How do i know if i have alopecia areata or telogen?

See a dermatologist: Usually an office visit can define a. Areata vs telogen. Usually areata presents with 1 or more bald areas with specific type loose hair at the edge. Often there are nail changes. There may be relatives with areata, maybe prior attacks. Telogen will be diffuse, often with a history of weight loss or serious illness or surgery a few months before.