Anagen Hair

Anagen Effluvium Explained

During normal hair growth, actively replicating cells in the lower part of the hair follicle are extruded upwards to produce hair strands. This period, when the hair follicle is actively growing and lengthening, is referred to as the anagen phase of the hair growth cycle. Healthy, long growing hair strands are therefore referred to as anagen hairs.

This detailed illustration of the hair bulb region shows the germinal matrix cells surrounding the dermal papilla which are responsible for hair growth.

Base of Hair Follicle (Hair Bulb)

“Effluvium” is the medical term for hair shedding. Anagen Effluvium occurs when hair follicles that are actively growing, (i.e. hair follicles in the anagen phase of the growth cycle), are exposed to a severe toxic, inflammatory or other insult.

The rapidly dividing cells (i.e. cells undergoing mitotic activity) surrounding the hair follicle papilla, that cause the hair shaft to lengthen, are severely affected. The subsequent disruption of normal mitotic activity causes the lengthening hair shaft to become progressively narrow and very frail. Eventually the base of the hair shaft is too narrow to support the hair strands; the narrowed and frail hair strand can then break off, and shed.

As the progressively narrowing hair strand continues to grow, the remaining broken off hairs have a narrow base and are wider at the tip, resembling an exclamation point.


Anagen Effluvium is most frequently seen following chemotherapy and is often referred to as chemotherapy-induced hair loss. Hair shaft breakage and shedding usually are noted within 2 weeks after the toxic chemotherapeutic agent is received. Since around 90% of scalp hair follicles are in anagen phase, anagen effluvium can be very dramatic, causing wholesale shedding and hair loss. Fortunately, when the offending agent is discontinued the damaged hair follicles will typically regenerate. Similar effects can be seen from a host of toxins, heavy metals and medications.


Inflammation can also cause disruption of mitotic activity and anagen effluvium. This is what occurs with alopecia areata and other inflammatory conditions that affect the hair follicle papilla cells, such as syphilis.


Various nutrients are vital for normal cellular growth. The heightened cellular activity needed for healthy hair shaft growth, is therefore easily affected by various macronutrient and micro-nutrient deficiencies. Fad diets, unhealthy dietary habits, protein poor vegetarian/vegan diets, as well as severe malnutrition, such as Kwashiorkor, have varying effects.

Diganostic Features

The damaged, anagen efflivium, hair shaft is tapered at the base; this feature is easily identified when viewed under magnification. As described above, the tapered hair shafts look like exclamation points and are therefore called exclamation hairs. Punch biopsy of the scalp will typically show a normal anagen/telogen ratio of around 90% anagen/10% telogen hair follicles. A biopsy with greater than 15% of the hair follicles in telogen phase, is indicative of telogen effluvium.

Please consult with your physician before considering any of the drugs or treatments discussed on this website