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If there is one certainty when discussing hair loss it is that it can affect anyone, irrespective of age, ethnicity or gender, and it is much more common than you may think.

The causes and reasons for hair loss are incredibly varied and for those of us suffering from losing our locks, it can be very distressing to sift through all the scary information online to find out exactly what’s going on. Fear not, we’re here to help with this list of the most common reasons why we lose our hair.

Whether you’re just starting to notice thinning, you have been suffering for a while, or you want to prevent losing your hair to start with, we'll cover some of the most common causes of hair loss and get you clued up on the facts. 

Broadly speaking, the most common causes for hair loss can be attributed to one of three categories; genetics, medically related hair loss, and those caused by certain lifestyle choices.

If you want to know more about your hair growth, take a look at our article on the hair cycle to help understand the remarkable journey your hair takes and how your hair grows.


Now we move on to the causes of hair loss, so let's tackle the most common form first -  Androgenetic Alopecia aka Hereditary Hair Loss or Male Pattern Baldness.


For a lot of hair loss sufferers, unfortunately, it’s down to genetics. In fact, the most common of all causes of hair loss is Androgenetic Alopecia, often known as patterned baldness. You may have heard of male pattern baldness, but women can also experience hereditary thinning and hair loss too.

Androgenetic Alopecia affects about 50% of men over the age of 50, and about 50% of women over the age of 65 accordingly to the British Association of Hair Restoration Surgery (BAHRS), who go on to say that those suffering from Androgenetic Alopecia are actually inheriting hair follicles with a genetic sensitivity to Dihydrotestosterone (DHT). 

However, there are some big differences between male and female counterparts. While many men start losing their hair around the hairline and crown (resulting in a receding hairline and a bald patch), female pattern baldness more commonly forms by slowing down the hair’s growing phase, shrinking the follicles and leading to thin, fine hair across the whole head, starting at the parting.

When discussing Androgenetic Alopecia with your doctor, they may often refer to one of the universal classification systems - The Norwood Scale (for men) or the Ludwig Scale (for women). While other scales are now in use, let’s look at what these two more common systems are and how they help classify the degree of your hair loss;


    The Hamilton-Norwood scale, more commonly known as the Norwood Scale, was first introduced in the 1950s by Dr Hamilton but later updated in the 1970s by Dr Norwood and is perhaps the most commonly used classification system for male pattern baldness.

    While hair loss can be unpredictable and sometimes a little confusing, the Norwood scale is broken down into 7 stages of patterned hair loss and can be used to depict how hair loss typically progresses in men with Androgenetic Alopecia. The scale is a helpful visual aid to understand what stage your hair loss may be at and also be useful to determine the types of treatments that may be more beneficial for you at each stage of the scale.

    STAGE 1

    This first stage in the Norwood scale is where you would be considered as having a full head of hair, with little to no visible signs of hair loss or receding hairline.

    STAGE 2

    At stage 2, you would be considered to be showing slight evidence of your hair receding but this would be regarded as barely noticeable.

    STAGE 3

    By stage 3, your hair loss is generally more noticeable and you typically see the hairline receding from the temple area giving the classic “M” shape to your hair.


    As above, this sub-classification also incorporates hair loss from the crown.  

    STAGE 4

    Stage 4 on the Norwood scale would be determined as significantly noticeable. At this stage, it would be apparent that you are experiencing hair loss

    STAGE 5

    We are now in the realm of what can be considered severe hairloss. By stage 5, there is likely to still be some hair covering the scalp but the hair continues to recede from the sides.

    STAGE 6

    With far more skin visible on the scalp at stage 6, by now you are likely to have hair remaining on your sides but the crown and hairline have joined across the scalp.

    STAGE 7

    In the final stage on the Norwood scale, at stage 7 there is little to no hair on the scalp. While hair remains at the side and back, any hair grown on the top would like to be very weak and thin.

    In addition to the 7 primary stages, there are also 4 class A patterns found in stages 2 through 5. These are less common but signify a more aggressive loss from the front of the hairline (ref: Bernstein Medical).


      As with the Hamilton-Norwood scale, the Ludwig Scale is a classification system designed to identify the degree of female pattern hair loss in 3 easy stages. Designed in 1977 by Dr. Ludwig as a method of classifying female hair loss according to a scale of severity, this scale is designed to assist in the diagnosis and treatment of female hair loss in three areas; the degree to which hair has already been lost, the potential for additional hair loss in the future, and the best course of treatment.

      The Ludwig scale is perhaps the most well-known scale, however, versions of this have been introduced since it was released, such as the Sinclair, Savin and Olsen Scale.

      Credit: https://en.wikipedia.org/wiki/Ludwig_scale
      GRADE 1

      Grade 1 on the Ludwig scale is typically identified as minimal thinning. At this stage, hair loss at this stage may go unnoticed by other people but appear and feel generally thinner to you.

      GRADE 2

      At grade 2, this could be considered more moderate hair loss. By this stage, you may notice a widening at the parting of your hair and a more moderate reduction in the thickness of your hair along with an increase in shedding.

      GRADE 3

      Often described as diffuse thinning, this type of hair loss creates a see-through appearance on the top of the scalp. This is the rarest, most severe type of hair loss for women and it’s difficult to mask with hairstyling techniques.


      Another form of hair loss, also known as spot baldness, Alopecia Areata is an unusual cause of hair loss in women that typically starts in the form of one or more small, smooth patches appearing. The condition is understood to be an autoimmune disorder, where something in the body triggers the immune system to suppress the hair follicles and stop them from growing.

      According to the American Academy of Dermatology Association, Alopecia Areata can begin at any age of your life. This form of alopecia is most commonly developed during childhood or teenage years and, while children demonstrate a greater risk of developing Alopecia Areata if their parent has had this in the past, around 50% will see their hair regrow within 12 months without the need for treatment

      Although no one is quite sure what causes these triggers, the hair can certainly regrow even after years of extensive hair loss. Unfortunately, due to its unpredictable nature, it can also fall out again. Alopecia Areata is occasionally associated with other medical problems that can also trigger hair loss, and more often than not the bald areas regrow their hair spontaneously over time according to the website Medicinenet.com.

      When discussing this type of hair loss, there are 3 main types of Alopecia Areata;


        This type of alopecia is identified by the presence of patchy spots, which can develop anywhere on the body. This includes not only the scalp but can also affect the beard area, your eyelashes and eyebrows, along with areas such as your armpits.


          As the name implies, this represents a total loss of hair on the scalp, leaving it bald.


            The rarest of the three forms of Alopecia mentioned but signifies a complete loss of hair across the entire body.


            The Coeliac UK website describes this as a “genetically linked condition through the Human Leukocyte Antigen (HLA) gene system”. This autoimmune disorder causes the body's immune system to attack tissues found in the gut when the presence of the protein in gluten (wheat, rye, barley) is detected. As this damage and inflammation can lead to the body being unable to properly absorb nutrients,  it has been linked to hair loss due to nutritional deficiencies. As the presence of one autoimmune disorder can also increase the chances of developing a second, there have been links reported in a 1995 paper between Alopecia Areata and Celiac Disease.


            Anaemia is a deficiency of either iron or Vitamin B12 and develops when your blood lacks enough red blood cells and often results in fatigue, shortness of breath and can cause hair loss. The condition essentially sends your body into ‘survival mode’ and channels all the oxygen to support vital organs, limiting the oxygen going to the functions that maintain healthy hair.

            In the case of Iron deficiency anaemia, there are some studies that show a correlation between iron deficiency and hair loss, perhaps due to the role in which iron plays in cell growth. However in an article published back in 2018 for Medical News Today, referencing a research paper conducted by the Journal of the American Academy of Dermatology “determined that there is not enough evidence to say for sure that iron deficiency anaemia can cause hair loss in men or women. While some studies have found that people experiencing hair loss were deficient in iron, there is little evidence to suggest that an iron deficiency is the cause.”


            Severe or prolonged cases of hypothyroidism & hyperthyroidism have been noted as causes of hair loss, as referenced by the British Thyroid Foundation. According to their website, the hair loss experienced is often blamed on the medication used to treat the thyroid condition, however, as the hair loss is often apparent several months after the onset of thyroid disease this is incorrect and ceasing the treatment may actually worsen the hair loss experienced.

            Having said that, by their own admission, there are cases of diffused hair loss occurring when taking anti-thyroid drugs such as carbimazole and propylthiouracil.

            In most cases, people with hypo - and hyperthyroidism have autoimmune thyroid disease, which, as we have mentioned in Coeliac Disease, can lead to further autoimmune conditions such as Alopecia Areata. 


            Vitamin A is a fantastic and powerful antioxidant and should be a vital part of an everyday balanced diet. You will find that many hair and nail supplements, in particular, contain vitamin A as it is essential in supporting the maintenance of healthy hair, along with skin, nails and vital organs such as your liver and kidneys.

            Given that vitamin A is essential to healthy hair, it is no wonder that you also find this in many hair loss treatment products as beta-carotene (a form of vitamin A found in foods such as carrots, kale and sweet potato) has been shown in studies to be particularly beneficial to Alopecia Areata patients due to its anti-inflammatory properties.

            However, as with anything, this should be taken in moderation and too much vitamin A can have negative effects. In fact, the World Health Organisation advises that excessive vitamin A (Chronic Vitamin A toxicity) may produce hair loss and lead to Alopecia. So, in the case of Vitamin A, you can have too much of a good thing.


            Protein is another important part of a balanced diet, especially for your hair, after all as we have covered in other articles, your hair is primarily composed of the protein - keratin!

            Every cell in your body requires protein, so it vital to include an adequate amount of protein in your diet as this will help to ensure that your body has the necessary building material to strengthen and repair your hair. A sudden drop in protein can cause changes to how your body prioritises allocating this macronutrient which can lead to your body diverting this from hair growth to conserve this for more essential body functions

            The American Hair Loss council advise that this is something you need to consider when making the choice to adopt a vegan lifestyle, as hair loss is something that can often be experienced unless you ensure you include protein-rich. foods such as quinoa, lentils, black beans and Chai seeds


            Some cancer treatments such as chemotherapy are well-documented to lead to hair loss amongst patients and can feel devastating for those already suffering from the disease. It’s a common misconception that cancer causes hair loss, but in reality, it’s the treatments that are to blame. The NHS advise that different types of chemotherapy drugs will demonstrate varying effects, with some causing only partial loss or thinning while others such as radiotherapy causing hair loss only in the area where treatment is focused.

            Chemo drugs are incredibly powerful for attacking cancer cells, but they can also harm other growing cells in your body, including your hair follicles. Because of the increased risk of hair loss, it is often advised that you plan for this and charities such as Look Good Feel Better (LGFB) can provide support and advice on wigs, along with skincare and make-up workshops.


            PCOS is a common hormone disorder that can display a range of symptoms including excess facial and body hair (known as hirsutism), weight gain, and fatigue. However, in some cases, it can also cause hair loss in women. 

            As written by Healthline, the medically reviewed US website, this disorder can result in the production of excess male hormones (androgens) that are produced naturally in the female body, known as virilization. This condition can result in decreased hair growth on your scalp for those with genetically sensitive hair follicles, much in the same way as we discussed earlier with Female Pattern Hair Loss (Andorgentieic Alopecia).


            Trichotillomania is considered a mental health condition, classified under Obsessive-Compulsive and Related Disorders, characterised by irresistible urges to pull out hair and more common in teenagers and young adults (NHS). For people with trichotillomania, hair pulling can be either focused, where they pull their hair intentionally to relieve tension or distress or automatic, where they pull their hair without even realizing they're doing it, such as when they're bored, reading or watching TV.

            Whatever the reason, it's not hard to imagine that this can contribute to long term hair loss, especially where this is focused on a particular area.


            Lupus is a chronic autoimmune disease that can damage any part of the body, and Lupus UK advises that there are two forms of hair loss that can occur in people with lupus. They are;

            • Discoid Lupus Erythematosus (DLE) or scaring alopecia, producing an area of permanent hair loss or
            • Systemic Lupus Erythematosus (SLE), which is the most common form and “non-scarring”. This usually consists of thinning of the hair and is not necessarily permanent.


            Skin conditions on the scalp can commonly cause hair loss, including dandruff and scalp psoriasis. Both cause itchy, inflamed skin on the scalp that can lead to intense and prolonged scratching. This scratching can damage the hair follicle and cause breakage to the strands, resulting in increased fall out.


            This rare, inflammatory condition results in patchy, permanent hair loss on the scalp with the British Association of Dermatology stating that it is between 2 and 5 times more common in women than it is in men with the commonest age of onset being in the mid-40s.

            Although the exact cause of lichen planopilaris is still unknown, it destroys the hair follicle and then replaces it with scarring, resulting in permanent hair loss and is linked to the more commonly known skin condition lichen planus.


            This one is a cause of hair loss that we can actively prevent! Traction alopecia is a result of external stresses that we put on our hair: think overuse of extensions, weaves, tight ponytails, and braids. Yep, those beautifully long extensions can cause untold havoc on our locks! Anything that pulls the hair can damage the root and lead to scarring and permanent hair loss.


            Stress can be another common reason for hair loss, as extreme and prolonged stress can cause an increase in the production of adrenaline which eventually raises your body’s testosterone level. As we have covered in our section on Androgenetic Alopecia, higher levels of testosterone can be a catalyst for hair loss if it is converted to DHT.

            WEIGHT LOSS

            Rapid weight loss and restrictive dieting can be an unexpected cause of hair loss and have been linked to a condition known as Acute Telogen Effluvium (TE for short). In fact, there are studies from as far back as the 1970s on the NCBI’s PubMed site that link crash dieting and hair loss, which is in keeping with the documented studies relating to nutritional deficiencies and hair loss. 


            While there are legitimate medical uses for anabolic steroids, such as a prescription to assist with certain types of anaemia in men or to assist those who do not produce sufficient testosterone on their own, Anabolic steroids are perhaps commonly associated with their illegal uses as performance enhancers (NHS).

            Many sources cite hair loss, along with other potentially dangerous medical conditions, as a common side effect when using anabolic steroids, with The Hair Loss Doctors site  mentioning the accelerated production of DHT (one of the primary hormones involved in male pattern baldness) when using this type of steroid.


            Perhaps one of the most common causes of hair loss amongst new mothers, postpartum alopecia generally a few months after giving birth, as stated by the AAD and is not true hair loss. When pregnant, your body goes through a lot of hormonal changes which can also affect your hair due to the increased levels of estrogen produced. These higher levels of estrogen increase the amount of time that the hair remains in the growth phase, resulting in less shedding and often thicker-looking hair.

            Conversely, post pregnancy, the temporarily retained hair sheds as its anagen phase comes to an end and is caused by the falling levels of estrogen in your body.


            Various sources on the internet indicate and attribute birth control pills and hair loss hair, theorising that the hormones contained with them cause the hair to move from the growing anagen phase to the resting phase too soon and for a longer period of time. This particular type of hair loss has been mentioned earlier in the article - Telogen Effluvium - and if hair loss is something that you are aware runs in the family, then contraceptive pills could speed up the hair loss process.

            However, certain birth control pills may also benefit some women with hair loss, with the ISHRS suggesting those containing drospirenone may be helpful.


            Although this is not an exhaustive list, this should hopefully help show you that there are many causes of both long-term and temporary hair loss. With such a complicated subject, it is important to take the time to speak to a medical professional to understand what may be causing your own loss before looking at any potential treatment options.


            Why not check out our other articles;


            While our aim is to provide you with up-to-date and relevant information, drugs affect each person differently. As such we can not guarantee that this information includes all possible side effects and this information is not a substitute for medical advice. Always discuss treatment options and possible side effects with a healthcare professional who knows your specific medical history.