What Is Anagen Effluvium

Do you suffer from hair loss, or have you ever wondered why some people may suffer from excessive hair loss? This article aims to address these questions and provide insight into some options for treatment and management. 


Anagen effluvium is a condition involving hair loss during the active phase, also known as the anagen phase, of the hair cycle. All the hairs we have on our bodies go through recurrent hair cycles where they grow, fall out and re-generate. During the anagen phase, we would expect most hair to grow within this time. Some people, unfortunately, lose more hair than others for various reasons, which we will discuss in more detail. Some of the main reasons for hair loss include nutritional deficiencies, autoimmune disorders, medications and chemotherapy. Understandably, losing hair can be distressing and affect self-image and emotional well-being and so understanding the process of anagen effluvium allows for earlier diagnosis, prevention and effective treatment. 

The hair growth cycle 

The hair growth cycle describes the life cycle that hair goes through, which is a natural process and varies from person to person; many factors influence the hair growth cycle, such as hormones, stress, nutrition, age and sleep.1 

Phases of hair growth 

The cycle consists of 3 consecutive stages: anagen, catagen and telogen2

  1. Anagen - the phase in the cycle where hair growth is most prominent, duration varies between people but averages 2-7 years. 
  1. Catagen - a transitional stage between the active and resting phase, this usually lasts a few weeks. 
  1. Telogen - the resting phase, where no new hair growth occurs and shedding of the hair strand occurs. Typically lasts 2-4 months. 

Causes of anagen effluvium 

  • Chemotherapy and radiation therapy - Anagen effluvium can present after a few days to weeks after commencing chemotherapy. However, hair growth usually returns once chemotherapy is stopped3
  • Medications and toxins - other toxins such as gold, colchicine, arsenic, bismuth and boric acid can cause anagen effluvium4
  • Nutritional deficiencies - Lacking vitamins and minerals can affect how much hair you lose. Particularly vitamin B12, folate and biotin 
  • Autoimmune disorders - certain autoimmune diseases such as those of the skin (like pemphigus vulgaris) or alopecia areata4

Signs and Symptoms 

Anagen effluvium may be suspected in people who suddenly have rapid scalp hair loss or shedding. Occasionally, people will also suffer shedding from other areas of body hair. The rate of hair loss may differ from person to person. There should be no signs of inflammation or redness on the scalp.3 Hair loss in anagen effluvium is often rapid, resulting in lots of hair lost over a period of days.


History and examination

In order to diagnose anagen effluvium, a doctor will take a comprehensive history to determine what your symptoms are and whether you have any predisposing factors. A doctor would then examine your scalp, looking for the key hallmark of anagen effluvium, which is a tapered fracture of the hair shaft.3 This means that the end of the shaft of hair looks thinner at the end than the rest of the hair, creating a tapered effect. Other forms of hair loss will cause a different appearance to the hair shaft. Although a doctor may be able to see this with the naked eye, occasionally, looking at the hair under the microscope may be necessary or more useful. This helps to determine whether a person may have anagen effluvium or a similar cause of hair loss, known as telogen effluvium, where hair is lost during the telogen phase of the hair cycle. During telogen effluvium, the hair has a more rounded edge at the end.4 

Scalp biopsy

If further investigation is required, a scalp biopsy may be done; this involves taking a sample of skin from your scalp in order to look at the hairs in more detail. In anagen effluvium, it would be expected that the hairs would have a normal anagen-to-telogen ratio, with less than 15% of hair follicles in the telogen phase.3 

Blood tests 

Finally, in order to fully determine the cause of hair loss, it may be necessary to undertake blood tests to determine if there are any nutritional deficiencies or autoimmune diseases that may be causing the hair loss. 

Differential diagnosis 

Other diagnoses that may be confused with anagen effluvium include the previously alluded to telogen effluvium, but also other diagnoses such as trichotillomania and androgenetic alopecia .3 Treatment for these differ from anagen effluvium, hence, why it is important to have an examination and appropriate diagnosis. 


Discontinuation of causative factors 

If any causative factors are contributing to hair loss, such as chemotherapy, then discontinuation would allow for the management of anagen effluvium. However, this is of course not a suitable option for everyone, and is an unfortunate side effect of such medications.

Supportive hair care or medical interventions 

If a cause has been determined via blood tests, such as vitamin deficiency, then supplementation can help with reducing hair loss. However, in some people, they may decide to use medications in order to help with hair growth. It is important to note that no treatment is 100% effective, and some people may need to trial a few different medications in order to figure out what works for them. Some examples of medications include: 

  • Finasteride and minoxidil - usually used for hair loss in males, who experience the typical male pattern baldness. Although minoxidil can be used in males and females, finasteride should only be used in males 
  • Steroid injections or creams into areas of bald patches to help stimulate the hair follicle 
  • Hair transplant - hair is taken from another area of the head and transplanted into the area of the thinning patches of hair 
  • Tattooing - adding a tattoo to the area of balding
  • Light treatment - using UV light on the bald patches to help stimulate hair growth5 

Some people may wish to wear a wig, which occasionally may be available on the NHS, deciding whether you want a synthetic or real-hair wig is an important decision. Synthetic wigs may be cheaper but do not last as long, whereas real hair wigs may look more natural and last longer, but are more costly. 

Of course, some people may wish to not have any treatment. Although anagen effluvium is not dangerous or painful, it can be distressing. Some people may, therefore, require emotional support. 


Most causes of anagen effluvium are reversible. For example, after discontinuation of chemotherapy, people with hair loss due to anagen effluvium are expected to fully recover within 3-6 months. Hair may, however, grow back slightly different to how it was previously e.g. different colour or texture.4 


In summary, anagen effluvium describes hair loss during the active phase of the hair cycle, where usually, the majority of hair growth would occur. This can be caused by a range of reasons, such as autoimmune disease, vitamin deficiency and medications. In order to diagnose anagen effluvium, a history and examination needs to be carried out by a doctor. Hairs that are lost due to anagen effluvium will have a tapered look. Although there are no treatments which are 100% effective for hair loss, avoiding the initial trigger, using creams or getting a hair transplant can be useful options for people suffering from hair loss. It is important to note that most cases are reversible, and hair growth will resume with discontinuation or treatment of the cause. If you are suffering with hair loss and are worried about anagen effluvium, it is important to visit your GP so that you can get an appropriate diagnosis and potential treatment if required. 


  • Natarelli N, Gahoonia N, Sivamani RK. Integrative and Mechanistic Approach to the Hair Growth Cycle and Hair Loss. J Clin Med 2023;12:893. https://doi.org/10.3390/jcm12030893.
  • Hoover E, Alhajj M, Flores JL. Physiology, Hair. StatPearls, Treasure Island (FL): StatPearls Publishing; 2023.
  • Saleh D, Nassereddin A, Cook C. Anagen Effluvium. StatPearls, Treasure Island (FL): StatPearls Publishing; 2023.
  • Anagen effluvium: Causes, Images, and Treatment — DermNet n.d. https://dermnetnz.org/topics/anagen-effluvium (accessed September 22, 2023).
  • Hair loss. NhsUk 2017. https://www.nhs.uk/conditions/hair-loss/ (accessed September 22, 2023).
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Erin Sell Erin Sell

I have a BSc in Biomedical Sciences from the University of Bath and an MSc Physician Associate Studies from the Hull York Medical School. I worked as a Physician Associate in an NHS GP surgery where I developed my clinical knowledge.

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