Hair Loss: Common Causes and Treatment

T. Grant Phillips, MD; W. Paul Slomiany, MD; Robert Allison, DO


Am Fam Physician. 2017;96(6):371-378. 

In This Article

Physiology of Hair Growth

Hair grows in three phases: anagen (active growing, about 90 % of hairs), catagen (degeneration, less than 10% of hairs) and telogen (resting, 5% to 10% of hairs). Hair is shed during the telogen phase.