Castile soap is a versatile cleaner that is made from vegetable oil instead of synthetic material or animal fats. It is considered to be environmentally friendly because of reduced chemical use, organic ingredients and improved biodegradability. Castile soap is often made with olive oil but may contain coconut, jojoba or other essential oils. Most natural health or beauty stores offer castile soap in either bar or liquid form, enabling users to wash hair as well as skin.

Look for a brand of castile soap that contains olive oil or other moisturizing ingredients. This will improve the quality and hydration of your hair. While castile soap is available in both liquid and bar form, the liquid form will be easier to use as a shampoo.

Apply soap to hair and lather thoroughly. The lather may not be as thick as traditional shampoos because the chemical composition is different. Use fingertips to massage the scalp, as the essential oil in the soap is beneficial for follicle stimulation.

Leave shampoo on hair for three to five minutes and then rinse thoroughly with warm water. The glycerin content of castile soap may leave hair feeling slightly sticky.

Condition if desired. For people with oily or well-hydrated hair, conditioner may not be necessary after using castile soap. Alternatively, combine 2 tbsp. of apple cider vinegar and 8 oz. of cooled herbal tea or water to use as a conditioning rinse.

Be patient, as it may take hair time to adjust. Try the shampoo daily for one to three weeks, and use conditioner if the castile soap alone leaves hair too dry.

Try making your own moisturizing castile soap shampoo by combining a quarter-cup liquid castile soap, a quarter-cup distilled water, 1 tsp. olive oil or another essential oil and 1 tsp. glycerin. The added ingredients will improve the hydrating properties of the shampoo and may be particularly useful to those with dry hair.