation.

These marks are a common problem, particularly in non-Caucasian people.

While sun exposure does not cause post-inflammatory hyperpigmentation, the sun's rays can make existing hyperpigmentation worse by increasing skin pigment (melanin) production, making the red/dark marks more noticeable and longer-lasting.

As a result, dermatologists recommend wearing a broad-spectrum sunscreen with an SPF of 15 or higher to protect the skin and prevent these marks from getting worse or lasting longer than they should.

The Science

Hyperpigmentation refers to any disorder that causes a darkening of the skin, usually in patches or spots, including the darkening of the skin that happens after an acne lesion heals.

Hyperpigmentation occurs due to extra melanin production, and is much more common in people with non-Caucasian skin, who tend to genetically produce more melanin.1

Hyperpigmentation is much more common in non-caucasian skin

Melanin is a natural pigment that gives the skin its color and also protects skin from the sun. It is made by skin cells called melanocytes, which sit at the bottom of the outer layer of skin.1 Since sun exposure creates extra melanin, it can make hyperpigmentation worse. First, let's look at how hyperpigmentation occurs, and then we will explore how the sun makes it worse and why it's important to protect your skin from the sun if you are prone to hyperpigmentation.

How hyperpigmentation occurs

Usually, melanocytes and the melanin they make are equally distributed throughout the skin, leading to an even skin tone. In hyperpigmentation conditions, like hyperpigmentation caused by acne lesions, the skin makes more melanin, in one of two ways:

  1. By increasing the number of melanin-producing melanocytes.
  2. By increasing the amount of melanin the melanocytes make.

Why Hyperpigmentation Occurs

The extra pigment then makes that bit of skin darker than the surrounding area, leading to a noticeable patch or splotch.1,2

In hyperpigmentation that is left behind after acne lesions heal, the spots can be red, brown, or even gray-blue colored, depending on the color of the skin and how deep into the skin the hyperpigmentation goes. These spots can stick around for several months to several years, if not longer, but are not scars and do ultimately fade with time but are sometimes permanent.4,5

Why hyperpigmentation occurs in acne

In acne, the extra melanin results from inflammation at the site of acne lesions. For this reason, it is considered a specific type of hyperpigmentation called post-inflammatory hyperpigmentation.3,4 Regardless of how hyperpigmentation occurs, it is usually treated the same. Specifically, keeping any type of hyperpigmentation out of the sun is important.

How the Sun Makes Hyperpigmentation Worse

Melanin is the skin's way of protecting itself from the sun, and the skin will quickly produce more melanin any time it is exposed to the rays of the sun. This is the simple reason why sun exposure makes acne hyperpigmentation worse. The more sun exposure, the more melanin the skin produces to protect itself.3

Melanin has a remarkable ability to absorb UV rays, and protect your skin from the sun by preventing the sun's rays from damaging DNA and other parts of skin cells. You can see this in action if you spend time in the sun and get a suntan. That extra color comes from extra melanin.

The problem is, with hyperpigmentation, extra melanin is the last thing you need. Dark patches on your skin can become darker, and they can also last longer.

Inflammation from acne lesions can lead to more melanin

How to Treat Acne Hyperpigmentation

Because hyperpigmentation gets worse in the sun, one way to make sure that it fades as quickly as possible is to avoid direct sun exposure, and keep any skin with acne hyperpigmentation out of the sun through protective clothing or hats and by sunscreen whenever the skin is directly exposed to the sun.4 Dermatologists recommend broad-spectrum sunscreens with SPF values of 15 or higher.5

Protect Yourself From The Sun in Two Ways

Once you have your skin protected from the sun, there are topical treatments that you can apply to your skin that can help quicken the fading of hyperpigmentation, including:5,6

Some of these are bleaching agents that prevent melanin production, while others encourage cells to turn over faster so you shed the ones with the extra melanin more quickly.

The Bottom Line

If you tend to have red or dark marks that linger after acne lesions heal, firstly and most importantly, you want to clear your acne to prevent future battles with this kind of lingering hyperpigmentation. However, to ensure that these marks fade as quickly as possible, is also important to keep hyperpigmented skin out of the sun or wear broad-spectrum sunscreen to help the marks fade more quickly.

References:

  1. Stulberg, D. L., Clark, N. & Tovey, D. Common hyperpigmentation disorders in adults: Part I. Diagnostic approach, café au lait macules, diffuse hyperpigmentation, sun exposure, and phototoxic reactions. Am Fam Phys 68, 1955 - 60 (2003).
  2. Stulberg, D. L., Clark, N. & Tovey, D. Common hyperpigmentation disorders in adults: Part II. Melanoma, seborrheic keratoses, acanthosis nigricans, melasma, diabetic dermopathy, tinea versicolor, and post-inflammatory hyperpigmentation. Am Fam Phys 68, 1963 - 8 (2003).
  3. Potrądzikowa, H., Przegląd, K., Kishan, H., Yadalla, K. & Aradhya, S. Post acne hyperpigmentation: A brief review. Our Dermatol Online 2, 230 - 231 (2011).
  4. Chandra, M., Levitt, J. & Pensabene, C. A. Hydroquinone therapy for post-inflammatory hyperpigmentation secondary to acne: not just prescribable by dermatologists. Acta Derm Venereol 92, 232 - 5 (2012).
  5. Trivedi, M. K., Yang, F. C. & Cho, B. K. A review of laser and light therapy in melasma. Int J Womens Dermatol 3, 11 - 20 (2017).
  6. Lynde, C. B., Kraft, J. N. & Lynde, C. W. Topical treatments for melasma and post-inflammatory hyperpigmentation. Skin Therapy Lett 11, 1 - 6 (2006).

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