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Anagen Effluvium: Symptoms, Causes and Treatments

Katelyn Brenner FNP

Reviewed by Katelyn Hagerty, FNP

Written by Rachel Sacks

Published 02/18/2021

Updated 07/31/2023

Cool fact: When you’re born, you’ve already developed all the hair follicles you’ll ever have. So you’ve already accomplished something barely out of the womb.

While you can’t change the number of follicles on your head, your hair will go through different phases of growth, with new strands of hair almost constantly growing in at some point.

Each phase follows its own timeline, which is affected by numerous factors, including a person’s age, genetics, nutrition and overall health.

Beyond lifestyle choices, some uncontrollable factors can affect hair growth. For instance, exposure to toxins or chemical medications can lead to a type of hair loss known as anagen effluvium.

Below, we’ll cover everything you should know about this kind of hair loss, including anagen effluvium symptoms and whether the condition is reversible. We’ll also go over a few science-backed anagen effluvium treatments.

Anagen effluvium is triggered by stressors like severe infection or harsh medical treatments, such as chemotherapy. It may cause you to lose a significant number of hairs all at once, resulting in diffuse hair loss.

There are also certain toxins that cause hair loss, most likely anagen effluvium.

To better understand how anagen effluvium happens, let’s look at how hair grows. Every single hair on your head is made up of two main parts. The follicle underneath the skin is made up of an inner and outer root sheath from which the hair shaft grows (produced from the hair bulb, which is part of the follicle).

Each hair goes through a predictable hair growth cycle consisting of three phases: the anagen phase (growth), the catagen phase (transitional) and the telogen phase (resting). At any given time, 85 to 90 percent of hair follicles are in the growth or anagen phase.

Exposure to toxins or certain chemicals can affect the anagen hairs (those in the growth stage). Effluvium is a term used to describe active hair loss of more than 100 hairs per day over a period of two to four weeks. Hence the name, anagen effluvium — or diffuse alopecia, when the hair loss is all over the body.

Anagen effluvium is different from one of the most common hair loss types, telogen effluvium. Telogen effluvium is hair loss caused by stress or a shock to the system that results in excessive hair shedding.

When exposed to stress, normal anagen hairs skip right to being telogen hairs, where they stop growing for one to six months.

So, how do you know if you’re dealing with anagen effluvium? Besides talking to your healthcare provider for a diagnosis, you can look out for these anagen effluvium symptoms:

  • Hair loss that starts at the crown and sides of the head

  • Diffuse thinning of scalp hairs (or thinning of hair on the scalp)

  • Hair loss that occurs one to four weeks after being exposed to the toxin or chemicals that caused it

  • Nonscarring alopecia with round or oval bald patches

  • The hair shaft (individual strands) breaks easily

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One of the big differences between telogen effluvium and anagen effluvium? The causes of each hair disorder.

Telogen effluvium is typically caused by internal changes to the body, such as stress, diet, malnutrition, hormonal changes or an autoimmune condition. Meanwhile, the most common causes of anagen effluvium are external stressors, like medication, chemotherapy or toxic metal exposure.

Common causes of anagen effluvium include:

  • Chemotherapy (anagen effluvium is also known as chemotherapy-induced alopecia)

  • Autoimmune conditions (alopecia areata)

  • Exposure to toxic heavy metals (if you work in an industrial environment)

Chemotherapy-induced alopecia is the most common form of anagen effluvium. But rare causes can include radiation exposure, trauma, malnutrition or certain medications.

Anagen effluvium has a few specific common causes. So if you’re not currently being exposed to chemotherapeutic agents or heavy metals (besides rock music) but are losing hair left and right, there are other causes of hair loss you can look into.

Your healthcare provider or dermatology clinician may do a differential diagnosis to figure out what’s going on. For example, they might do a hair-pull test to rule out other hair loss types, such as androgenetic alopecia, dermatitis, or other causes like thyroid disease. Although not entirely necessary, a healthcare provider might do a biopsy to rule out telogen effluvium as the cause of hair loss.

While any type of hair loss is alarming, you’ll be glad to know that if you’re dealing with anagen effluvium, you’re most likely only dealing with temporary hair loss.

This is often because once you’re no longer exposed to the chemicals causing the hair loss, your hair will start growing back (although there are cases where anagen effluvium hair loss is permanent).

Hair regrowth typically starts one to three months after you finish chemotherapy or are no longer exposed to the toxins that caused it.

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Many people experience hair regrowth within a few months of completing chemotherapy or radiation treatment. But generally speaking, anagen effluvium treatment is aimed at limiting the amount of time the patient suffers from hair loss.

The only treatment options supported by research to prevent or reduce the duration of anagen effluvium are scalp cooling therapy and topical minoxidil. Here’s what to know.

Scalp Cooling During Chemotherapy

A method to prevent hair loss during chemotherapy, scalp cooling — or scalp hypothermia — has been found to help prevent hair loss in patients undergoing chemotherapy.

FDA-approved for chemotherapy-induced alopecia, this treatment works by restricting blood vessels in the scalp to reduce blood flow, limiting the amount of chemo medication that reaches the hair follicles.

This treatment can be accomplished using ice packs, cooling caps or a scalp cooling system. Side effects included patient discomfort from the heavy caps and headaches.

In one study involving 142 women with breast cancer, more than 50 percent of patients who received scalp cooling kept most or all their hair.


A topical medication approved by the FDA for treating hair loss, minoxidil is available in foam and liquid forms, as well as in 2% and 5% concentrations. We offer both a minoxidil foam and a liquid minoxidil solution.

Minoxidil is thought to improve hair growth by triggering the hair follicles to enter the growth phase early. Keep in mind, though, that minoxidil may take several months to be noticeable, so patience is key. Still, minoxidil is thought to reduce baldness by an average of 50 days.

There are more ways to restart hair growth, from supplements to hair transplants and more. Our guide on how to reactivate hair follicles has details.

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Dealing with hair loss is tough. It can rock your confidence and affect how you feel about yourself if your hair is falling out. If you’re dealing with anagen effluvium, knowing the signs, causes and potential remedies can help you cope.

Here’s what to keep in mind:

  • Anagen effluvium is a type of hair loss often caused by harsh treatments or medications. It can result in diffuse hair loss, thinning or patchy hair.

  • Other anagen effluvium symptoms include hair loss at the crown and sides of the head, hair breakage and hair loss that doesn’t stop when you’re no longer exposed to the toxins or medications that caused it.

  • While the most common cause is chemotherapy, anagen effluvium can also happen if you’re exposed to heavy metals, radiation, severe infection or extreme trauma.

  • Fortunately, anagen effluvium is temporary, and hair typically grows back when exposure to harsh treatments is over. There are two treatment options to prevent hair loss: scalp cooling (if you’re undergoing chemotherapy) and minoxidil.

While these two anagen effluvium treatments are proven effective, you can explore other hair loss treatments with a healthcare provider or dermatologist.

You can also read our guide on how to keep your confidence when losing your hair or explore online therapy to cope with hair loss.

7 Sources

  1. Saleh, D., Nassereddin, A., & Cook, C. (2023). Anagen Effluvium. StatPearls Publishing. Retrieved from
  2. Hoover, E., Alhajj, M., & Flores, J. L. (2023). Physiology, Hair. StatPearls Publishing. Retrieved from
  3. Kanwar, A.J., Narang, T. (2013). Anagen effluvium. Indian J Dermatol Venereol Leprol. 79(5) 604-612. Retrieved from
  4. Qi, J., & Garza, L. A. (2014). An overview of alopecias. Cold Spring Harbor perspectives in medicine, 4(3), a013615. Retrieved from
  5. Wikramanayake, T.C., Haberland, N.I., Akhundlu, A., Nieves, A.L., Miteva, M. (2023). Prevention and Treatment of Chemotherapy-Induced Alopecia: What Is Available and What Is Coming? Current Oncology, 30(4), 3609-3626. Retrieved from
  6. Nangia, J., Wang, T., Osborne, C., et al. (2017). Effect of a Scalp Cooling Device on Alopecia in Women Undergoing Chemotherapy for Breast Cancer: The SCALP Randomized Clinical Trial. JAMA. 317(6), 596–605. Retrieved from
  7. Badri, T., Nessel, T. A., & D, D. K. (2023). Minoxidil. StatPearls Publishing. Retrieved from
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This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.