Hair loss, alopecia or alopecia refers to the loss of hair from the head or body. Alopecia can refer to hair loss in general or male pattern hair loss. Hair loss and hypotrichosis have many causes including androgenetic alopecia, fungal infection, psychological trauma (eg trichotillomania), radiotherapy, chemotherapy, nutritional deficiencies (eg iron deficiency and autoimmune diseases such as coccidiosis). Alopecia and severe hair loss.