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BooksVol. 10Available

Is Your Skincare Worth the Money?

Three Products Earn Their Place. The Rest Is Optional.

by An Thanh Tùng

Kindle edition Paperback

ASIN B0HN46MYLB · B0HN45Z6S1

About this book

A cheap sunscreen applied generously every day beats an expensive one applied sparingly.Chapter 4

A plain-language, evidence-labeled guide to which skincare products are worth the money, which depend on you, which you can skip, and when to see a dermatologist.

What you'll learn

  1. Ch. 1Only three jars have the evidencePay for sunscreen, a retinoid and a moisturizer first. Everything else is optional.
  2. Ch. 2Skin is built to keep things outThe best money goes on what protects it, not on what promises to “penetrate deep.”
  3. Ch. 5The best retinoidIs the strongest one you can tolerate and afford for years, not the newest one on the shelf.
  4. Ch. 8No pill replaces sunscreenCollagen drinks and beauty pills come last: spend on what goes on your skin first.
  5. Ch. 10Acne isn't caused by dirtBenzoyl peroxide and a retinoid, used consistently for 12 weeks, do more than any extra wash.
  6. Ch. 13Don't pay a jar to do a needle's jobCreams work at the surface. Muscle lines and sagging live deeper.

How the book is organized

  1. Part IBefore You Buy
  2. Part IIWhat's Worth Paying For
  3. Part IIIWhen Skin Has a Problem
  4. Part IVYour Plan

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  • Worksheet 12-Week Product Trial Diary 2 pages · Ch. 1 · PDF 46 KB Get the PDF
  • Worksheet Shelf Audit Worksheet 2 pages · Ch. 1, 2, 14 · PDF 40 KB Get the PDF
  • Worksheet The One-Active Worksheet 2 pages · Ch. 3, 7 · PDF 23 KB Get the PDF
  • Worksheet Your 12-Week Plan 2 pages · Ch. 14 · PDF 39 KB Get the PDF
  • Worksheet Before You See a Dermatologist: A Checklist 4 pages · PDF 60 KB Get the PDF
  • Safety card Safety Flags at a Glance 2 pages · PDF 26 KB Get the PDF
  • Reference table If You Notice… Read… 2 pages · PDF 35 KB Get the PDF
  • Reference table Ingredient Dictionary 4 pages · Ch. 5 · PDF 46 KB Get the PDF

111 references

Notes and sources

All sources
Ch. 1Is Your Skincare Worth the Money?7
  1. Daily sunscreen and skin aging Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Ann Intern Med 2013;158(11):781–790. doi:10.7326/0003-4819-158-11-201306040-00002. PMID 23732711.
  2. Topical tretinoin for photoaging Sitohang IBS, Makes WI, Sandora N, Suryanegara J. Topical tretinoin for treating photoaging: a systematic review of randomized controlled trials. Int J Womens Dermatol 2022;8(1):e003. doi:10.1097/JW9.0000000000000003. PMID 35620028. PMC9112391.
  3. Tretinoin studied since the 1980s Weiss JS, Ellis CN, Headington JT, et al. Topical tretinoin improves photoaged skin: a double-blind vehicle-controlled study. JAMA 1988;259(4):527–532. Search PubMed
  4. Moisturizers for dryness and eczema van Zuuren EJ, Fedorowicz Z, Christensen R, Lavrijsen A, Arents BWM. Emollients and moisturisers for eczema. Cochrane Database Syst Rev 2017;2:CD012119. doi:10.1002/14651858.CD012119.pub2. PMID 28166390.
  5. Sunscreen price and protection Mundada M, Schneider J, Wei ML. Sunscreen costs in association with sun protective behaviors. JAMA Dermatol 2026;162(4):402–405. doi:10.1001/jamadermatol.2025.6150. Also: Xu S, Kwa M, Agarwal A, Rademaker A, Kundu RV. Sunscreen product performance and other determinants of consumer preferences. JAMA Dermatol 2016.
  6. Vehicle (base cream) effect Watson REB, Ogden S, Cotterell LF, et al. A cosmetic "anti-ageing" product improves photoaged skin: a double-blind, randomized controlled trial. Br J Dermatol 2009;161(2):419–426. Search PubMed
  7. Retinoids and pregnancy See Chapters 5 and 10.
Ch. 2What Does Your Skin Actually Do?8
  1. Epidermal turnover Weinstein GD, Van Scott EJ. Autoradiographic analysis of turnover times of normal and psoriatic epidermis. J Invest Dermatol 1965;45(4):257–262, PMID 5837896; age-related transit times from data by Kligman.
  2. The 500-dalton rule Bos JD, Meinardi MM. The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Exp Dermatol 2000;9(3):165–169. PMID 10839713.
  3. Collagen and skin thickness after menopause Brincat M, et al. A study of the decrease of skin collagen content, skin thickness, and bone mass in the postmenopausal woman. Obstet Gynecol 1987. PMID 3120067.
  4. Sun and visible facial aging Flament F, Bazin R, Laquieze S, Rubert V, Simonpietri E, Piot B. Effect of the sun on visible clinical signs of aging in Caucasian skin. Clin Cosmet Investig Dermatol 2013;6:221–232. doi:10.2147/CCID.S44686. PMID 24101874. PMC3790843.
  5. Smoking, sun and twins Guyuron B, Rowe DJ, Weinfeld AB, et al. Factors contributing to the facial aging of identical twins. Plast Reconstr Surg 2009;123(4):1321–1331. PMID 19337100.
  6. Melanin as a filter Kaidbey KH, Agin PP, Sayre RM, Kligman AM. Photoprotection by melanin: a comparison of black and Caucasian skin. J Am Acad Dermatol 1979;1(3):249–260. doi:10.1016/s0190-9622(79)70018-170018-1). PMID 512075.
  7. Skin color and UV damage Fajuyigbe D, Young AR. The impact of skin colour on human photobiological responses. Pigment Cell Melanoma Res 2016. PMC5132026.
  8. Probiotic cosmetics Theodorou IM, Kapoukranidou D, Theodorou M, et al. Cosmeceuticals: a review of clinical studies claiming to contain specific, well-characterized strains of probiotics or postbiotics. Nutrients 2024;16(15):2526. doi:10.3390/nu16152526. PMC11314542.
Ch. 3Reading the Label and the Ad10
  1. "Hypoallergenic" claims US Food and Drug Administration. Hypoallergenic cosmetics (consumer information). Almay, Inc. v. Califano, US Court of Appeals for the D.C. Circuit, 1977.
  2. US cosmetics law US Food and Drug Administration. Modernization of Cosmetics Regulation Act of 2022 (MoCRA).
  3. EU claims rules Commission Regulation (EU) No 655/2013 laying down common criteria for the justification of claims used in relation to cosmetic products; Regulation (EC) No 1223/2009 on cosmetic products.
  4. Filters in beauty ads Advertising Standards Authority (UK). Rulings on Tanologist Tan (We Are Luxe Ltd) and Skinny Tan, February 2021.
  5. Ingredient list order Regulation (EC) No 1223/2009, Article 19; US Code of Federal Regulations, 21 CFR 701.3.
  6. Phenoxyethanol limit Regulation (EC) No 1223/2009, Annex V.
  7. Allergens in "natural" and "clean" products Young PA, Gui H, Bae GH. Prevalence of contact allergens in natural skin care products from US commercial retailers. JAMA Dermatol 2022 (published online September 14, 2022). PMC9475434.
  8. Fragrance as the leading cosmetic allergen Johansen JD. Fragrance contact allergy: a clinical review. Am J Clin Dermatol 2003;4(11):789–798. PMID 14572300. Systematic review of patch testing with cosmetics, 2024. PMC11334351.
  9. Parabens and breast cancer Darbre PD, Aljarrah A, Miller WR, et al. Concentrations of parabens in human breast tumours. J Appl Toxicol 2004;24(1):5–13. Scientific Committee on Consumer Products (SCCP), opinion on parabens and breast cancer, 2005; Scientific Committee on Consumer Safety (SCCS), opinions on parabens, 2010–2013. Search PubMed
  10. Methylisothiazolinone Commission Regulation (EU) 2016/1198.
Ch. 4Sunscreen: The Cheapest Anti-Aging Product13
  1. Skin aging Hughes et al. 2013 (see Chapter 1).
  2. Squamous cell carcinoma Green A, Williams G, Neale R, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial. Lancet 1999;354(9180):723–729. Search PubMed
  3. Melanoma Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. J Clin Oncol 2011;29(3):257–263. Search PubMed
  4. Sunscreen ingredients in the blood Matta MK, Zusterzeel R, Pilli NR, et al. JAMA 2019;321(21):2082–2091. Matta MK, Florian J, Zusterzeel R, et al. JAMA 2020;323(3):256–267.
  5. US sunscreen rules US Food and Drug Administration, proposed sunscreen rule (2019) and proposed order (2021); Final Administrative Order OTC000039 adding bemotrizinol, June 2026.
  6. Benzene recalls Johnson & Johnson voluntary recall of aerosol sunscreens, July 14, 2021.
  7. Oxybenzone and coral Downs CA, Kramarsky-Winter E, Segal R, et al. Toxicopathological effects of the sunscreen UV filter, oxybenzone (benzophenone-3), on coral planulae and cultured primary cells and its environmental contamination in Hawaii and the U.S. Virgin Islands. Arch Environ Contam Toxicol 2016;70(2):265–288. Search PubMed
  8. Vitamin D Neale RE, Khan SR, Lucas RM, et al. The effect of sunscreen on vitamin D: a review. Br J Dermatol 2019;181(5):907–915. doi:10.1111/bjd.17980. Passeron T, et al. Sunscreen photoprotection and vitamin D status. Br J Dermatol 2019;181(5):916–931.
  9. Application amount Ou-Yang H, Stanfield J, Cole C, Appa Y, Rigel D. High-SPF sunscreens (SPF ≥ 70) may provide ultraviolet protection above minimal recommended levels by adequately compensating for lower sunscreen user application amounts. J Am Acad Dermatol 2012;67(6):1220–1227. Search PubMed
  10. Skin of color Agbai ON, Buster K, Sanchez M, et al. Skin cancer and photoprotection in people of color: a review and recommendations for physicians and the public. J Am Acad Dermatol 2014;70(4):748–762. PMID 24485530. Systematic review of UV exposure and melanoma in skin of color, JAMA Dermatology 2021. PMID 33325988.
  11. Tinted sunscreen and melasma Castanedo-Cázares JP, Hernández-Blanco D, Carlos-Ortega B, Fuentes-Ahumada C, Torres-Álvarez B. Near-visible light and UV photoprotection in the treatment of melasma: a double-blind randomized trial. Photodermatol Photoimmunol Photomed 2014;30(1):35–42. PMID 24313385.
  12. Babies under 6 months US Food and Drug Administration; American Academy of Pediatrics, HealthyChildren.org.
  13. SPF, broad spectrum, water resistance, application American Academy of Dermatology public guidance; FDA sunscreen labeling rule (2011).
Ch. 5Retinoids: The Best Evidence After Sunscreen7
  1. Tretinoin Sitohang et al. 2022 (see Chapter 1).
  2. Retinol Kafi R, Kwak HSR, Schumacher WE, et al. Improvement of naturally aged skin with vitamin A (retinol). Arch Dermatol 2007;143(5):606–612. Search PubMed
  3. Adapalene and photoaging Bagatin E, Gonçalves HS, Sato M, Almeida LMC, Miot HA. Comparable efficacy of adapalene 0.3% gel and tretinoin 0.05% cream as treatment for cutaneous photoaging. Eur J Dermatol 2018;28(3):343–350. Search PubMed
  4. Cosmetic retinoids Milosheska D, Roškar R. Use of retinoids in topical antiaging treatments: a focused review of clinical evidence for conventional and nanoformulations. Adv Ther 2022. PMC9618501.
  5. Bakuchiol Dhaliwal S, Rybak I, Ellis SR, et al. Prospective, randomized, double-blind assessment of topical bakuchiol and retinol for facial photoageing. Br J Dermatol 2019;180(2):289–296. Search PubMed
  6. Short-contact tretinoin Veraldi S, Barbareschi M, Benardon S, Schianchi R. Short contact therapy of acne with tretinoin (pilot, open, multicenter study). J Dermatolog Treat 2013;24(5):374–376. doi:10.3109/09546634.2012.751085.
  7. Retinoids in pregnancy Tretinoin prescribing information (US and Canada). Kaplan YC, Ozsarfati J, Etwel F, Nickel C, Nulman I, Koren G. Pregnancy outcomes following first-trimester exposure to topical retinoids: a systematic review and meta-analysis. Br J Dermatol 2015;173(5):1132–1141. Systematic review and meta-analysis of first-trimester topical retinoid exposure (eight studies, 3,632,118 pregnancies). Front Drug Saf Regul 2026. doi:10.3389/fdsfr.2026.1864872.
Ch. 6Moisturizer and Cleanser: Simple and Cheap7
  1. Moisturizers for eczema van Zuuren et al. 2017 (see Chapter 1).
  2. Types of moisturizer in children Ridd MJ, Wells S, MacNeill SJ, et al. Effectiveness and safety of lotion, cream, gel, and ointment emollients for childhood eczema: a pragmatic, randomised, phase 4, superiority trial. Lancet Child Adolesc Health 2022;6(8):522–532. doi:10.1016/S2352-4642(22)00146-800146-8).
  3. Moisturizer prices Xu S, Kwa M, Lohman ME, Evers-Meltzer R, Silverberg JI. Consumer preferences, product characteristics, and potentially allergenic ingredients in best-selling moisturizers. JAMA Dermatol 2017;153(11):1099–1105. PMC5710429.
  4. Ceramide moisturizers Nugroho WT, Sawitri S, Astindari A, et al. The efficacy of moisturisers containing ceramide compared with other moisturisers in the management of atopic dermatitis: a systematic literature review and meta-analysis. Indian J Dermatol 2023;68(1):53–58. doi:10.4103/ijd.ijd_991_22. PMID 37151263. Chamlin SL, Kao J, Frieden IJ, et al. Ceramide-dominant barrier repair lipids alleviate childhood atopic dermatitis. J Am Acad Dermatol 2002.
  5. Moisturizers for healthy newborns Chalmers JR, Haines RH, Bradshaw LE, et al. Daily emollient during infancy for prevention of eczema: the BEEP randomised controlled trial. Lancet 2020;395(10228):962–972. Skjerven HO, Rehbinder EM, Vettukattil R, et al. Skin emollient and early complementary feeding to prevent infant atopic dermatitis (PreventADALL). Lancet 2020;395(10228):951–961. Kelleher MM, Phillips R, Brown SJ, et al. Skin care interventions in infants for preventing eczema and food allergy. Cochrane Database Syst Rev 2022. Search PubMed
  6. Soap and syndet cleansers Skin biophysical assessments of four types of soaps by forearm in-use test. J Cosmet Dermatol 2022;21(7):3127–3132. doi:10.1111/jocd.14589. PMID 34741581. Frosch PJ, Kligman AM. The soap chamber test: a new method for assessing the irritancy of soaps. J Am Acad Dermatol 1979;1(1):35–41.
  7. Petrolatum Ghadially R, Halkier-Sørensen L, Elias PM. Effects of petrolatum on stratum corneum structure and function. J Am Acad Dermatol 1992;26(3 Pt 2):387–396. Search PubMed
Ch. 7The Serum Shelf10
  1. Vitamin C Correia G, Magina S. Efficacy of topical vitamin C in melasma and photoaging: a systematic review. J Cosmet Dermatol 2023;22(7):1938–1945. Search PubMed
  2. Niacinamide Bissett DL, Miyamoto K, Sun P, Li J, Berge CA. Topical niacinamide reduces yellowing, wrinkling, red blotchiness, and hyperpigmented spots in aging facial skin. Int J Cosmet Sci 2004;26(5):231–238. Hakozaki T, Minwalla L, Zhuang J, et al. The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. Br J Dermatol 2002;147(1):20–31. Search PubMed
  3. Glycolic acid and photoaging Thibault PK, Wlodarczyk J, Wenck A. A double-blind randomized clinical trial on the effectiveness of a daily glycolic acid 5% formulation in the treatment of photoaging. Dermatol Surg 1998;24(5):573–577. PMID 9598014.
  4. AHAs and sun sensitivity Kaidbey K, Sutherland B, Bennett P, et al. Topical glycolic acid enhances photodamage by ultraviolet light. Photodermatol Photoimmunol Photomed 2003. PMID 12713551. Comparison of glycolic and salicylic acid, 2009. PMID 19411163.
  5. Salicylic and azelaic acid for acne Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol 2024;90(5):1006.e1–1006.e30. Search PubMed
  6. Azelaic acid and melasma Balina LM, Graupe K. The treatment of melasma: 20% azelaic acid versus 4% hydroquinone cream. Int J Dermatol 1991;30(12):893–895. PMID 1816137.
  7. Hyaluronic acid Pavicic T, Gauglitz GG, Lersch P, et al. Efficacy of cream-based novel formulations of hyaluronic acid of different molecular weights in anti-wrinkle treatment. J Drugs Dermatol 2011;10(9):990–1000. Search PubMed
  8. Peptides Robinson LR, Fitzgerald NC, Doughty DG, et al. Topical palmitoyl pentapeptide provides improvement in photoaged human facial skin. Int J Cosmet Sci 2005;27(3):155–160. Search PubMed
  9. Plant stem cells Trehan S, Michniak-Kohn B, Beri K. Plant stem cells in cosmetics: current trends and future directions. Future Sci OA 2017;3(4):FSO226. doi:10.4155/fsoa-2017-0026. PMC5674215.
  10. Snail secretion Tribó-Boixareu MJ, Parrado-Romero C, Rais B, et al. Clinical and histological efficacy of a secretion of the mollusk Cryptomphalus aspersa in the treatment of cutaneous photoaging. J Drugs Dermatol 2013. PMID 23652894. Randomized trial of snail secretion with snail egg extract, 2020. PMID 32308795.
Ch. 8Beauty You Swallow8
  1. Collagen supplements Myung SK, Park Y. Effects of collagen supplements on skin aging: a systematic review and meta-analysis of randomized controlled trials. Am J Med 2025;138(9):1264–1277. doi:10.1016/j.amjmed.2025.04.034. Pu SY, Huang YL, Pu CM, et al. Effects of oral collagen for skin anti-aging: a systematic review and meta-analysis. Nutrients 2023;15(9):2080. PMID 37432180.
  2. Nicotinamide and skin cancer Chen AC, Martin AJ, Choy B, et al. A phase 3 randomized trial of nicotinamide for skin-cancer chemoprevention. N Engl J Med 2015;373(17):1618–1626. PMID 26488693.
  3. Biotin and lab tests US Food and Drug Administration. The FDA warns that biotin may interfere with lab tests: FDA safety communication, November 28, 2017 (updated 2019).
  4. Biotin and skin Patel DP, Swink SM, Castelo-Soccio L. A review of the use of biotin for hair loss. Skin Appendage Disord 2017;3(3):166–169. PMID 28879195.
  5. Sunscreen pills US Food and Drug Administration warning letters to sellers of oral "sunscreen" supplements, May 2018, and statement by the FDA Commissioner.
  6. Water intake Akdeniz M, Tomova-Simitchieva T, Dobos G, Blume-Peytavi U, Kottner J. Does dietary fluid intake affect skin hydration in healthy humans? A systematic literature review. Skin Res Technol 2018;24(3):459–465. PMID 29392767.
  7. Low-glycemic diet and acne Smith RN, Mann NJ, Braue A, Mäkeläinen H, Varigos GA. A low-glycemic-load diet improves symptoms in acne vulgaris patients: a randomized controlled trial. Am J Clin Nutr 2007;86(1):107–115. PMID 17616769.
  8. Milk and acne Juhl CR, Bergholdt HKM, Miller IM, et al. Dairy intake and acne vulgaris: a systematic review and meta-analysis of 78,529 children, adolescents, and young adults. Nutrients 2018;10(8):1049. PMID 30096883.
Ch. 9Devices at Home, Treatments in the Clinic7
  1. LED light therapy Jagdeo J, Austin E, Mamalis A, et al. Light-emitting diodes in dermatology: a systematic review of randomized controlled trials. Lasers Surg Med 2018;50(6):613–628. PMID 29356026. Cohen M, Austin E, Masub N, Kurtti A, George C, Jagdeo J. Home-based devices in dermatology: a systematic review of safety and efficacy. Arch Dermatol Res 2022;314(3):239–246. doi:10.1007/s00403-021-02231-0.
  2. Light mask recall Johnson & Johnson voluntary recall of the Neutrogena Light Therapy Acne Mask, July 2019; Therapeutic Goods Administration (Australia) advice.
  3. Botulinum toxin Glogau R, Kane M, Beddingfield F, et al. OnabotulinumtoxinA: a meta-analysis of duration of effect in the treatment of glabellar lines. Dermatol Surg 2012;38(11):1794–1803. PMID 23106853.
  4. Filler complications Beleznay K, Carruthers JDA, Humphrey S, Jones D. Reviews of vision loss after filler injection, Aesthet Surg J 2015 and 2019, update 2024;44(10):1091. Kapoor KM, et al. Vision loss associated with hyaluronic acid fillers: a systematic review of literature. Aesthetic Plast Surg 2020. PMID 31822960.
  5. Microneedling for acne scars Sitohang IBS, Sirait SAP, Suryanegara J. Microneedling in the treatment of atrophic scars: a systematic review of randomised controlled trials. Int Wound J 2021;18(5):577–585. doi:10.1111/iwj.13559. PMID 33538106.
  6. Laser resurfacing for photoaging No reliable systematic review found; labeled Debated.
  7. Lasers and dark marks in skin of color Bin Dakhil A, Shadid A, Altalhab S. Postinflammatory hyperpigmentation after carbon dioxide laser: review of prevention and risk factors. Dermatol Reports 2023;15:9703. doi:10.4081/dr.2023.9703. Sowash M, Alster T. Review of laser treatments for post-inflammatory hyperpigmentation in skin of color. Am J Clin Dermatol 2023;24(3):381–396. doi:10.1007/s40257-023-00759-7.
Ch. 10Acne After Twenty8
  1. Adult acne prevalence Collier CN, Harper JC, Cafardi JA, et al. The prevalence of acne in adults 20 years and older. J Am Acad Dermatol 2008;58(1):56–59. Search PubMed
  2. Acne treatment guideline Reynolds et al. 2024 (see Chapter 7).
  3. Benzoyl peroxide strengths Mills OH Jr, Kligman AM, Pochi P, Comite H. Comparing 2.5%, 5%, and 10% benzoyl peroxide on inflammatory acne vulgaris. Int J Dermatol 1986;25(10):664–667. Search PubMed
  4. Antibiotic resistance Zaenglein AL, Pathy AL, Schlosser BJ, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol 2016;74(5):945–973, doi:10.1016/j.jaad.2015.12.037; Reynolds et al. 2024 (see Chapter 7).
  5. Over-the-counter adapalene US Food and Drug Administration press announcement, July 8, 2016.
  6. Birth control pills Arowojolu AO, Gallo MF, Lopez LM, Grimes DA. Combined oral contraceptive pills for treatment of acne. Cochrane Database Syst Rev 2012;(7):CD004425. Search PubMed
  7. Spironolactone Santer M, Lawrence M, Renz S, et al. Effectiveness of spironolactone for women with acne vulgaris (SAFA) in England and Wales: pragmatic, multicentre, phase 3, double blind, randomised controlled trial. BMJ 2023;381:e074349. Search PubMed
  8. Isotretinoin and mood Tan NKW, Tang A, MacAlevey NCYL, Tan BKJ, Oon HH. Risk of suicide and psychiatric disorders among isotretinoin users: a meta-analysis. JAMA Dermatol 2023 (published 2024;160(1):54–62). PMC10687715.
Ch. 11Dark Spots and Melasma9
  1. Melasma relapse Cohort study of 104 patients treated with Q-switched Nd:YAG laser for melasma, Northern Jiangsu Provincial People's Hospital, China. Int J Clin Exp Med 19(1).
  2. Tinted sunscreen Castanedo-Cázares et al. 2014 (see Chapter 4).
  3. Hydroquinone and triple-combination cream Rajaratnam R, Halpern J, Salim A, Emmett C. Interventions for melasma. Cochrane Database Syst Rev 2010;(7):CD003583. Search PubMed
  4. Hydroquinone rules and ochronosis US Food and Drug Administration, over-the-counter monograph reform under the CARES Act (September 2020); FDA safety information on skin-lightening products.
  5. Azelaic acid Balina and Graupe 1991 (see Chapter 7).
  6. Tranexamic acid Kim HJ, Moon SH, Cho SH, Lee JD, Kim HS. Efficacy and safety of tranexamic acid in melasma: a meta-analysis and systematic review. Acta Derm Venereol 2017;97(7):776–781. Meta-analysis of four randomized trials (480 patients) of oral tranexamic acid with triple-combination cream, 2024. Tranexamic acid prescribing information (clot risk). Search PubMed
  7. Lasers for melasma Lai D, Zhou S, Cheng S, Liu H, Cui Y. Laser therapy in the treatment of melasma: a systematic review and meta-analysis. Lasers Med Sci 2022;37(4):2099–2110. doi:10.1007/s10103-022-03514-2. Efficacy and safety of picosecond laser for the treatment of melasma: a systematic review and meta-analysis. Lasers Med Sci 2023;38(1):84. doi:10.1007/s10103-023-03744-y. Review of lasers in melasma. PMC5418955.
  8. Mercury in whitening creams World Health Organization. Elimination of mercury-containing skin lightening products; WHO news release, February 14, 2023. Minamata Convention on Mercury, Article 4. Zero Mercury Working Group product testing report, 2018–2019.
  9. Corticosteroids in whitening creams Skin-lightening cosmetics: frequent, potentially severe adverse effects. Prescrire Int 2011;20(119):208–215.
Ch. 12Sensitive, Red, Itchy Skin7
  1. Definition of sensitive skin Misery L, Ständer S, Szepietowski JC, et al. Definition of sensitive skin: an expert position paper from the Special Interest Group on Sensitive Skin of the International Forum for the Study of Itch. Acta Derm Venereol 2017;97(1):4–6. Search PubMed
  2. Irritant and allergic reactions to cosmetics DermNet NZ, Contact reactions to cosmetics. Prospective study of 151 patients with suspected cosmetic dermatitis, Sweden.
  3. Patch testing Johansen JD, Aalto-Korte K, Agner T, et al. European Society of Contact Dermatitis guideline for diagnostic patch testing. Contact Dermatitis 2015;73(4):195–221. Search PubMed
  4. Repeated open application test DermNet NZ, Open application test.
  5. Rosacea treatments van Zuuren EJ, Fedorowicz Z, Carter B, van der Linden MMD, Charland L. Interventions for rosacea. Cochrane Database Syst Rev 2015;(4):CD003262, doi:10.1002/14651858.CD003262.pub5, PMID 25919144.
  6. Topical steroid withdrawal Hajar T, Leshem YA, Hanifin JM, et al. A systematic review of topical corticosteroid withdrawal ("steroid addiction") in patients with atopic dermatitis and other dermatoses. J Am Acad Dermatol 2015;72(3):541–549. National Eczema Society, British Dermatological Nursing Group and British Association of Dermatologists, joint statement on topical steroid withdrawal, February 2024. Search PubMed
  7. Perioral dermatitis StatPearls, Perioral dermatitis (NCBI Bookshelf NBK525968).
Ch. 13Wrinkles and Aging: What's Realistic?6
  1. Facial skeleton and aging Mendelson B, Wong CH. Changes in the facial skeleton with aging: implications and clinical applications in facial rejuvenation. Aesthetic Plast Surg 2012;36(4):753–760. PMC3404279.
  2. Quitting smoking Serri R, Romano MC, Sparavigna A. "Quitting smoking rejuvenates the skin": results of a pilot project on smoking cessation conducted in Milan, Italy. Skinmed 2010;8(1):23–29. PMID 20839421.
  3. Sleep loss and appearance Axelsson J, Sundelin T, Ingre M, et al. Beauty sleep: experimental study on the perceived health and attractiveness of sleep deprived people. BMJ 2010;341:c6614. PMC3001961. Sundelin T, Lekander M, Kecklund G, et al. Cues of fatigue: effects of sleep deprivation on facial appearance. Sleep 2013;36(9):1355–1360. PMC3738045.
  4. Sugar and glycation Danby FW. Nutrition and aging skin: sugar and glycation. Clin Dermatol 2010;28(4):409–411, doi:10.1016/j.clindermatol.2010.03.018, PMID 20620757.
  5. Vegetables and wrinkles Nagata C, Nakamura K, Wada K, et al. Association of dietary fat, vegetables and antioxidant micronutrients with skin ageing in Japanese women. Br J Nutr 2010;103(10):1493–1498. Search PubMed
  6. Hormone therapy and wrinkles Owen CM, Pal L, Mumford SL, et al. Effects of hormones on skin wrinkles and rigidity vary by race/ethnicity: four-year follow-up from the ancillary skin study of the Kronos Early Estrogen Prevention Study. Fertil Steril 2016;106(5):1170–1175. The 2022 hormone therapy position statement of The North American Menopause Society. Menopause 2022. PMID 35797481.
Ch. 14Your Routine and Your Budget3
  1. A short routine Summary of Chapters 1, 4, 5 and 6: Hughes et al. 2013; Sitohang et al. 2022; van Zuuren et al. 2017.
  2. Children's skin care on social media Hales M, Lagu T, Rigali S, Paller A, Liszewski W. Pediatric skin care regimens on TikTok. Pediatrics 2025 (published online June 9, 2025). doi:10.1542/peds.2024-070309.
  3. Skin care for tweens and teens American Academy of Pediatrics, HealthyChildren.org. Trendy skin care for tweens and teens: is it safe? American Academy of Dermatology, A dermatologist's guide to skincare.
BackWorksheets at the back of the book1
  1. ABCDE signs of melanoma American Academy of Dermatology public guidance.

Updates and corrections

Evidence last reviewed October 15, 2026

Each evidence label shows how solid the evidence was on the day it was last reviewed. Corrections are posted here with the date they were made, and included in the next printing.

No corrections have been posted for this edition. Spotted an error, or a study that should change a label? Email [email protected]

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