Glycerin, also known as glycerol, comes from natural resources and can also be synthetically derived. It attracts moisture when in an environment of 70 percent humidity or higher. Consumers have expressed health concerns about synthetic glycerin, but natural forms are also available. Dry hair can occur for a variety of reasons including low humidity, wind and sun exposure, and use of hair-styling products.

Glycerin is a humectant, designed to bring moisture in and retain it. In hair products, glycerin works to draw moisture onto your hair and provides a barrier to keep the moisture locked in. Glycerin can be used as an ingredient in a shampoo or conditioner. In hair serums, glycerin is applied directly to the hair after washing.

There are two types of glycerin: natural and synthetically derived. Natural sources of glycerin include vegetable oils or animal fats. If glycerin is from a natural source it will often be indicated on the label.

When derived synthetically, petrochemicals undergo chemical synthesis to produce glycerin. Larry O’Hanlon, a reporter with Discovery News, reports that petrochemicals have been shown to pose health risks, including lowering sperm count in future generations.

In the right environment, with humidity at 70 percent or higher, glycerin has the ability to draw in moisture and help your hair retain moisture. It is soluble in water and easily added to hair-care products.

The Centers for Disease Control and Prevention indicate that glycerin in mist form may irritate your eyes and skin if it comes in direct contact. If inhaled, glycerin is also capable of causing respiratory problems, headache, vomiting and nausea.

Synthetic glycerin may be carcinogenic, according to the Environmental Working Group’s Cosmetic Database. The Registry of Toxic Effects of Chemical Substances indicates positive mutation results occurred when exposed to glycerin.

If you have dry hair, use a hair product with glycerin in environments with at least 70 percent humidity. If you suffer from frizzy or curly hair, avoid using glycerin as it will add more moisture to your hair and add to your frizz problems.

In very dry environments, glycerin will draw moisture out of your hair. Avoid using glycerin if you are in dry environments, as it may dry your hair out even more.

Also, glycerin is able to penetrate the hair cuticle and strip away any chemical colors that may be present. According to curl chemist Tonya Mckay Beckar, if you use a semipermanent hair color, glycerin is able to strip away the color quite easily. If you use permanent hair colors, the particles are much smaller and absorb more quickly. After the first washing, the color particles are absorbed into the hair shaft and glycerin will not be able to strip the color away.