Physicians should be careful not to underestimate the emotional impact of hair loss for some patients. Patients may present with focal patches of hair loss or more diffuse hair loss, which may include predominant hair thinning or increased hair shedding. Focal hair loss can be further broken down into scarring and nonscarring. Scarring alopecia is best evaluated by a dermatologist. The cause of focal hair loss may be diagnosed by the appearance of the patch and examination for fungal agents. A scalp biopsy may be necessary if the cause of hair loss is unclear. Alopecia areata presents with smooth hairless patches, which have a high spontaneous rate of resolution. Tinea capitis causes patches of alopecia that may be erythematous and scaly. Male and female pattern hair losses have recognizable patterns and can be treated with topical minoxidil, and also with finasteride in men. Sudden loss of hair is usually telogen effluvium, but can also be diffuse alopecia areata. In telogen effluvium, once the precipitating cause is removed, the hair will regrow.