13 reasons you might be losing your hair – and what to do about them

Telegraph

23-05-2025

For many, hair loss begins subtly: a few extra strands lining the shower floor, or your hairbrush collecting a little more hair than normal. Perhaps you've noticed your parting seems wider, or you've spotted a shiny bald patch in the barber's mirror. For others, hair loss strikes suddenly and dramatically, appearing overnight, following illness, stress or bereavement.
However it makes itself known, losing hair – for both men and women – can be incredibly distressing, particularly when the cause remains something of a mystery. Yet, huge numbers experience it: in the UK, it's estimated that around eight million women experience hair loss, and androgenetic alopecia (male pattern baldness) affects around 85 per cent of men by the time they turn 50. Here, we explore the potential culprits and how best to tackle the problem.
1. It's genetic
It's thought that male pattern baldness (or androgenic alopecia) affects around two thirds of all men. 'While the exact cause isn't fully established, it's strongly linked to genetics and male hormones (if your father and/or other male family members on either side are bald,there's a good chance you will be too),' explains Dr Bessam Farjo, a hair transplant surgeon at the Farjo Hair Institute.
It can start in your early 20s, often beginning with gradual hair loss at the temples and a receding hairline (when the hairline moves back on the head) followed by all-over thinning and often, a growing bald spot on the crown. Genetic hair loss can also occur in women.
There are a huge range of options if you're worried about going bald. 'Treatments range from medications like minoxidil or finasteride [a medication typically used to treat an enlarged prostate]. In areas of very advanced hair loss or where the hair is almost all gone, a hair transplant might be recommended.'
2. You're going through the menopause
For anyone transitioning to perimenopause or menopause, concerns about hair might be low down the list. But the hormonal changes that take place can lead to hair loss, explains Dr Farjo.
'In perimenopause, women begin to produce less oestrogen which supports hair growth, amplifying the effect of testosterone, which women also produce a small amount of. When oestrogen stops being produced however, the testosterone starts to exert similar effects to the ones men experience when they lose hair.' In other words, hair loss on the top of the head, around the hairline and into the crown, with the scalp becoming more visible.
The solution? ' HRT [hormone replacement therapy] has the potential to help, since it helps restore a female hormone presence, though it depends on how far the hair loss has gone,' says Dr Farjo. 'Another option is minoxidil in either liquid, foam or tablet form, though the latter is best for those sensitive to topical application.'
3. You're stressed or anxious
Compared to hormonal hair loss (which typically shows up as a general thinning on top of the head and around the crown), hair loss as a result of stress, anxiety or trauma (things like bereavement, job loss or divorce) can cause a condition called telogen effluvium, which results in 'diffuse thinning' in an even pattern across the whole head. It can also happen following serious illness, or a major operation. 'The shock triggers the body into shedding a much higher percentage of hairs than normal and is usually evident around three to four months after the traumatic event has taken place,' explains Dr Farjo.
'While we don't fully understand the specifics of predisposition to hair loss, there are likely other factors contributing too, like nutritional issues or metabolic disease, which mean if you then encounter a stressful situation it has the potential to cause hair loss.' As with postpartum hair loss, Dr Farjo suggests a wait-and-see approach – it should rectify itself, once the stress has subsided.
4. You're low in iron
You wouldn't be alone here. Iron deficiencies are pretty common (particularly for women, thanks to monthly cycles). In 2023-2024, hospital admissions as a result of lack of iron were up 11 per cent from the previous year, almost 10 times the 20,396 admissions for the same thing in 1998-99. And while your GP might consider your iron levels 'satisfactory' (as revealed by a blood test), they may be much lower than the levels needed for hair growth.
'Hair is a more sensitive marker for anaemia than other tissues in the body, meaning you notice effects on hair before you notice them on the rest of your body,' says Dr Farjo. 'While your ferritin levels (a protein that reflects the body's iron stores) in a blood test need to be 40ug/L or above (below which it could affect your health), I'd recommend they're at least 70 because hair needs higher levels than the rest of your body.'
As well as replenishing your iron levels through diet, by tucking into iron-rich foods such as red meat, beans, nuts, dried fruit and spinach, supplements may be worth investigating. It's important to assess your levels via a blood test first, available via your GP, before taking iron supplements, since they may already be within range. Excess iron can lead to organ damage.
5. You're experiencing thyroid problems
One in 20 people in the UK have a thyroid problem, most commonly hypothyroidism (an underactive thyroid) or hyperthyroidism (an overactive thyroid), with women being six times more likely to suffer from thyroid disorders. Both types of thyroid condition can impact hair, explains Dr Farjo. 'An underactive thyroid is more commonly associated with hair loss, but an overactive thyroid can also affect not only hair loss but the quality of hair, with people complaining of straw-like, brittle hair. It's down to an imbalance of thyroid hormone which disturbs the cycle of the hair [the typical growing, resting and shedding cycle].'
Hair loss tends to be all-over thinning and is usually noticed more commonly in women. 'That could be in part because women typically have more visible, longer hair so hair loss has more of an impact visually. Because men more commonly experience genetic hair loss, hair loss thanks to thyroid issues is usually overlooked and diagnosed as male pattern balding alone. It's why it's important to thoroughly explore someone's medical background as there are often several causes contributing.'
The good news is, this type of hair loss is usually reversible, once thyroid issues have been rectified (usually with medication).
6. You have PCOS
Some medical conditions can, unfortunately, cause hair loss. One of the most common in women is polycystic ovary syndrome (PCOS). 'PCOS is often at the forefront of my mind when presented with a young woman losing hair, especially if the loss follows a male pattern of balding and they've noticed hair growth in places you don't expect to see in women (face, chest or stomach, for example),' says Dr Farjo.
'I'd always recommend seeking a gynaecological opinion, in which case treating the condition should help rectify hair loss.' Other conditions can impact hair too, namely metabolic conditions such as diabetes, which can affect both men and women. 'As well as affecting the hair cycle directly, the disturbance in metabolism can also cause increased shedding (as a type of stress on the body), though it's not as common as, say PCOS. Generally speaking, correcting or treating the condition is the best way to help fix the problem.'
7. You're taking too many supplements
Around half of us take supplements regularly but many of us could be unknowingly overdosing, causing more harm than good. 'While vitamin A and selenium, for example, play an important role in hair health, taking too much vitamin A in particular can have the opposite effect, affecting hair and prompting sudden shedding,' says Dr Farjo. 'Most people eating a healthy, balanced diet in this part of the world shouldn't be lacking in vitamins and most likely don't need supplements.'
The only exception? Vitamin D. ' Vitamin D deficiency is associated with hair loss (specifically telogen effluvium, which occurs all over the head) and since most of us are deficient I'd recommend taking it.'
8. Your medication is to blame
Anything from blood thinners and antidepressants to the contraceptive pill could cause hair loss, with many of us completely in the dark. 'Over 100 types of medication have hair loss listed as a potential side effect, which is why it's so important to flag any medication to your doctor in the event of hair loss,' says Dr Farjo. 'When seeing new patients, I always take a thorough medical history to investigate whether the hair loss history coincides with beginning those specific medications, before looking at whether it could be changed to something that doesn't affect hair.'
Warfarin and heparin are two blood thinners (or 'anticoagulants') that could result in telogen effluvium (all-over hair shedding) and some antidepressants, namely selective serotonin reuptake inhibitors (SSRIs) like fluoxetine (Prozac) and sertraline have been linked to hair loss, too. Other medications that could prove harmful to hair include some beta-blockers, chemotherapy treatments and anticonvulsants (for seizures). While stopping medication can stop the hair loss, it's important to do so under medical supervision.
9. You're taking weight-loss drugs
As the likes of Wegovy and Mounjaro gain traction in the UK, it's likely we'll see some side-effects too, which could include hair loss, says Dr Farjo. 'Weight-loss drugs have already been linked to hair loss and there's a double whammy; firstly, hair loss could potentially be a direct effect of the way the drug chemically interacts with the body.
'But anything that causes sudden or severe weight loss (in other words, exerts stress on the body) can trigger telogen effluvium [all-over hair loss] despite it not presenting as a 'typical' stressful situation.' There's also the potential for nutritional deficiencies if someone's appetite is very low.
The solution, of course, is to stop taking it, under a doctor's supervision and, if needed, to seek a hair-friendly alternative.
10. You've just had a baby
The postpartum hair shed is a very real phenomenon – thanks to out-of-kilter hormones, once again.
'When pregnant, a woman produces more oestrogen, which means the percentage of hairs on their head in the 'growth phase' of the hair's cycle becomes higher than normal,' Dr Farjo explains. 'This means pregnant women stop shedding hair at the normal rate [we typically lose between 100-150 hairs per day] giving the impression hair is thicker.'
But what goes up, must come down and post-birth, a balancing act takes place, in conjunction with falling oestrogen levels. The result is usually thinning, all over the head. 'The body 'over sheds' to make up for the hairs that should have been lost while pregnant. Of course, with hair feeling thicker in pregnancy, that postpartum loss can feel even more dramatic, but after a few months that overcompensation stops and things settle.'
Perhaps frustratingly, waiting it out is the best port of call. 'Six months is a sensible timeframe to see improvement – medication isn't recommended when breastfeeding, for example. If a patient was especially anxious, they could try low-level light therapy, an at-home laser device which can stimulate hair growth. Crucially, it can help patients feel more positive and relaxed about the situation, since stress or anxiety around hair loss can make it even worse.'
11. You're on the Pill
Just as fluctuating hormone levels post-childbirth, or during perimenopause or menopause can affect hair, so can the contraceptive pill, which contains synthetic oestrogen and progesterone (progestin). Unlike natural progesterone, the synthetic version often has what's called 'androgenic activity' which can cause or worsen hair loss. 'Oestrogen is generally good for hair so if your contraceptive has sufficient oestrogen (versus a low-oestrogen or progestin-only contraceptive) it shouldn't contribute to hair loss,' says Dr Farjo.
While some contraceptive pills can make hair loss worse, according to Dr Farjo, the important thing is to figure out whether the hair loss is genuinely coinciding with starting on it, rather than assuming.
For those concerned, contraceptive pills Yasmin and Dianette, for example, contain anti-androgenic progestins and are often dubbed 'hair-friendly' options, but it's important to speak to your doctor about potential risks and side effects before taking. The good news is, in most cases any contraceptive-pill-related hair loss is entirely treatable – it's a straightforward case of swapping to something more suitable.
12. You have an STI
Specifically, syphilis. The infection, which occurs in three stages, can cause uneven, patchy hair loss (sometimes described as 'moth-eaten alopecia') both on the scalp and on eyebrows, eyelashes, beards and sometimes affecting body hair, too.
'Our standard medical history form for hair loss patients used to ask whether there's a history of syphilis, but we stopped asking because it became quite uncommon – I hear it's becoming less so recently,' notes Dr Farjo. 'In some cases, it can cause hair loss and further difficulty for patients considering, say, hair transplant surgery (there's a risk of spreading infection, as well as poor healing and scarring).' As with other conditions, once treatment has taken place, symptoms – including hair loss – should ease.
13. It's alopecia areata
Generally, alopecia areata is defined as patchy hair loss (either in a band or in oval patches across the head) but there are different types – some people experience 'diffuse' alopecia areata for example, which is all-over thinning instead of patches. It can affect men and women, but it's more common in children than adults.
Sometimes it's noticed alongside dented or pitted nails, too. Around one in every 4,000 people develop it in the UK each year and it's technically classed as an autoimmune disease (the immune system attacks the body's hair follicles, causing them to fall out).
'The best way of treating it is through prescription medications such as steroids and JAK inhibitors [drugs used to treat chronic inflammatory conditions],' says Dr Farjo. 'Having said this, for many people, alopecia areata resolves itself without treatment. For others in advanced cases, it can progress onto 'alopecia totalis' [complete loss of hair on the head] or 'alopecia universalis' [loss of hair all over the body].'