How hair grows

How Hair Grows

The average scalp has 100,000 hairs. Each follicle produces a single hair that grows at a rate of half an inch per month. After growing for two to six years, hair rests awhile before falling out. It's soon replaced with a new hair, and the cycle begins again. At any given time, 85% of hair is growing, and the remainder is resting.

How Much Hair Loss Is Normal?

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Because resting hairs regularly fall out, most people shed about 50-100 strands every day. You'll typically find a few in your hairbrush or on your clothes. Abnormal hair loss can happen in several ways. You may notice dramatic clumps falling out when you shampoo or style. Or your hair may thin slowly over time. If you're concerned about changes in your hair, check with your doctor.

Info source: 

http://www.m.webmd.com/skin-problems-and-treatments/ss/slideshow-womens-hair-loss?ecd=wnl_wmh_102413&ctr=wnl-wmh-102413_ld-stry&mb=GULHw1r0yczQttMGkoWNR%40HnVev1imbCX2R%2fDNcXcrE%3d