Editing Acne (section)

===Pigmentation===
After an inflamed nodular acne lesion resolves, it is common for [[Postinflammatory hyperpigmentation|the skin to darken]] in that area, which is known as [[postinflammatory hyperpigmentation]] (PIH). The inflammation stimulates specialized pigment-producing skin cells (known as [[melanocyte]]s) to produce more [[melanin]] pigment, which leads to the skin's darkened appearance.<ref name="Chandra2012"/> PIH occurs more frequently in people with [[Fitzpatrick scale|darker skin color]].<ref name=Yin2014/> Pigmented scar is a common term used for PIH, but is misleading as it suggests the color change is permanent. Often, PIH can be prevented by avoiding any aggravation of the nodule and can fade with time. However, untreated PIH can last for months, years, or even be permanent if deeper layers of skin are affected.<ref name="Callender2011">{{cite journal | vauthors = Callender VD, St Surin-Lord S, Davis EC, Maclin M | title = Postinflammatory hyperpigmentation: etiologic and therapeutic considerations | journal = American Journal of Clinical Dermatology | volume = 12 | issue = 2 | pages = 87–99 | date = April 2011 | pmid = 21348540 | doi = 10.2165/11536930-000000000-00000 | s2cid = 9997519 | type = Review }}</ref> Even minimal skin exposure to the sun's [[ultraviolet radiation|ultraviolet rays]] can sustain hyperpigmentation.<ref name="Chandra2012">{{cite journal | vauthors = Chandra M, Levitt J, Pensabene CA | title = Hydroquinone therapy for post-inflammatory hyperpigmentation secondary to acne: not just prescribable by dermatologists | journal = Acta Dermato-Venereologica | volume = 92 | issue = 3 | pages = 232–5 | date = May 2012 | pmid = 22002814 | doi = 10.2340/00015555-1225 | type = Review | doi-access = free }}</ref> Daily use of [[Sun protection factor|SPF]]&nbsp;15 or higher [[sunscreen]] can minimize such a risk.<ref name="Callender2011" /> Whitening agents like [[azelaic acid]], [[arbutin]] or else may be used to improve hyperpigmentation.<ref>{{cite journal |last1=Liyanage |first1=Achala |last2=Liyanage |first2=Gayani |last3=Sirimanna |first3=Ganga |last4=Schürer |first4=Nanna |date=February 2022 |title=Comparative Study on Depigmenting Agents in Skin of Color |journal=The Journal of Clinical and Aesthetic Dermatology |volume=15 |issue=2 |pages=12–17 |issn=1941-2789 |pmc=8884189 |pmid=35309879}}</ref>