Which of the following options correctly identifies the hair pH range?

• A. 7.0 - 8.0
• B. 3.0 - 4.0
• C. 4.5 - 5.5
• D. 6.0 - 7.0

Answer: (C)

Hair thrives in a slightly acidic environment, with the natural hair pH sitting roughly between 4.5 and 5.5. This level keeps the cuticle scales lying flat and the cortex’s bonds stable, which gives smooth texture, shine, and better moisture and color retention. Styling and cleansing products are formulated to stay in this narrow acidic range so the cuticle doesn’t swell or lift. When pH moves into alkaline territory (above about 7), the cuticle lifts, increasing porosity, frizz, and color fading. If the pH is much lower, the hair can become dry and product performance can suffer. Because 4.5 to 5.5 aligns with the hair’s natural state and supports cuticle integrity and product effectiveness, it’s the range that best fits hair health and maintenance.