Histology is similar to telogen or anagen effluvium on biopsy.

Medications can lead to two types of hair loss: telogen effluvium and Anagen effluvium.

Anagen effluvium is the pathologic loss of anagen or growth-phase hairs.

Anagen effluvium is hair loss that occurs during the anagen phase of the hair cycle, when the hairs are actively growing.

A disruption of the growing phase causes abnormal loss of anagen hairs (anagen effluvium).