Causes of Telogen Effluvium

A relatively large number of drugs can cause “telogen effluvium,” a condition where hair is shifted into a resting, non-growth stage and then several months later shed. Fortunately, this shedding is reversible if the medication is stopped, but the reaction can be confused with genetic female hair loss if not properly diagnosed. 

Telogen Effluvium (TE) is probably the second most common form of hair loss that a dermatologist sees in the dermatology clinic. To understand the condition it is better to have a look at the biology of the hair follicle. The condition results when the number of hairs in the growth phase drops significantly and there is a corresponding increase in telogen (resting) stage hair follicles. TE characterized by thinning of the hair does not follow any particular pattern, but generally there is more thinning on top of the scalp than at the sides and back of the scalp. There is no hair line recession, except for few rare cases of chronic telogen effluvium which results from shortening of the growth phase. The hairs that are shed are typically telogen hairs which can be recognized by a small bulb of keratin on the root end. Telogen affluvium can also result if the telogen phase is prolonged; in this case the hair fibers do not fall but remain in resting stage for longer time. Due to prolongation of telogen stage, anagen phase is not resumed at those places and a gradual thinning of hair is seen.