Editing Hyperpigmentation (section)

===Topical treatments===
Many topical treatments disrupt the synthesis of melanin by inhibiting the enzyme [[tyrosine hydroxylase]].<ref name="Kim Kang 2015 pp. 607–612"/>

Several are prescription only in the US, especially in high doses, such as [[hydroquinone]], [[azelaic acid]],<ref>{{Cite journal|last1=Mazurek|first1=Klaudia|last2=Pierzchała|first2=Ewa|date=2016-09-01|title=Comparison of efficacy of products containing azelaic acid in melasma treatment|journal=Journal of Cosmetic Dermatology|volume=15|issue=3|pages=269–282|doi=10.1111/jocd.12217|issn=1473-2165|pmid=27028014|s2cid=25303091}}</ref> and [[kojic acid]].<ref>{{Cite journal|last1=Monteiro|first1=Rochelle C.|last2=Kishore|first2=B. Nanda|last3=Bhat|first3=Ramesh M.|last4=Sukumar|first4=D.|last5=Martis|first5=Jacintha|last6=Ganesh|first6=H. Kamath|date=2013-03-01|title=A Comparative Study of the Efficacy of 4% Hydroquinone vs 0.75% Kojic Acid Cream in the Treatment of Facial Melasma|journal=Indian Journal of Dermatology|volume=58|issue=2|pages=157|doi=10.4103/0019-5154.108070|issn=1998-3611|pmc=3657227|pmid=23716817 |doi-access=free }}</ref> Some are available without prescription, such as [[niacinamide]],<ref>{{Cite journal|last1=Hakozaki|first1=T.|last2=Minwalla|first2=L.|last3=Zhuang|first3=J.|last4=Chhoa|first4=M.|last5=Matsubara|first5=A.|last6=Miyamoto|first6=K.|last7=Greatens|first7=A.|last8=Hillebrand|first8=G.G.|last9=Bissett|first9=D.L.|date=2002-07-01|title=The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer|journal=British Journal of Dermatology|volume=147|issue=1|pages=20–31|doi=10.1046/j.1365-2133.2002.04834.x|pmid=12100180|s2cid=39489580}}</ref><ref>{{Cite news|url=https://www.futurederm.com/spotlight-on-niacinamide/|title=Spotlight On: Niacinamide - FutureDerm|date=2007-10-30|newspaper=FutureDerm|access-date=2017-02-12|language=en-US}}</ref> {{sm|l}}-[[ascorbic acid]],{{cn|date=March 2022}} retinoids such as [[tretinoin]],<ref name="Callender Baldwin Cook-Bolden Alexis pp. 69–81">{{cite journal |last1=Callender |first1=Valerie D. |last2=Baldwin |first2=Hilary |last3=Cook-Bolden |first3=Fran E. |last4=Alexis |first4=Andrew F. |last5=Stein Gold |first5=Linda |last6=Guenin |first6=Eric |date=2021-11-09 |title=Effects of Topical Retinoids on Acne and Post-inflammatory Hyperpigmentation in Patients with Skin of Color: A Clinical Review and Implications for Practice |journal=American Journal of Clinical Dermatology |publisher=Springer Science and Business Media LLC |volume=23 |issue=1 |pages=69–81 |doi=10.1007/s40257-021-00643-2 |issn=1175-0561 |pmc=8776661 |pmid=34751927}}</ref> or [[cysteamine hydrochloride]].<ref>{{Cite journal|last1=Mansouri|first1=P.|last2=Farshi|first2=S.|last3=Hashemi|first3=Z.|last4=Kasraee|first4=B.|date=2015-07-01|title=Evaluation of the efficacy of cysteamine 5% cream in the treatment of epidermal melasma: a randomized double-blind placebo-controlled trial|journal=The British Journal of Dermatology|volume=173|issue=1|pages=209–217|doi=10.1111/bjd.13424|issn=1365-2133|pmid=25251767|s2cid=21618233}}</ref><ref>{{Cite news|url=http://www.scientispharma.ch/product/cysteamine-cream/|title=Cysteamine Cream® -- New Hyper Intensive Depigmenting Treatment|newspaper=Scientis Pharma|access-date=2017-02-12|language=en-US|archive-date=2016-12-24|archive-url=https://web.archive.org/web/20161224031421/http://www.scientispharma.ch/product/cysteamine-cream/|url-status=dead}}</ref> Hydroquinone was the most commonly prescribed hyperpigmentation treatment before the long-term safety concerns were raised,<ref>{{Cite journal|last=Draelos|first=Zoe Diana|date=2007-09-01|title=Skin lightening preparations and the hydroquinone controversy|journal=Dermatologic Therapy|volume=20|issue=5|pages=308–313|doi=10.1111/j.1529-8019.2007.00144.x|issn=1529-8019|pmid=18045355|s2cid=24913995|doi-access=free}}</ref> and the use of it became more regulated in several countries and discouraged in general by [[World Health Organization|WHO]].<ref>{{Cite book|title=Hyrdoquinone Guidance published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organisation, and the World Health Organization|hdl = 10665/39218|isbn = 9789241571579|publisher = World Health Organization|year = 1994}}</ref> For the US, only 2% is at present sold over-the-counter, and 4% needs prescription. In the EU hydroquinone was banned from cosmetic applications.<ref>{{Cite web|url=https://echa.europa.eu/information-on-chemicals/evaluation/community-rolling-action-plan/corap-table/-/dislist/details/0b0236e1807e3dff|title=Hydroquinone - Substance evaluation - CoRAP - ECHA|website=echa.europa.eu|language=en-GB|access-date=2017-02-12}}</ref>