Post-inflammatory hyperpigmentation (PIH), the dark spots or red spots that are left after acne lesions heal, develops when the inflammation inherent in acne lesions causes skin cells to produce more melanin, which is the pigment that gives skin its color. An increased amount of melanin makes the skin appear darker. These marks are sometimes referred to as “macules” and can last for months or even years in some cases.
Hyperpigmentation is common among people of African, Asian, and Latino descent, as well as other forms of non-Caucasian skin.1-5Hyperpigmentation can also occur in Caucasian skin, albeit less frequently. UV light – the light from the rays of the sun – can make hyperpigmentation worse and cause it to remain longer. However, it is not clear whether UV light worsens acne itself, as research studies have reported that UV radiation can both increase6and decrease7acne. Regardless, for all skin types, it is important to take appropriate steps to protect your skin from excessive sun in order to avoid worsening of hyperpigmentation and allow any hyperpigmentation you currently have to heal as fast as possible.
Various forms of acne therapy, such as lasers and chemical peels are often mistakenly blamed for the creation of hyperpigmented marks, but it is the skin's inflammatory process that creates them.8Although people often call them scars, they are not permanent and will disappear with time. Nonetheless, they can cause intense distress. Often, people with hyperpigmentation describe this issue as more concerning than the acne itself.
How to Prevent Hyperpigmentation
Picking at acne lesions is the worst culprit when it comes to creating hyperpigmentation. Absolutely do not pick at acne lesions. Properly pop a pimple only when it is ready to be popped, and then leave the lesion alone. Also, while it may seem intuitive to scrub marks away, harsh scrubbing will only prolong their duration and should be avoided. Be sure to wash gently. Next, as mentioned, keeping hyperpigmented skin out of the sun when possible is a huge help in allowing these marks to fade as quickly as possible. Wearing a sunscreen is important as well.1,5,9
The best way to prevent hyperpigmentation is to treat the acne itself, thus preventing future acne lesions and any hyperpigmentation that they might leave behind.10Acne is treated the same regardless of skin color and responds extremely well to proper topical treatment with benzoyl peroxide. When acne is severe, widespread, and deeply scarring, Accutane (isotretinoin) is also an option.
How to Treat Hyperpigmentation
First, get your skin completely clear from active acne. This way you are preventing any future hyperpigmentation. Once you are clear, you can try a hyperpigmentation treatment to reduce the marks you might have. Topical treatments are the first choice for treating hyperpigmentation. The treatments most commonly prescribed by dermatologists are hydroquinone (HQ) and retinoids.11
Hydroquinone (Bleach Eze®) is the first choice of treatment for hyperpigmentation.12It is normally used at a concentration of 4%. In higher concentrations it can cause "spotted halos," which appear as lighter colored ring around marks. Hydroquinone treatment results in a marked improvement or complete clearing of PIH in 63% of the patients.4The efficacy of hydroquinone may be increased by the addition of a retinoid and a low potency corticosteroid, such as hydrocortisone.13Side effects of hydroquinone include burning, redness, and itching in 30% of the patients.12The addition of ascorbic acid (Vitamin C) to a topical hydroquinone treatment may help minimize side effects.2-3Hyperpigmentation starts to subside after 4 weeks of hydroquinone treatment, but maximum results usually require 8 to 12 weeks of treatment. Be certain to work closely with your physician or dermatologist if you decide to use hydroquinone to ensure proper dosage and reduction of side effects.
Retinoids: Tretinoin (Retin-A®), Adapalene (Differin®), or Tazarotene (Tazorac®). Retinoids are vitamin A analogues that are typically used together with hydroquinone. Retinoids are topical treatments that can help fade marks and treat acne at the same time.
According to the Journal of the American Academy of Dermatology, “Of particular significance to skin of color patients is the ability of retinoids to treat both acne and PIH. By increasing epidermal turnover, these agents facilitate melanin dispersion and removal.”8
A study published in The New England Journal of Medicine on people with skin that was darkened by hyperpigmentation showed that daily retinoid treatment resulted in “much lighter” skin in 53% of participants and in “somewhat lighter” skin in an additional 33% of patients.14
If retinoids are used alone and not in combination with hydroquinone, dermatologists often prescribe a topical corticosteroid in order to reduce the irritation and potential worsening of PIH that retinoids can cause when they are used alone. An expert opinion in Skin Therapy Letters sums it up: “The use of retinoids as monotherapy is not recommended as an irritant reaction may cause inflammation that induces paradoxical hyperpigmentation; a similar concern exists over the use of HQ as monotherapy at very high concentrations (i.e., 8-20%).”12
Retinoids typically take 8 to 12 weeks to produce maximum results. The frequency and concentration of retinoid therapy depends on the severity of hyperpigmentation and should be determined by a dermatologist.
Niacinamide, also known as Nicotinamide, is a B vitamin that can be administered topically, and is currently being investigated as a potential therapy for hyperpigmentation.
A study published in the journal Cutis in 2015 showed that a topical cream containing 4% niacinamide in combination with the other pigment-lightening and anti-inflammatory compounds arbutin, bisabolol, and retinaldehyde reduced hyperpigmentation due to melasma by 34% over a period of two months. Melasma is a common skin problem where brown marks appear on the face due to pregnancy or sun exposure.15To date, there exists no published research that has investigated whether niacinamide is also effective in treating PIH, but studies are currently in progress.
Azelaic acid is another topical acne prescription that is sometimes used for PIH that works by slowing down the production of melanin. It is a gel that doctors normally prescribe in 20% concentration for PIH, applied twice a day. Azelaic acid is safe and effective for the treatment of both acne and PIH conditions in darker skin types. Common side effects include mild redness, scaling, and burning.16Due to the mechanism of action of azelaic acid, results are not seen for the first few months of azelaic acid treatment, but results are eventually seen after six months.
Second-line Treatments of Hyperpigmentation
Chemical peels and laser treatments are often employed if topical therapy fails. While these treatments can be effective in treating PIH, they can also worsen hyperpigmentation if used incorrectly. They should therefore be administered by an experienced professional who specializes in PIH.17
Superficial chemical peels, which include salicylic acid, Jessner’s solution, lactic acid, mandelic acid, and glycolic acid cause the fewest side effects and the preferred choice of chemical peels for hyperpigmentation. Peels that penetrate more deeply into the skin, such as TCA peel, Jessner’s/TCA combination peel and phenol, result in more serious side effects such as pain and burning sensations as well as the potential to worsen pigmentation, and are therefore not recommended.1-3,12,18
Gentle Chemical Exfoliation. Over-the-counter glycolic acid products are available in strengths up to 10% and can provide gentler chemical “peeling,” which is better described as gentle chemical exfoliation. At lower percentages in over-the-counter products, glycolic acid does not cause the skin to visibly peel off in sheets like professionally administered chemical peels do, and instead provides exfoliation of only the surface cells of the skin. This is a slower and safer way to achieve the skin turnover required to reduce hyperpigmentation and can be used on a more frequent basis when compared to chemical peels. Most people find that they can tolerate over-the-counter 10% glycolic acid products every two or three nights, or every night when mixed ½ and ½ with moisturizer.
Dry ice cryotherapy. Doctors will sometimes use application of dry ice to help the mark fade.
Lasers. Laser therapy tends to produce results on par with topical treatment.19-20However, the use of lasers to treat hyperpigmentation is controversial because they can worsen hyperpigmentation in some cases.
According to an article in the journal Dermatology Clinics, “Although lasers are reported in many studies to be helpful for the treatment of melasma (and in some instances PIH), in reality, there is a significant limitation to laser-based devices for pigmentation given the risk of rebound pigmentation or worsening, even with conservative treatment.”11In addition, laser therapy can cause the skin to become more sensitive to the sun, necessitating “an intensive brightening, anti-inflammatory, and sun-protective skin care regimen” following treatment.12
Microdermabrasion. Performed at salons and estheticians' offices, microdermabrasion helps remove the upper layers of skin cells. However, results are weak and abrading the skin can cause irritation, which perpetuates the acne cycle. Microdermabrasion should be avoided in acne-prone individuals.2-3
Whichever treatment option(s) you choose, remember that taking preventative steps to limit hyperpigmentation in the first place can go a long way toward getting a handle on this problem. Always wear sunscreen, limit your time in the sun, and avoid picking at the skin. In time, you will see improvements in the appearance of your skin.