Hair mildew, a type of mold that grows on hair, is caused by excessive moisture and poor hygiene. It can appear as white, yellow, or green spots on the hair shaft and can cause the hair to become brittle and break easily. Hair mildew is most common in people who live in humid climates or who do not wash their hair regularly.
Hair mildew can be treated with over-the-counter antifungal shampoos or with prescription medications. It is important to treat hair mildew as soon as possible to prevent it from spreading and causing further damage to the hair.