However, in the overwhelming majority of males with hair loss, the cause is hereditary androgenetic alopecia, more commonly known as 'male pattern baldness'. Similarly, for females most patients presenting with hair loss have hereditary female pattern hair loss.

The condition is still being researched, but the hormone influences on hereditary hair loss in females may be different from those in males. Some of the less common causes of hair loss, which are reversible with treatment, include thyroid disease, iron deficiency, vitamins and minerals deficiency, high fever, surgery or general anaesthesia, “crash diets,” childbirth, and certain medications.

There are also certain dermatologic scalp disorders that can result in temporary or permanent hair loss, such as lupus, lichen planopilaris, and alopecia areata.

It is also important to remember that most adults lose approximately 75–125 hairs from their scalps every day due to the natural process whereby some hairs go into a dormant state (telogen), and others come out of this state and begin to sprout a new hair (anagen).