Hair fibres are small cosmetic fibres that cling to existing hair and reduce the visual contrast between scalp and hair. They can be helpful for diffuse thinning, crown thinning or parting widening when enough native hair remains for the fibres to attach to. They wash out and do not treat the underlying cause of hair loss. Fibres can be a useful confidence tool while medical treatment is taking effect, but they may look unnatural if overused or applied to very bare scalp.
BAD alopecia areata: https://www.bad.org.uk/pils/alopecia-areata ; DermNet hair replacement surgery: https://dermnetnz.org/topics/hair-replacement-surgery
