Anagen effluvium is a diffuse hair loss like telogen effluvium, but it develops much more quickly and can cause individuals to lose all their hair. Anagen Effluvium is the sudden hair loss which occurs as a result of chemicals or radiation, such as the hair loss that results during certain types of Chemotherapy or Radiation Treatment or those who have ingested toxic products like rat poison.

In Anagen effluvium the hair does not enter a resting stage as is does with Telogen effluvium.The onset of anagen effluvium is very rapid. Some individuals who start taking anti-cancer drugs can literally pull their hair out in clumps within the first two weeks. Because these drugs act so quickly and are so potent, the hair follicles have no time to enter into a telogen resting state, as with telogen effluvium, a response to a more moderate environmental challenge.

The hair fibers fall out quickly, but instead of looking like typical telogen hairs with little bulbs of keratin on the root end, the hairs that fall out are mostly dystrophic anagen hairs with a tapered or sometimes feathered root end.

While, the development of anagen effluvium is rapid, the recovery is also equally rapid. Because the follicles are just frozen in time, they are ready to grow once the factor causing the anagen effluvium has been removed.

The hair follicles are not destroyed, so there should be a normal hair growth density. However, some people notice a change in the nature of the hair fiber produced. Some people find their hair changes from straight to curly or vice versa, or sometimes there is a change in hair color. These changes may be permanent.