Humectants

What humectants do

Humectants are water-attracting ingredients — glycerin, propylene glycol, sorbitol, panthenol, honey and hyaluronic acid among them. In a formula they help hold water where you want it and contribute to a soft, flexible feel.

The humidity claim, examined

The popular rule says glycerin pulls water from the air in humidity and causes frizz, and pulls water out of hair in dry air. The underlying physics isn't fictional, but the rule is stated far more confidently than the evidence supports.

Real formulas contain humectants alongside oils, film formers and conditioning agents that change the outcome. Concentration matters. So does what the rest of your routine is doing.

"Glycerin + humidity = bad" is too blunt to be useful. Observe your own results across seasons instead.

Using them well

• Judge the finished product, not one ingredient in it.
• If a product behaves differently in summer and winter, that's information worth recording.
• Sealing a humectant-containing layer with a lightweight oil or cream is a common approach worth trying.