What is post-inflammatory erythema?
Post-inflammatory erythema (PIE) is pink or red marks that are left on your skin following acne or an injury. PIE usually affects people with lighter skin. The marks may fade over time.
People with darker skin are more likely to develop a similar type of condition, called post-inflammatory hyperpigmentation (PIH). These marks may be brown, gray, or darker than your natural skin tone.
Both PIE and PIH are harmless. But the marks can be noticeable and make you feel self-conscious.
Why do some people get dark spots after acne?
The inflammation from acne can dilate (widen) or damage capillaries in the affected area, leading to PIE, which is basically redness.
PIH is also caused by inflammation or trauma to your skin. But rather than affecting the capillaries, the inflammation or trauma triggers the over-production of melanin, which is your natural skin pigment.
PIH spots may fade on their own, but this process can take longer compared to PIE because pigment takes longer to fade.
The great news is that post inflammatory erythema will fade over time on its own. It usually takes anywhere from 4 to 8 weeks for a complete resolution. With treatment, PIE will fade faster. Even if you do not treat the PIE, wearing sunscreen is important. The sun makes them worse. And the treatments can make you more likely to burn. —Dr. Lauren Levy
How to prevent dark spots from acne
The best way to prevent PIE and PIH is to treat your acne and avoid picking at it. Over-the-counter (OTC) products such as retinols and acne-fighting cleansers and moisturizers may be recommended. But if your acne is stubborn or severe, you may need to see a dermatologist, who will prescribe medications to treat it.
Using sunscreen daily is also a must because sun exposure can darken the marks and make them even more noticeable. Sun exposure can also make PIE last longer.
An important question to ask your doctor is, for how long should I use the medication? Some lightning agents can only be used for 12 to 16 weeks at a time before taking a break. This is true for hydroquinone. Avoid side effects by making sure you understand and know the length of the treatment course your doctor wants you to have. —Dr. Levy
Do over-the-counter treatments work?
There are several different medications and natural therapies that may help fade PIE and PIH marks. Some of them are just available over the counter, but some are also available in higher strengths by prescription. Some OTC and prescription creams combine a number of ingredients for a more effective approach (Skinceuticals discoloration defense; SkinMedica Lytera 2.0). But before you try any of them, ask your doctor about what types of treatments would be the safest and most effective for you.
Prescription versions are often compounded together by a pharmacist.
How to fade post inflammatory erythema
Many treatments for PIE and PIH work by inhibiting tyrosinase, which is an enzyme that’s crucial for melanin pigment to be made. Some also contain other ingredients.
Hydroquinone works by inhibiting tyrosinase. It is available as an OTC or prescription cream. You should not use either type for long periods of time as it can cause a condition called ochronosis, which leads to deposits of the medication in the skin and can worsen pigmentation.
Retinoids inhibit the process of producing and storing pigment in skin cells (called melanosome transfer). Retinoids also speed cell turnover, which decreases pigment in skin cells. The most effective retinoids are prescription medications, such as tretinoin. OTC retinols can be used but are less potent and usually less effective than prescription versions.
Azelaic acid also inhibits tyrosinase, making it effective for PIH. It also acts as an anti-inflammatory, which can help with PIE. It can be found OTC or as part of a prescription compounded medication. A study in Clinical Therapeutics using 20% azelaic acid in darker skinned people found an improvement in PIH after 24 weeks of treatment compared to placebo.
This acid comes from a mushroom and inhibits tyrosinase to help fade dark marks and even out skin tone. It is available over the counter or in a prescription compounded medication.
Licorice root extract
Licorice root extract is a natural product that works by both inhibiting tyrosinase and removing melanin. It is found in many OTC skin-lightening products and has very few side effects. It also has anti-inflammatory properties and can help treat active acne lesions, an added benefit.
Arbutin is a naturally occurring derivative of hydroquinone. In addition to inhibiting tyrosinase, arbutin slows the development of melanosomes, which produce pigment. It is found in many OTC serums.
It’s thought to be less effective than Kojic acid, according to a review in the Journal of Cutaneous and Aesthetic Surgery. Higher concentrations are more effective at skin lightening, but these higher concentrations may have the opposite effect of skin darkening in some people.
When used in a cream, resorcinol can lead to rapid skin lightening. It is a more powerful inhibitor of tyrosinase than hydroquinone, kojic acid, and arbutin, and has only minimal skin irritation.
Tranexamic acid is available in topical (applied to the skin) or oral forms. It’s thought to work by decreasing melanin overproduction from sun exposure. The topical version can be found in many OTC lightening agents or can be in a prescription compound medication.
The oral treatment requires a prescription and close monitoring. This medication is usually used to slow or stop bleeding, so your doctor may not recommend it if you have certain bleeding disorders or are prone to blood clots.
A steroid may be included in some combination creams because it has anti-inflammatory effects. But only prescription strength steroids are strong enough to help lighten the skin. You want to avoid using a topical steroid on the face for prolonged periods of time as it can cause acne, rosacea, and skin thinning.
Antioxidants that can help PIE
Vitamin C is an antioxidant found in many OTC antiaging, skin brightening, and skin fading creams and serum. It works by reducing a substance called dopaquinone, which is needed to produce melanin. It has anti-inflammatory properties and can help protect skin from UV rays. It is safe to use in all skin types and can be used over the long term.
Ferulic acid is an antioxidant but also makes other antioxidants more effective (like vitamin C). It is in many skin care and skin-lightening products.
Nicotinamide (or niacinamide) is also known as vitamin B3. It has antioxidant properties and also decreases melanosome transfer. It can help with skin lightening and reduce inflammation.
Soy contains enzymes that have anti-aging and antioxidant properties. It also inhibits melanosome transfer.
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Your doctor uses a device that delivers light energy to target and destroy PIH marks. While studies show that laser therapy can be effective, there is a chance it could worsen PIH. Studies are examining whether combining tranexamic acid with laser therapy is more effective.
PIE can be treated with pulsed dye laser therapy, which targets blood vessels. It’s been shown to reduce the redness of PIE.
Laser therapy can be uncomfortable. Some patients say the sensation feels like a hot rubber band striking the skin. Sometimes, a topical numbing cream can be applied before treatment to help with the discomfort.
Laser therapy can also cause mild redness and irritation of the skin, but these symptoms go away shortly after treatment. You’ll need to wear eye protection during the session because laser therapy can damage your eyes.
Ask your doctor about blue light or red light treatment. A simple in-office procedure—sitting under specialized lamps—can help reduce redness and inflammation of the skin. Many dermatology, plastic surgeons, and medi spas offer this simple and effective treatment. —Dr. Levy
Microneedling involves pricking the skin with very tiny needles, which stimulates your body’s healing process. It can be used in combination with topical medications, like Vitamin C or Tranexamic acid, to further help reduce PIE and PIH. Risks of microneedling include new PIH and redness.
Certain types of chemicals are able to peel away the top levels of your skin. This lightens and reduces pigment in skin, and speeds up the skin growth cycle. Chemical peels vary in strength from mild to deep. Because deeper peels can sometimes cause PIH, it’s safer to start with more superficial peels.
Side effects of chemical peels include a burning sensation and temporary redness of your skin. After several minutes, the peel is neutralized by washing away the chemicals or applying a second chemical. Examples of superficial peels include glycolic acid (an alpha-hydroxy acid), salicylic acid (a beta-hydroxy acid), Jessner’s solution, and trichloroacetic acid.
Cover-ups for PIE
Some people choose to use makeup to cover PIE or PIH marks. Just make sure the label says “non-comedogenic,” which means it won’t cause acne or worsen existing pimples. It’s better to use both sunscreen and facial makeup instead of using one or the other (even if the makeup contains SPF sunscreen). The combination is more effective at protecting your skin from UV rays, according to a study in Skin Research & Technology. This will help PIE or PIH from getting worse.
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