Noticing more hair on your pillow or falling out in the shower can be worrying, especially when the cause isn’t obvious. It’s common to start looking for possible explanations, and vitamin deficiencies like B12 are often one of the first things you may have come across.
Low B12 levels can contribute to hair loss in some people (1). However, the relationship isn’t straightforward, evidence is mixed, and B12 is rarely the only cause for thinning hair.
In this article:
What is vitamin B12 and what does it do?
How might B12 deficiency affect hair?
What does the evidence actually say?
What types of hair loss might B12 deficiency be linked to?
Who is most at risk of B12 deficiency?
What are the symptoms of vitamin B12 deficiency?
What should you do if you’re concerned?
Still worried about ongoing hair thinning?
FAQs
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What is vitamin B12 and what does it do?
Vitamin B12 (also called cobalamin) is a water-soluble vitamin that plays an essential role in:
DNA synthesis
Red blood cell production
Nerve function
Healthy cell turnover throughout the body
Hair follicles are among the fastest-dividing cells in the body, which means they depend on a steady supply of nutrients like B12 to function normally (1).
Unlike some vitamins, the body cannot make B12 itself. It must come from food sources such as meat, fish, eggs, and dairy products, or from supplements if your dietary intake is low. Because of this, people who avoid animal products are more likely to develop deficiency (3).
How might B12 deficiency affect hair?
Low B12 levels may affect hair growth indirectly rather than directly damaging hair follicles.
One reason is its role in red blood cell production. When B12 levels drop, the body can produce abnormally large red blood cells and develop anaemia, which reduces oxygen delivery to tissues including the scalp (2). Hair follicles are particularly sensitive to these changes.
Over time, this may shift more hairs into the resting phase of the growth cycle, leading to increased shedding. This pattern is typical of telogen effluvium, which causes thinning across the scalp rather than a receding hairline or patchy loss (4).
What does the evidence actually say?
Vitamin B12 levels are often checked in people with unexplained hair shedding, particularly when a specific type of hair loss called telogen effluvium is suspected (4,5). However, research looking at the link between B12 deficiency and hair loss has produced mixed results.
Some studies have found that people with shedding are slightly more likely to have low B12 levels than those without hair loss. But overall, average B12 levels tend to be similar between people with telogen effluvium and healthy control groups (1,5,6).
This suggests there is a link, but deficiency explains only a small proportion of cases. Current clinical guidance therefore suggests:
The evidence is associative rather than causal
Supplementation is not recommended unless deficiency is confirmed
The link appears strongest with specific types of shedding, not with all types of hair loss
Most hair loss has multiple contributing factors
In other words, correcting low B12 levels may help slow shedding if deficiency is present, but it’s unlikely to be the sole explanation in most cases.
Some reports also suggest that low B12 may play a role in premature greying, but this is uncommon and not fully understood (1).
What types of hair loss might B12 deficiency be linked to?
Vitamin B12 deficiency is most commonly associated with diffuse shedding across the scalp rather than patterned thinning (1). This includes telogen effluvium, which often develops after physical or mental stress or nutritional deficiencies (4).
If you have this type of hair loss, you may notice:
Increased hair shedding when brushing or washing your hair
Thinning across the whole scalp, rather than specific areas
A wider, more noticeable parting
Reduced overall hair volume and thickness
By contrast, B12 deficiency is unlikely to cause androgenetic alopecia (female or male pattern baldness), which is driven mainly by genetics and sensitivity to DHT (7). If your shedding follows a receding hairline pattern or thinning at the crown, clinically-proven medicines like finasteride (for men) and minoxidil are generally better hair loss treatments (7).
Who is most at risk of B12 deficiency?
Some people are more likely to develop low B12 levels than others. Higher-risk groups include (3):
Vegans and vegetarians
Older adults
People with absorption problems
Those taking long-term metformin
People with pernicious anaemia
Pernicious anaemia is an autoimmune condition that prevents the body from absorbing B12 from food properly (8). In these cases, treatment often involves injections, though oral supplementation may be suitable in some cases.
If you fall into one of these higher-risk groups, low B12 is more likely to be a contributing factor to hair shedding than in the general population. However, hair loss and other symptoms don’t always appear straight away.
What are the symptoms of vitamin B12 deficiency?
Hair shedding isn’t usually the first sign of low vitamin B12. Everyone shows different signs, but more common symptoms include (3,9):
Persistent tiredness or low energy
Pale or slightly yellow-tinged skin
Shortness of breath
Tingling or “pins and needles” in the hands and feet
Memory problems or difficulty concentrating
A sore or inflamed tongue
However, some people develop low B12 levels gradually without obvious symptoms, particularly if they follow a vegetarian or vegan diet or have absorption problems.
Taking a blood test is the only reliable way to confirm whether or not you have a deficiency. If you’re experiencing several of these symptoms alongside increased hair shedding, it’s worth asking your GP about testing to confirm.
What should you do if you’re concerned?
If you think low B12 levels could be causing you to lose hair, ask your GP for a blood test.
Hair loss rarely has a single nutritional cause, and vitamin B12 is just one of several nutrients that support normal hair growth. Deficiencies in iron, vitamin D, and zinc can all contribute to hair thinning (1). Like B12, these deficiencies are usually only relevant when confirmed through testing.
This is why testing with your GP is more helpful than starting supplements on your own. Taking unnecessary supplements is unlikely to help hair regrowth and may delay finding the real cause.
If deficiency is confirmed, treatment with B12 supplements may:
Reduce ongoing shedding
Support healthier regrowth with time
Improve other related symptoms such as fatigue or tingling sensations
However, hair recovery can take several months, and regrowth isn’t guaranteed if other factors are involved. Many people find their hair loss has more than one contributing cause, including stress, illness, hormonal changes, or genetic thinning. Directly targeting the cause is the best way to treat hair loss and see real improvements.
Oxford Online Pharmacy offers discreet online hair loss consultations to help identify suitable treatment options based on your symptoms.
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FAQs
Can taking B12 supplements stop hair loss?
Only if a confirmed deficiency is the contributing cause. Taking B12 supplements when your levels are already normal is unlikely to improve hair growth or slow shedding. This is why a blood test with your GP is recommended before starting supplements, rather than trying them on the assumption that low B12 is the cause.
How long does it take for hair to grow back after correcting a B12 deficiency?
Hair recovery after correcting a nutritional deficiency can take several months. Hair growth is a slow process, and regrowth is not guaranteed if other factors are also contributing to the shedding. Most people notice a reduction in shedding before they see visible regrowth, this can be improved with other treatments like minoxidil or finasteride for men.
Can I test my B12 levels at home?
Home finger-prick B12 tests are available from some pharmacies and online providers, but a blood test arranged through your GP is more reliable and gives a fuller picture of your overall nutritional status. Your GP can also test for other deficiencies that are commonly linked to hair shedding at the same time, such as iron, vitamin D, and zinc.
Is hair loss from B12 deficiency permanent?
In most cases, no. Hair loss linked to a nutritional deficiency such as low B12 tends to be temporary. Once the deficiency is identified and treated, shedding usually slows and hair can begin to recover over time. However, if other causes such as genetic thinning or hormonal changes are also present, some degree of ongoing hair loss may continue regardless of B12 levels.
References
Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A. The Role of Vitamins and Minerals in Hair Loss: A Review. Dermatology and therapy [Internet]. 2019;9(1):51–70.
NHS. Vitamin B12 or folate deficiency anaemia [Internet]. NHS. NHS; 2023.
NICE. Recommendations | Vitamin B12 deficiency in over 16s: diagnosis and management | Guidance | NICE [Internet]. www.nice.org.uk. 2024.
British Association of Dermatologists. Telogen effluvium [Internet]. Bad.org.uk. 2020.
Durusu Turkoglu IN, Turkoglu AK, Soylu S, Gencer G, Duman R. A comprehensive investigation of biochemical status in patients with telogen effluvium: Analysis of Hb, ferritin, vitamin B12, vitamin D, thyroid function tests, zinc, copper, biotin, and selenium levels. Journal of Cosmetic Dermatology. 2024 Aug 6;23(12):4277–84.
Ömer Karakoyun, Erhan Ayhan, İsmail Yıldız. Retrospective Review of 2851 Female Patients With Telogen Effluvium: A Single‐Center Experience. Journal of Cosmetic Dermatology. 2025 Feb 1;24(2).
British Association of Dermatologists. Hair loss male pattern (androgenetic alopecia) [Internet]. Bad.org.uk. 2024.
Vaqar S, Shackelford K. Pernicious anemia [Internet]. Nih.gov. StatPearls Publishing; 2023.
NHS. Symptoms - vitamin B12 or folate deficiency anaemia [Internet]. NHS. 2019.