Hair Shedding Causes and Treatment

Any cause of hair loss, if sudden and severe enough, will cause shedding (another reason to be sure to get an accurate diagnosis). This page has information on causes of shedding not related to male or female pattern hair loss. This form of hair loss is called an effluvium.

An effluvium is any sort of discharge, usually unpleasant. Think effluent. That pretty well sums up the unwelcome sudden loss of (usually large) amounts of hair that can occur as a result of a medical condition or some drugs.

The reason hair is such a sensitive indicator of our health is because it is very active and busy. Hair grows on average 1 cm a month or 0.3mm a day. For the average scalp with 100,000 hairs that means about a kilometre of hair is produced each month. The cells in the follicles are very busy and metabolically active. Because they need to work at such a high capacity they need a constant high level supply of nutrients. You have to be in peak physical condition to grow a healthy head of hair. When these nutrients are not present the follicles stop growing. Toxins and drugs, even tiny doses, can stop follicles growing. When follicles stop growing they automatically eject the hair they contain and wait until conditions improve and they get the signal to grow a new hair.


There are two types of effluvium, telogen and anagen. They relate to the two major parts of the hair growth cycle. Hair follicles do not constantly grow hair but cycle between anagen (hair growth phase) and telogen (resting phase). The longer the anagen part of the cycle the longer the hair. We all vary in the length of the anagen part of our cycle which is why some people can grow hair to their waist but others can only grow to their shoulders. When anagen stops, either because it is programmed to stop or some insult has halted hair growth the follicle enters telogen or the resting part of the cycle. On the scalp follicles spend 90% of their time in anagen and 10% in telogen. Each follicle follows its own cycle, unlike many animals who grow a thick winter coat and shed heavily in spring. 


If nutrient levels are not high enough to sustain hair production  a large number of active anagen hair follicles will switch into the resting telogen phase and that person will experience a large shed. The same thing will happen if the body experiences some sort of illness or trauma severe enough to divert nutrients from the hair. An acute telogen effluvium is usually due to a sudden brief stress or temporary nutrient loss. A chronic telogen effluvium is due to some sort of chronic condition, often difficult to diagnose.

Telogen effluvium (TE) usually occurs diffusely over the scalp although some women may notice it more over the temples. If you look at the hair which has fallen out you will see a white bulb at the base. In this way you can tell whether your hair loss is due to TE or hair breakage (no bulbs visible on broken hairs).


Very severe stresses will halt anagen so rapidly that the hair follicle does not have time to transform to telogen before the hair is ejected. The most common cause of anagen effluvium (AE) is chemotherapy and radiotherapy. It can occur in some poisonings. Hair loss is just a small part of the severe effects caused by these.

The cause of anagen effluvium is always obvious. Hair loss is sudden  (more rapid than TE) and is usually total or nearly total, usually including eyebrows and body hair.

Studies are underway into whether scalp cooling during chemotherapy treatment will prevent or reduce AE. If the hair follicles are cold enough they will enter a form of “suspended animation” and not absorb the chemotherapy dose. The risk is that any cancer cells present in the scalp will not absorb the chemotherapy either. We await the results.

There are case reports suggesting it is possible to reduce or sometimes avoid the eyelash and eyebrow loss of chemotherapy by the use of bimatoprost. This topical treatment is most commonly used to lengthen eyelashes and thicken eyebrows as well as treat glaucoma.


This can be difficult to diagnose. If the cause is only present for a brief period then the bout of TE will also be brief and the patient will recover. If the scalp is otherwise healthy the recovery will be full. If the patient also has male or female pattern hair loss, either known or undiagnosed, then recovery will be incomplete and hair loss will be ongoing. Causes of TE include:

  • Major illness
  • Major trauma
  • Significant surgery
  • Significant weight loss, especially if the BMI falls below 20
  • Iron deficiency
  • After pregnancy
  • Vaccinations in susceptible individuals
  • Drugs and medications in susceptible individuals (especially high dose vitamin A, commonly antihistamines)
  • Chronic illness especially chronic inflammatory illness such as forms of  arthritis or inflammatory bowel disease
  • Acute or chronic stress
  • Other vitamin or mineral deficiencies such as  zinc
  • Overactive or underactive thyroid
  • Probably endocrine disruption chemicals such as BPA and phthalates (mainly through effect on thyroid hormone receptors)
  • Possibly soy protein (thyroid hormone receptor effect)
  • Consider chronic herpes simplex infection as a cause (recurrent oral or genital herpes)


If you are in a hole then stop digging. First try to get a diagnosis as to why you are losing your hair. If it was an acute event like a large weight loss then it will take time to recover, typically six months to feel your hair is returning to normal. If the loss is due to medication you will need to change your medicine. Get checked out for iron deficiency if you are a woman. Consider a blood test for thyroid function. Combatting the effects of chronic conditions is more difficult.

Most people tend to make a full recovery. Some have more chronic problems. Women in this situation need to consistently get their ferritin measure of iron stores close to 70 (not the usual level of 20) in order to improve. Adequate protein intake is important although remember whey protein and soy protein have negative hormone effects of the hair. Pea protein is best if you supplement with protein powder. A dose of one gram of protein per kilogram of body weight will accelerate hair regrowth. High dose omega three supplements will do the same (over 400mg DHA).

Stop smoking if you smoke.

A multivitamin and multi mineral directed towards hair growth will probably help. There are supplements for which there is some evidence they may help hair growth; zinc, biotin, silica in particular.

A course of topical minoxidil treatment can accelerate recovery from acute TE.

Work to lower the cortisol excess brought on by stress.

Chronic TE is a very exasperating condition to manage. You can do everything well and then some new event, like an illness or recurrent iron deficiency, can occur and you are back to square one. If this is you and you find things have reverted to heavy shedding then start at the top of this section again and work your way down.