Gavazzoni Dias Maria Fernanda Reis, de Almeida Andréia Munck, Cecato Patricia Makino Rezende, Adriano Andre Ricardo, Pichler Janine
Department of Dermatology, Ambulatório Geral de Dermatologia. Instituto de Dermatologia Prof. Rubem David Azulay. Rio de Janeiro Brazil.
Int J Trichology. 2014 Jul;6(3):95-9. doi: 10.4103/0974-7753.139078.
Dermatologists most frequently prescribe shampoos for the treatment of hair shed and scalp disorders. Prescription of hair care products is often focused on improving scalp hair density, whereas the over-the-counter products focus on hair damage prevention. Little is taught in medical schools about the hair cosmetics, so that the prescriptions are based only on the treatment of the scalp and usually disregards the hair fiber health.
In this work, we review the current literature about the mode of action of a low-pH shampoo regarding the hair shaft's health and analyze the pH of 123 shampoos of international brands.
All shampoo pH values ranged from 3.5 to 9.0. 38.21% of all 123 shampoos presented a pH ≤ 5.5 (IC: 29.9-47%) and 61.78% presented a pH > 5.5. 26 anti-dandruff shampoos were analyzed. About 19.23% presented pH ≤ 5.5.(IC: 7.4-37.6%). 80.77% of all anti-dandruffs shampoos presented a pH > 5.5. The dermatological shampoo group (n = 19) presented 42.10% with pH ≤ 5.5 (IC: 21.8-64.6%), and 57.90% with pH > 5.5. Among the commercial (popular) products (n = 96), 34.37% presented pH ≤ 5.5 (IC: 25.4-44.3%) and 65.62% presented pH > 5.5. 15 professional products (used in hair salons) were analyzed, of which 75% had a pH ≤ 5.5 (IC: 18-65, 4%), and 25% had a pH > 5.5. 100% of the children's shampoos presented a pH > 5.5.
Alkaline pH may increase the negative electrical charge of the hair fiber surface and, therefore, increase friction between the fibers. This may lead to cuticle damage and fiber breakage. It is a reality and not a myth that lower pH of shampoos may cause less frizzing for generating less negative static electricity on the fiber surface. Interestingly, only 38% of the popular brand shampoos against 75% of the salons shampoos presented a pH ≤ 5.0. Pediatric shampoos had the pH of 7.0 because of the "no-tear" concept. There is no standardized value for the final pH. The authors believe that it is important to reveal the pH value on the shampoo label, but studies are needed to establish the best pH range for both the scalp and the hair fiber's health.
皮肤科医生最常开具洗发水用于治疗脱发和头皮疾病。护发产品的处方通常侧重于提高头皮头发密度，而非处方产品则侧重于预防头发损伤。医学院校很少教授毛发化妆品相关知识，因此处方仅基于头皮治疗，通常忽视了毛发纤维的健康。
在本研究中，我们回顾了当前关于低pH值洗发水对毛干健康作用方式的文献，并分析了123种国际品牌洗发水的pH值。
所有洗发水的pH值范围为3.5至9.0。在123种洗发水中，38.21%的pH值≤5.5（置信区间：29.9 - 47%），61.78%的pH值>5.5。分析了26种去屑洗发水，约19.23%的pH值≤5.5（置信区间：7.4 - 37.6%），80.77%的去屑洗发水pH值>5.5。皮肤科专用洗发水组（n = 19）中，42.10%的pH值≤5.5（置信区间：21.8 - 64.6%），57.90%的pH值>5.5。在商业（大众）产品（n = 96）中，34.37%的pH值≤5.5（置信区间：25.4 - 44.3%），65.62%的pH值>5.5。分析了15种专业产品（用于美发沙龙），其中75%的pH值≤5.5（置信区间：18 - 65.4%），25%的pH值>5.5。100%的儿童洗发水pH值>5.5。
碱性pH值可能会增加毛发纤维表面的负电荷，从而增加纤维之间的摩擦力。这可能导致角质层损伤和纤维断裂。洗发水pH值较低会减少纤维表面产生的负静电，从而减少毛糙，这是事实而非神话。有趣的是，只有38%的大众品牌洗发水pH值≤5.0，而美发沙龙洗发水这一比例为75%。由于“无泪”概念，儿童洗发水的pH值为7.0。最终pH值没有标准化数值。作者认为在洗发水标签上标明pH值很重要，但需要开展研究以确定对头皮和毛发纤维健康均最佳的pH值范围。
