At any given time, about 85% to 90% of the hairs on the average person's head are actively growing (the anagen phase) and the others are resting (the telogen phase). Typically, a hair is in the anagen phase for two to four years, then enters the telogen phase, rests for about two to four months, and then falls out and is replaced by a new, growing hair. The average person naturally loses about 100 hairs a day.
In a person with telogen effluvium, some body change or shock pushes more hairs into the telogen phase. Typically in this condition, about 30% of the hairs stop growing and go into the resting phase before falling out. So if you have telogen effluvium, you may lose an average of 300 hairs a day instead of 100.
Telogen effluvium can be triggered by a number of different events, including:
- Major physical trauma
- Major psychological stress
- High fever, severe infection or other illness
- Extreme weight loss
- Extreme change in diet
- Abrupt hormonal changes, including those associated with childbirth and menopause
- Iron deficiency
- Hypothyroidism or hyperthyroidism
- Some medications
Because hairs that enter the telogen phase rest in place for two to four months before falling out, 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 some cases last longer.
Although losing a great number of hairs within a short time can be frightening, the condition is usually temporary. Each hair that is pushed prematurely into the telogen phase is replaced by a new, growing hair, so there is no danger of complete baldness. Because hair on the scalp grows slowly, your hair may feel or look thinner than usual for a time, but fullness will return as the new hairs grow in.
If you have telogen effluvium, you'll notice more hair than usual accumulating on your pillowcase, on the shower or bathroom floor and in your hairbrush. Your scalp hair may feel or look less dense than usual. Often, though, the hair loss is subtle, and other people may not notice anything different about your hair.
Most cases of telogen effluvium can be diagnosed based on medical history and an examination of the scalp and hair. If the hair loss has been occurring for several months, there may be visible thinning patches, but often the hair loss is not dramatic enough for a doctor to notice. If you have large bald patches, you probably don't have telogen effluvium. If the doctor gently tugs on some hairs on your scalp and four or more hairs come out, you probably have telogen effluvium. Also, the hairs will look like hairs in the telogen phase -- they will have a white bulb at the end that was in the scalp, and will not have a gel-like covering around that end of the hair.
You may be asked to gather all hairs that fall out of your head over a 24-hour period, and count them to see if the hair loss is truly excessive. Losing fewer than 100 hairs in a day is considered normal. You also may be asked to gather and count lost hairs every one or two weeks to see when the shedding starts to decline.
In some rare cases, if there is reason to doubt the diagnosis, a biopsy of the scalp may be done. In this procedure, a small piece of the scalp that includes several hair follicles is removed and examined under a microscope. Your doctor also may do blood tests to check for conditions such as thyroid abnormalities that may be contributing to hair loss.
Typically, hair loss begins two to four months after the event that triggered the problem, and lasts approximately six months. New hairs begin growing immediately after the hair falls out, but significant growth may not be noticed for several months.
Nothing can be done to prevent most of the types of physical shock that can start telogen effluvium. Some cases may be caused by a poor diet, and these might be prevented by eating a balanced diet that provides enough protein, iron and other nutrients.
No treatment for active telogen effluvium has been proven effective.
Some causes of the disorder can be corrected. For example, if you have a poor diet, consult a dietitian to help you balance it. If the hair loss began after you started a new medication, talk to your doctor to see if the medication should be discontinued. Many times, however, the cause is a specific event in the past, and you can expect that the hair will grow back. In cases where hair growth has not returned to a satisfactory level, your doctor may prescribe minoxidil (Rogaine), a lotion applied to the scalp that may stimulate hair growth in some people.
See your doctor if you experience excessive hair loss or obvious thinning patches on your scalp.
The outlook for telogen effluvium is very good. Most cases run their course within six to nine months, and the hair usually grows back. In some cases, the disorder may last longer. In other cases, not all hairs grow back.
American Academy of Dermatology
P.O. Box 4014
Schaumburg, IL 60168-4014