4. Castor Oil
Castor oil is another popular treatment for hair regrowth, although there is limited clinical evidence. The hormone prostaglandin (PGD2) is common in people with hair loss, and castor oil is believed to inhibit this hormone, slowing down the hair loss. Be aware that in rare cases the oil can cause felting, where the hair becomes irreversibly matted(2) after using castor oil or coconut oil. The advice is to use small amounts because everyone’s hair and scalp react differently.