Telogen effluvium is a common form of alopecia. It occurs when hair follicles move from the anagen phase to the telogen phase too early. Around 85% of scalp hairs are in the anagen phase, which means that the hair grows by 0.5-1.5cm a month and lasts in the scalp around three-five years. Telogen is when the hair follicle is approaching the end of its lifecycle. The hair is fully keratinized and the follicle is dormant, lasting in the scalp around two-three months¹.
The normal hair cycle is illustrated in the diagram below:
Acute telogen effluvium can happen suddenly and generally comes on about three months after a trigger. Common triggers include childbirth, severe trauma or illness, a stressful or major life event, rapid weight loss, severe skin problems affecting the scalp or a new medication¹’³. Patients may notice large numbers of hairs on their pillow, hairbrush or in the plughole. In most cases, hair growth returns to normal within a few months¹. If the hair loss carries on for more than six months, this could suggest chronic telogen effluvium. It is more common in women and is linked to female pattern hair loss, thyroid disease and iron and vitamin D deficiencies¹.