What Is Telogen Effluvium?

Most of the hairs on the body are actively growing (the anagen phase) and the others are resting (the telogen phase). A hair stays in the growing phase for two to four years, before moving into the resting phase. A hair rests between two and four months, and then falls out and is replaced by a new, growing hair. The average person loses about 100 hairs a day.

In a person with Telogen Effluvium more hairs move into the resting phase, so instead of shedding 100 hairs every day, you may lose up to 300 hairs a day instead, resulting in a thinness of hair volume. 

What causes Telogen Effluvium?

There are some common triggers for Telogen Effluvium, however, in about 30% of people affected, no cause can be found. Common causes include:

  • Surgery
  • Physical injury
  • Psychological stress
  • High fever, infection or illness
  • Weight loss
  • Change in diet
  • Hormonal changes, such as childbirth and menopause
  • Iron deficiency
  • Hypothyroidism or hyperthyroidism
  • Some medications

Hairs don’t usually fall out until two to four months after they have entered the resting phase, so you may not notice any hair loss until two to four months after the event that caused the problem. Telogen Effluvium rarely lasts longer than six months although, in some cases, can last for years.

What does Telogen Effluvium look like?

In cases of Telogen Effluvium, hair falls out in a diffuse pattern, all over the scalp. Your hair may feel thinner and you may notice more hair shedding than usual. It can be scary to lose so many hairs so rapidly, but each hair that is goes into the resting phase is replaced by a new, growing hair, so all of the hair will not fall out.

How is Telogen Effluvium diagnosed?

Telogen Effluvium is usually diagnosed based on your medical history and an examination of the scalp and hair. Your dermatologist may pull on your hair to see how much comes out, and you may be asked to collect all the hairs that fall out in a twenty-four-hour period. Your dermatologist may also run some blood tests to check for conditions such as thyroid abnormalities that can cause hair loss.

How long will Telogen Effluvium last?

Telogen Effluvium usually resolves itself completely within six to nine months. The normal length of the telogen phase is around three to six months, after which the hair begins to grow again. How long it takes for hair volume to return to normal will vary according to the length of hair. In some cases, the condition may last longer and in some rare cases, not all hairs grow back. This is often referred to as Chronic Telogen Effluvium. In Chronic Telogen Effluvium, hair loss can last for years, although as with Telogen Effluvium, people will not go bald. Chronic Telogen Effluvium usually stabilises after a few years.

Can Telogen Effluvium be treated?

There is normally no treatment required for Telogen Effluvium, as the hair will start growing once the cause of the hair loss is removed. In cases where not all the hair has grown back, your dermatologist may prescribe minoxidil, which is a lotion applied to the scalp that may stimulate hair growth in some people.

Additional Information:

The British Association of Dermatologists (BAD) has produced a Patient Information Leaflet for Telogen Effluvium.


The British Hair and Nail Society also provide Patient information leaflets: