Editing Acne (section)

===Procedures===
Limited evidence supports [[comedo extraction]], but it is an option for comedones that do not improve with standard treatment.<ref name=Titus2012/><ref name="Zaenglein2016"/> Another procedure for immediate relief is the injection of a corticosteroid into an inflamed acne comedo.<ref name="Zaenglein2016"/> [[Electrocautery]] and [[electrofulguration]] are effective alternative treatments for comedones.<ref>{{cite book| vauthors = Bolognia JL, Jorizzo JL |title=Dermatology |date=2012 |publisher=Mosby Elsevier|location=St. Louis, Mo. |isbn=9780702051821 |edition=3rd |page=558}}</ref>

[[Light therapy]] is a treatment method that involves delivering certain specific wavelengths of light to an area of skin affected by acne. Both regular and [[laser light]] have been used. The evidence for [[light therapy]] as a treatment for acne is weak and inconclusive.<ref name="Titus2012"/><ref name="Posadzki2018">{{cite journal | vauthors = Posadzki P, Car J | title = Light Therapies for Acne | journal = JAMA Dermatology | volume = 154 | issue = 5 | pages = 597–598 | date = May 2018 | pmid = 29541753 | doi = 10.1001/jamadermatol.2018.0110 }}</ref> Various light therapies appear to provide a short-term benefit, but data for long-term outcomes, and outcomes in those with severe acne, are sparse;<ref name="Hamil2009">{{cite journal | vauthors = Hamilton FL, Car J, Lyons C, Car M, Layton A, Majeed A | title = Laser and other light therapies for the treatment of acne vulgaris: systematic review | journal = The British Journal of Dermatology | volume = 160 | issue = 6 | pages = 1273–85 | date = June 2009 | pmid = 19239470 | doi = 10.1111/j.1365-2133.2009.09047.x | s2cid = 6902995 | type = Systematic Review & Meta-Analysis }}</ref> it may have a role for individuals whose acne has been resistant to topical medications.<ref name="Aslam2015" /> A 2016 meta-analysis was unable to conclude whether light therapies were more beneficial than placebo or no treatment, nor the duration of benefit.<ref>{{cite journal | vauthors = Barbaric J, Abbott R, Posadzki P, Car M, Gunn LH, Layton AM, Majeed A, Car J | display-authors = 6 | title = Light therapies for acne | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | pages = CD007917 | date = September 2016 | issue = 9 | pmid = 27670126 | pmc = 6457763 | doi = 10.1002/14651858.CD007917.pub2 }}</ref>

When regular light is used immediately following the application of a [[photosensitizer|sensitizing substance]] to the skin such as [[aminolevulinic acid]] or [[methyl aminolevulinate]], the treatment is referred to as [[photodynamic therapy]] (PDT).<ref name="Barbieri2019"/><ref name="Pugashetti2013">{{cite journal | vauthors = Pugashetti R, Shinkai K | title = Treatment of acne vulgaris in pregnant patients | journal = Dermatologic Therapy | volume = 26 | issue = 4 | pages = 302–11 | date = July 2013 | pmid = 23914887 | doi = 10.1111/dth.12077 | s2cid = 5750718 | type = Review | doi-access = free }}</ref> PDT has the most supporting evidence of all light therapy modalities.<ref name="Zaenglein2016" /> PDT treats acne by using various forms of light (e.g., blue light or red light) that preferentially target the pilosebaceous unit.<ref name="Barbieri2019"/> Once the light activates the sensitizing substance, this generates [[free radicals]] and [[reactive oxygen species]] in the skin, which purposefully damage the sebaceous glands and kill ''C. acnes'' bacteria.<ref name="Barbieri2019"/> Many different types of nonablative lasers (i.e., lasers that do not vaporize the top layer of the skin but rather induce a physiologic response in the skin from the light) have been used to treat acne, including those that use infrared wavelengths of light. Ablative lasers (such as [[Carbon dioxide laser|CO<sub>2</sub>]] and fractional types) have also been used to treat active acne and its scars. When ablative lasers are used, the treatment is often referred to as [[laser resurfacing]] because, as mentioned previously, the entire upper layers of the skin are vaporized.<ref name="Cohen2016"/> Ablative lasers are associated with higher rates of adverse effects compared with non-ablative lasers, with examples being post-inflammatory hyperpigmentation, persistent facial redness, and persistent pain.<ref name=Titus2012/><ref name=Ong2012>{{cite journal | vauthors = Ong MW, Bashir SJ | title = Fractional laser resurfacing for acne scars: a review | journal = The British Journal of Dermatology | volume = 166 | issue = 6 | pages = 1160–9 | date = June 2012 | pmid = 22296284 | doi = 10.1111/j.1365-2133.2012.10870.x | s2cid = 205262673 | type = Review }}</ref><ref name="Abdel2016">{{cite journal | vauthors = Abdel Hay R, Shalaby K, Zaher H, Hafez V, Chi CC, Dimitri S, Nabhan AF, Layton AM | display-authors = 6 | title = Interventions for acne scars | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | pages = CD011946 | date = April 2016 | issue = 4 | pmid = 27038134 | doi = 10.1002/14651858.CD011946.pub2 | type = Systematic Review & Meta-Analysis | pmc = 7069546 }}</ref> Physiologically, certain wavelengths of light, used with or without accompanying topical chemicals, are thought to kill bacteria and decrease the size and activity of the glands that produce sebum.<ref name="Pugashetti2013"/> Disadvantages of light therapy can include its cost, the need for multiple visits, the time required to complete the procedure(s), and pain associated with some of the treatment modalities.<ref name="Aslam2015"/> Typical side effects include [[desquamation|skin peeling]], temporary reddening of the skin, swelling, and post-inflammatory hyperpigmentation.<ref name="Aslam2015" />

====Postacne scar treatment====
[[Dermabrasion]] is an effective therapeutic procedure for reducing the appearance of superficial atrophic scars of the boxcar and rolling varieties.<ref name="Levy2012"/> Ice-pick scars do not respond well to treatment with dermabrasion due to their depth.<ref name="Levy2012"/> The procedure is painful and has many potential side effects such as skin sensitivity to sunlight, [[erythema|redness]], and [[Hypopigmentation|decreased pigmentation of the skin]].<ref name="Levy2012"/> Dermabrasion has fallen out of favor with the introduction of laser resurfacing.<ref name="Levy2012"/> Unlike dermabrasion, there is no evidence that [[microdermabrasion]] is an effective treatment for acne.<ref name="Titus2012"/>

Dermal or subcutaneous [[Injectable filler|filler]]s are substances injected into the skin to improve the appearance of acne scars. Fillers are used to increase natural [[collagen]] production in the skin and to increase skin volume and decrease the depth of acne scars.<ref name="Soliman2018">{{cite journal | vauthors = Soliman YS, Horowitz R, Hashim PW, Nia JK, Farberg AS, Goldenberg G | title = Update on acne scar treatment | journal = Cutis | volume = 102 | issue = 1 | pages = 21;25;47;48 | date = July 2018 | pmid = 30138491 | url = https://www.mdedge.com/cutis/article/169785/acne/update-acne-scar-treatment | type = Review | access-date = 19 September 2018 | archive-url = https://web.archive.org/web/20180919132148/https://www.mdedge.com/cutis/article/169785/acne/update-acne-scar-treatment | archive-date = 19 September 2018 | url-status = live }}</ref> Examples of fillers used for this purpose include [[hyaluronic acid]]; [[poly(methyl methacrylate)]] [[microsphere]]s with collagen; human and bovine collagen derivatives, and fat harvested from the person's own body (autologous fat transfer).<ref name="Soliman2018"/>

[[Microneedling]] is a procedure in which an instrument with multiple rows of tiny needles is rolled over the skin to elicit a wound healing response and stimulate collagen production to reduce the appearance of atrophic acne scars in people with darker skin color.<ref name="Cohen2016">{{cite journal | vauthors = Cohen BE, Elbuluk N | title = Microneedling in skin of color: A review of uses and efficacy | journal = Journal of the American Academy of Dermatology | volume = 74 | issue = 2 | pages = 348–55 | date = February 2016 | pmid = 26549251 | doi = 10.1016/j.jaad.2015.09.024 | type = Review }}</ref> Notable adverse effects of microneedling include post-inflammatory hyperpigmentation and tram track scarring (described as discrete slightly raised scars in a linear distribution similar to a tram track). The latter is thought to be primarily attributable to improper technique by the practitioner, including the use of excessive pressure or inappropriately large needles.<ref name="Cohen2016"/><ref name="Pahwa2012">{{cite journal | vauthors = Pahwa M, Pahwa P, Zaheer A | title = "Tram track effect" after treatment of acne scars using a microneedling device | journal = Dermatologic Surgery | volume = 38 | issue = 7 Pt 1 | pages = 1107–8 | date = July 2012 | pmid = 22587597 | doi = 10.1111/j.1524-4725.2012.02441.x | type = Case Report & Literature Review }}</ref>

A clinical study assessing the efficacy of microneedling vis-à-vis with application of topical [[tazarotene]] gel, 0.1% in the treatment of postacne facial scars, found that tazarotene gel when applied for a period of three to six months once every night, resulted in significant improvement of atrophic scars similar to microneedling.<ref name="Tazarotene">{{cite journal |last1=Afra |first1=TP |last2=Razmi |first2=T M |last3=Narang |first3=T |last4=Dogra |first4=S |last5=Kumar |first5=A |title=Topical Tazarotene Gel, 0.1%, as a Novel Treatment Approach for Atrophic Postacne Scars: A Randomized Active-Controlled Clinical Trial |journal=JAMA Facial Plast Surg |date=2019 |volume=21 |issue=2 |pages=125–132 |doi=10.1001/jamafacial.2018.1404 |pmid=30452511|pmc=6439800 }}</ref>

[[Subcision]] is useful for the treatment of superficial atrophic acne scars and involves the use of a small needle to loosen the fibrotic adhesions that result in the depressed appearance of the scar.<ref>{{cite journal | vauthors = Lanoue J, Goldenberg G | title = Acne scarring: a review of cosmetic therapies | journal = Cutis | volume = 95 | issue = 5 | pages = 276–81 | date = May 2015 | pmid = 26057505 | type = Review }}</ref><ref>{{cite journal | vauthors = Kroepfl L, Emer JJ | title = Combination Therapy for Acne Scarring: Personal Experience and Clinical Suggestions | journal = Journal of Drugs in Dermatology | volume = 15 | issue = 11 | pages = 1413–1419 | date = November 2016 | pmid = 28095556 | type = Review }}</ref><ref>{{cite journal | vauthors = Zaleski-Larsen LA, Fabi SG, McGraw T, Taylor M | title = Acne Scar Treatment: A Multimodality Approach Tailored to Scar Type | journal = Dermatologic Surgery | volume = 42 Suppl 2 | issue = Supplement 2 | pages = S139-49 | date = May 2016 | pmid = 27128240 | doi = 10.1097/DSS.0000000000000746 | s2cid = 25638674 | type = Review }}</ref>

[[Chemical peel]]s can be used to reduce the appearance of acne scars.<ref name=Levy2012/> Mild peels include those using [[glycolic acid]], [[lactic acid]], [[salicylic acid]], [[Jessner's solution]], or a lower concentration (20%) of [[trichloroacetic acid]]. These peels only affect the [[epidermis|epidermal layer of the skin]] and can be useful in the treatment of superficial acne scars as well as skin pigmentation changes from inflammatory acne.<ref name=Levy2012/> Higher concentrations of trichloroacetic acid (30–40%) are considered to be medium-strength peels and affect the skin as deep as the [[Dermis#Stratum papillare|papillary dermis]].<ref name=Levy2012/> Formulations of trichloroacetic acid concentrated to 50% or more are considered to be deep chemical peels.<ref name=Levy2012/> Medium-strength and deep-strength chemical peels are more effective for deeper atrophic scars but are more likely to cause side effects such as skin pigmentation changes, infection, and [[Milium (dermatology)|small white superficial cysts known as milia]].<ref name=Levy2012/>