What is the pH level of human hair?

The pH level of human hair typically ranges from 4.5 to 5.5, which is slightly acidic. This acidity helps to keep the hair cuticle smooth and closed, promoting healthy hair and reducing frizz. An appropriate pH also supports the scalp's natural lipid barrier, which is essential for maintaining moisture and preventing irritation.

In hair care, products that align with this pH range help to maintain the hair's equilibrium, ensuring that it remains strong and vibrant. When hair products are too alkaline, they can open the cuticle excessively, leading to damage and an increase in porosity, which can negatively affect the overall health and appearance of the hair. Understanding the normal pH level is essential for selecting appropriate hair care products and treatments that will not disrupt the hair's natural balance.