Optimal pH Range for Facial Cleansers
The optimal pH range for a liquid facial cleanser is 5.5-7.0, which is close to the skin's natural pH and minimizes damage to the skin barrier while maintaining adequate cleansing efficacy.
Understanding pH and Skin Health
- Healthy skin has a naturally acidic pH of approximately 5.5, which helps maintain the skin barrier function and protect against pathogens 1
- Cleansers with pH values significantly different from the skin's natural pH can disrupt the skin barrier, leading to dryness, irritation, and potential skin conditions 1, 2
- The pH of facial cleansers on the market varies widely, ranging from 3.59 to 10.83, with many products not disclosing their pH 2
Types of Cleansers and Their pH
Soaps
- Traditional soaps are made from lye and natural fats, resulting in a highly alkaline pH of approximately 9-10 3
- While effective at removing dirt and inactivating viruses, alkaline soaps remove beneficial intracellular lipids and damage proteins in the stratum corneum 3
- This damage compromises the skin barrier and increases skin sensitivity and irritation 3, 4
Synthetic Detergents (Syndets)
- Syndets contain less than 10% soap and have a pH of 5.5-7, which is similar to the pH of healthy skin 3
- These cleansers use chemical surfactants that function similarly to soap but are generally milder 3
- Liquid syndets are more likely to have an acidic pH (84.9% of tested products), making them more suitable for facial skin 2
Lipid-Free Cleansers
- These contain no soap (no fat or oil), can clean without water, and leave a thin moisturizing residue containing glycerin or glycol 3
- They are generally formulated at a skin-friendly pH and are suitable for sensitive skin 3
Clinical Evidence on pH and Skin Irritation
- Research has demonstrated a significant correlation between the pH of cleansers and their irritation potential (p < 0.006) 4
- High pH (pH 10) solutions, even without surfactants, can increase stratum corneum swelling and alter lipid rigidity, potentially damaging the skin 1
- Studies comparing identical cleanser formulations differing only in pH showed that those with neutral pH (close to 7) caused less skin dryness and irritation than those with very low pH when using anionic surfactants 5
Recommendations for Facial Cleansers
- Choose synthetic detergent (syndet) cleansers with a pH between 5.5-7.0 for facial cleansing 3, 2
- Avoid traditional soaps with alkaline pH (9-10) for facial use, as they can significantly damage the skin barrier 3, 4
- For sensitive or compromised skin (such as atopic dermatitis), cleansers with pH closer to 5.5 are preferred 2
- Consider the surfactant composition along with pH, as certain surfactants can be more irritating regardless of pH 5
Potential Pitfalls and Considerations
- Many products marketed for "sensitive skin" still have considerable irritation potential and may not disclose their pH 4
- A product formulated at "skin pH" does not automatically guarantee mildness; the interaction between surfactants and other ingredients with the skin at that pH is equally important 5
- The mildness of a cleanser is determined by both its pH and the specific surfactants used 1, 5
- Extended use of cleansers with inappropriate pH can lead to increased bacterial colonization, especially with prolonged use 6