What is the pH of Hair?

Your Hair's pH Level is important in maintaining healthy hair.

Along with embarrassing first crushes and less-than-ideal cafeteria lunches, we thought we left chemistry back in high school… but remember learning about pH in class? Turns out that maintaining a healthy pH level is extremely important when it comes to hair care!

What is pH?

pH, which stands for ‘power of hydrogen’, is a measurement scale used to specify how acidic or alkaline (or basic) a water-based solution is. The pH scale assumes neutrality at 7 and varies from zero to 14. Anything under 7 pH is considered to be acidic and anything over 7 pH is considered to be alkaline.

For reference, think lemon juice for an acidic solution (high concentration of hydrogen ions), water for a neutral solution (right in the middle at 7 pH), and bleach for an alkaline solution (low concentration of hydrogen ions).

How does pH relate to hair?

Typically, healthy hair is more on the acidic side — with a hair shaft pH of 3.67 and a scalp pH of 5.5.

Alkaline solutions (over 7 pH) help the cuticle soften and swell, letting whatever hair care products you’re using enter easily. Most alkaline products typically include hair bleach, relaxers, and ammonia-based hair dyes. These can all disrupt your hair’s natural pH levels and end up stripping and drying out your hair.

Products with higher pH levels (alkaline) can also cause an increase in the negativity of the electric network of the hair, that is, an increase of static electricity and the repulsion between strands. You can think of this as micro versions of rubbing a balloon on top of your hair, which can damage keratin (the protein your hair is made of). This damage can cause frizz, breakage, and significant changes to the structure of your hair.

Plus, if you’re using products with a high pH on your scalp, you could potentially cause dandruff and greasiness by negatively affecting your natural levels of bacteria and oils. Not great!

Maintaining a healthy pH for your hair helps retain moisture and protects you from bacteria that could lead to infections and disease.

How do I improve the pH balance of my hair?

We recommend using hair products that are as close to your natural pH levels as possible — between 3.67 and 5.5 pH. Keep in mind that not all hair is the same and some of us might have higher/lower pH levels than others.

Avoid hair products with high pH levels. Most of us probably don’t have a handful of pH strips that we can pull out after our morning shower, but a good rule of thumb is to avoid harsh ingredients like hair bleach, relaxers, and ammonia-based hair dyes. If you bleach or color your hair, supplement your treatments with more acidic professional hair care treatments or products.

While working on perfecting your hair care routine, remember to look closely at labels and test your products if you’re curious. Using a pH-balanced shampoo and conditioner and rinsing thoroughly is the safest bet when trying to maintain healthy hair!

If you’re looking to find out more about your own hair products, you can purchase these easy-to-use pH strips and find out how your treatment matches up.

Profile photo for Evan Zhao

Reviewed by: Evan Zhao, PhD

Evan is a synthetic biologist and chemical engineer. He completed his BS from Caltech, and his MA and PhD from Princeton University. He received the prestigious Schmidt Science Fellowship as a postdoctoral fellow at MIT/Harvard and has published in the world's top scientific journals including Nature, Nature Biotechnology, Nature Chemical Biology, and more.

Written by: Revela Editorial Team

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