Hair loss causes: myths vs. facts and what you can do about it
Hair loss can be extremely frustrating, but the causes of hair loss may surprise you. We look at seven myths and facts about hair loss in men and women.
Noticing more hair than usual in your brush or plughole can be unsettling. While losing some hair every day is a normal part of the hair growth cycle, excessive shedding or visible thinning can be a sign that something internally is out of balance.
This guide will help separate common hair-loss myths from facts, explaining how nutritional deficiencies, hormone imbalances, physical illness, emotional stress and genetics may contribute to hair loss. It also looks at what blood tests such as our Hair Loss Blood Test can tell you and what steps you can take to find the underlying cause.
Myth 1: Magnesium supplements cure hair loss
There is limited evidence linking magnesium deficiency specifically to hair loss compared with nutrients such as iron, zinc, and vitamin D [5]. If someone is deficient in magnesium, correcting that deficiency may be helpful, but taking magnesium supplements is not a proven cure for hair loss.
Nutritional factors that can affect hair loss include:
- Iron: Low ferritin (Stored iron) is one of the common nutritional factors linked with hair loss, particularly in women. A healthy level of ferritin should aim to be 70 µg/L or above.
- Vitamin D: Plays a role in hair follicle function. A normal level of vitamin D should be nmol/L and above
- Zinc: Is essential for hair tissue growth and repair
- Vitamin B12 and folate: Are important for red blood cell production, which carries oxygen to the scalp and follicles.
Fact: your hair relies on a steady supply of nutrients to grow. Deficiencies in certain nutrients can contribute to thinning and shedding, so identifying a genuine deficiency is more useful than guessing which supplement you need [5].
Myth 2: It’s not normal to lose hair every day
Shedding around 50 to 100 hairs per day can be perfectly normal and is part of the natural hair-growth cycle. Each hair follicle works through its own cycle, moving through a growth phase (anagen), transitional phase (catagen), resting phase (telogen) and shedding phase (exogen).
Fact: It is when this cycle is disrupted that you may notice more hair falling out than is growing back. A sudden increase in shedding, visible thinning, or hair loss that is persistent or concerning is worth discussing with a healthcare professional [3].
Myth 3: Hair loss is only caused by genetics
Genetics are an important cause of hair loss, but they are not the only one. Hair loss can have several contributing factors, and these can overlap. [4]
Factors that contribute to hair loss include:
- Genetic factors, including male and female pattern baldness
- Physical or emotional stress, which can trigger telogen effluvium
- Nutritional gaps, including low iron, vitamin D or zinc
- Hormonal imbalances, including thyroid disease, PCOS or menopause
- Medications, which can sometimes cause hair loss as a side effect.
Fact: The causes of hair loss are varied and often overlap. They include genetic, physical, nutritional, hormonal and medication-related factors.
Myth 4: Only severe stress causes hair loss
Stress can contribute to hair loss, but significant physical or emotional changes can also trigger a type of temporary shedding called telogen effluvium. Triggers can include illness, surgery, child-birth, COVID-19, rapid weight loss and significant emotional stress. [3]
Fact: The timing can be surprising: hair shedding often starts around two to three months after the trigger rather than immediately. By the time you notice it, the original event may have passed. Telogen effluvium is usually temporary and may improve as the body recovers, although ongoing stress or another underlying factor can prolong shedding.
Myth 5: Follicle-stimulating hormone (FSH) causes hair loss
The name can be misleading. Follicle-stimulating hormone (FSH) refers to ovarian follicles and reproductive function; it does not refer to hair follicles. Hair loss can, however, be associated with other hormonal changes and conditions.
Fact: Hormonal changes can contribute to hair thinning, but FSH itself should not be confused with the hair follicle. High follicle-stimulating hormone can be linked to menopause, which can cause hair loss. An underactive or overactive thyroid can disrupt the hair-growth cycle and cause diffuse thinning. In women, conditions such as PCOS can involve higher androgen levels and may contribute to thinning hair. Hormonal changes during menopause, including falling oestrogen levels, can also be associated with slower growth and increased shedding. In men, changes in androgen levels and some treatments, including testosterone replacement therapy, can also be relevant when assessing hair loss [2][4].
Myth 6: Only men go bald with age – it’s just part of getting older
Hair loss can affect anyone, and getting older does not automatically mean you will lose your hair. Genetic hair loss can affect both men and women, although the pattern and progression can differ. [2]
Fact: Genetic pattern hair loss is influenced by genetics and hormones. Dihydrotestosterone (DHT) is involved in male pattern hair loss, while inherited sensitivity to androgens can contribute to pattern hair loss in both sexes. Genetics can come from either side of the family, and pattern hair loss is often progressive rather than simply being a normal consequence of ageing.
Myth 7: Hair loss is always permanent
Not all hair loss is permanent. Whether hair grows back depends largely on what is causing the hair loss.
Fact: Some common forms of hair loss are temporary or reversible, while others can be progressive or become permanent. [6] Some types of alopecia can be scarring, which means the hair may not recover, so it is important to see your doctor urgently to diagnose the condition and discuss treatments if you think you have alopecia.
| Type | What it looks like | Is it permanent? |
| Pattern hair loss | Gradual thinning | Usually progressive |
| Telogen effluvium | Sudden shedding | Usually temporary |
| Alopecia areata | Patchy bald spots | Often reversible |
| Traction alopecia | Hairline thinning | Can become permanent |
How can I find out what’s causing my hair loss?
The first step is to look for the underlying cause rather than treating hair loss as one single condition. A GP can help assess your symptoms and medical history and decide whether further investigation is needed. You may choose to take a private blood test, such as our Hair Loss Blood Test, so you can bring your results to you GP for further discussion. Depending on what is suspected, you may also be referred to an appropriate specialist, such as a dermatologist or trichologist [1].
Some people may also choose private assessment if they want to explore their symptoms sooner. Whatever route you take, the most useful approach is one that considers the pattern of hair loss alongside possible nutritional, hormonal, physical and genetic factors.
Can a blood test diagnose hair loss?
Blood tests do not diagnose hair loss itself. But, they can help identify underlying contributors that may be driving shedding or thinning.
Depending on your symptoms and circumstances, there may be different tests to take.
These include:
- Iron and ferritin – to check for iron deficiency
- Vitamin D – to identify a common nutritional deficiency
- Vitamin B12 and folate – to assess levels important for cellular function and red blood cell production
- Zinc – an essential mineral for tissue repair
- Thyroid function – to assess whether your thyroid is working correctly
- Hormones – including oestrogen, testosterone or other androgens where appropriate.
Identifying a nutritional or hormonal contributor can help guide the next steps, rather than relying on supplements or treatments without knowing what is causing the hair loss.
What are the best treatments for hair loss?
The best treatment depends on the cause. If hair loss is linked to a nutritional deficiency, correcting the deficiency may help. If a thyroid disorder or another hormonal issue is contributing, treating the underlying condition may improve the hair-growth cycle.
Other forms of hair loss may need different approaches, particularly genetic pattern hair loss or conditions such as alopecia areata. This is why identifying the likely cause is an important first step before deciding on treatment.
Frequently asked questions
Is hair loss permanent?
It depends on the cause. Genetic pattern baldness is progressive, while temporary forms such as telogen effluvium are often reversible.
Can low iron cause hair loss?
Yes. Iron deficiency, particularly low ferritin, is one of the nutritional factors linked with hair loss and can be treatable.
Can stress cause hair loss?
Yes. Physical or emotional stress can trigger telogen effluvium, with shedding often beginning around two or three months after the trigger.
How long does it take for hair to grow back?
Once the underlying trigger is removed, it can take around three to six months to see noticeable new growth [6].
Can low magnesium cause hair loss?
The evidence linking magnesium deficiency to hair loss is limited compared with nutrients such as iron, zinc and vitamin D [5].
References
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Imperial College Healthcare NHS Trust (2026) Hair disorders. Available at: https://www.imperial.nhs.uk/our-services/dermatology/hair-disorders (Accessed: 11 August 2026).
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International Society of Hair Restoration Surgery (2013) Hair loss myths. Available at: https://ishrs.org/hair-loss-myths/ (Accessed: 11 August 2026).
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Webdoctor.ie (2023) Hair thinning | Hair loss causes | Hair falling out causes. Available at: https://www.webdoctor.ie/male-hair-loss-treatment/thinning-hair-causes/ (Accessed: 11 August 2026).
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Wise Center for Plastic Surgery (2025) 10 Surprising Facts about Hair Loss Causes of Hair Loss. Available at: https://www.drwise.com/blog/facts-about-hair-loss/ (Accessed: 11 August 2026).
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Cleveland Clinic (2026) The Best Vitamins and Supplements for Hair Growth. Available at: https://health.clevelandclinic.org/the-best-vitamins-supplements-and-products-for-healthier-hair?utm_campaign=cc+tweets&utm_medium=social&utm_source=twitter (Accessed: 11 August, 2026).
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Cleveland Clinic (2025) How to Make Your Hair Grow Faster. Available at: https://health.clevelandclinic.org/is-there-any-way-to-make-your-hair-grow-faster?utm_medium=social&utm_source=twitter&utm_campaign=cc+tweets (Accessed: 11 August, 2026).