B12 deficiency and leg pain: what could be behind it

September 28, 2026approx. 16 minutesby mybody®x Editorial & Expert Team

In this article

Can leg pain be caused by a B12 deficiency?

A B12 deficiency can damage nerves and the spinal cord, the bundle of nerves in the spinal canal, and the legs are among the places where this can become noticeable (Briani et al., 2013; Healton et al., 1991). However, the British guideline lists tingling or numbness as typical signs, while a review describes pain as a symptom of nerve damage from any cause (NICE, 2024; Callaghan et al., 2015).

If you notice tingling in your toes or an unsteady gait and then come across the term B12, the first thing you want to know is whether the two could be related. The short answer is: they could be. The longer answer depends on where the symptoms started and what else might be causing them.

Nerve symptoms come first. In a case series from two New York clinics, evaluated over 17 years, they were the first signs of deficiency in most of the 153 episodes, especially abnormal sensations such as tingling or unsteadiness while walking (Healton et al., 1991).

A common objection is: But my blood test results were normal. That is not necessarily a contradiction, since nerve symptoms can occur before changes in the blood, according to a review (Briani et al., 2013). In the case series, hematocrit was normal in 27.4% of episodes, and the mean size of red blood cells, or MCV, was normal in 23.0% (Healton et al., 1991).

A UK guideline on B12 and folate therefore states that the clinical picture is most important when interpreting B12 laboratory results, because there is no gold standard—that is, no single test that can reliably establish a deficiency (Devalia et al., 2014). The clinical picture means the symptoms and the findings from the medical examination together.

The UK’s National Institute for Health and Care Excellence (NICE), which addresses its guideline to healthcare professionals, is even more explicit (NICE, 2024). It refers to megaloblastic anemia, a blood disorder involving enlarged red blood cells, and to the spinal cord form of the deficiency.

Subacute combined degeneration is the spinal cord form of the deficiency (Briani et al., 2013). In German, it is called funicular myelosis. For you, the recommendation does not mean taking anything yourself; it means that nerve symptoms should not be left waiting in the doctor’s office.

What does B12 deficiency feel like in the feet and legs?

Tingling or numbness in the hands and feet, as well as balance problems, are documented (MedlinePlus, 2026). In the clinical examination, reduced vibration and position sense in the legs was the most common finding in the case series (Healton et al., 1991).

Vibration sense is the skin’s ability to feel fine vibrations. Position sense is the ability to sense the body’s position and movement without looking (NICE, 2024). When it declines, balance can suffer: the UK guideline lists balance problems and falls because this sense is impaired, as well as an unsteady gait (NICE, 2024).

According to the guideline, the cause may be damage to nerves outside the brain and spinal cord, or a disease of the spinal cord itself (NICE, 2024). When several nerves are affected at once, medicine calls this polyneuropathy.

A medical encyclopedia from the U.S. National Library of Medicine states that a long-term low B12 level can damage the nerves (MedlinePlus, 2026). It also notes that a deficiency may cause no symptoms or only mild ones (MedlinePlus, 2026).

And what about the pain you may have been looking for? An overview of polyneuropathy describes pain, along with tingling and numbness, as possible symptoms of nerve damage from any cause (Callaghan et al., 2015). The British guideline lists tingling or numbness, not pain, as a typical sign of B12 deficiency (NICE, 2024).

The full list of possible signs, from fatigue to inflammation of the tongue, is covered in the overview of symptoms of vitamin B12 deficiency. Here, the focus is on the legs.

Why does B12 deficiency affect the legs?

Two pathways are supported by evidence: B12 deficiency can damage the nerves in the arms and legs, and it can affect the spinal cord (Briani et al., 2013). By contrast, the sources used in this guide do not explain why polyneuropathy starts in the toes.

The first pathway is through the nerves outside the spinal cord. According to an overview, one of the most common forms of polyneuropathy is length-dependent (Callaghan et al., 2015). Numbness or tingling typically starts in the toes and spreads slowly upward (Callaghan et al., 2015). According to this overview, the hands are affected only after the symptoms have reached at least the knee (Callaghan et al., 2015).

This distribution is called the stocking-glove pattern (Callaghan et al., 2015). The same overview lists B12 deficiency among the most common causes of this kind of polyneuropathy (Callaghan et al., 2015).

The second pathway is through the spinal cord, the bundle of nerves in the spinal canal. According to an overview, the spinal cord form of the deficiency presents with altered sensations on both sides and impaired sense of position (Briani et al., 2013). Spastic paralysis can also occur in the legs or in both the arms and legs; this is paralysis with increased muscle tone (Briani et al., 2013).

Damage limited to the nerves in the arms and legs is less common according to the same overview, but is probably overlooked (Briani et al., 2013). A medical examination is therefore needed to determine whether tingling and unsteadiness when walking come from the nerves or the spinal cord.

That leaves the question of why the toes are affected first. The overview describes the pattern but does not explain why it occurs (Callaghan et al., 2015). So the question remains open here, rather than being filled with a plausible-sounding explanation.

What besides a B12 deficiency could be behind leg symptoms?

B12 deficiency is just one of several possible causes: a review lists it alongside diabetes among the most common causes of polyneuropathy (Callaghan et al., 2015). According to the same review, nerve damage in the arms and legs affects 2 to 7% of the population (Callaghan et al., 2015).

The pattern alone doesn’t reveal what’s causing the symptoms. You need test results and a medical examination to find out.

Could diabetes be causing the tingling in your legs?

According to the review, diabetes is the most common cause of polyneuropathy, accounting for 32 to 53% of cases (Callaghan et al., 2015). It names alcohol as the second most common cause, usually after decades of daily consumption (Callaghan et al., 2015). The review also lists prediabetes among the common causes (Callaghan et al., 2015).

When the cause is unknown, the review recommends measuring B12 levels and blood sugar (Callaghan et al., 2015). So both belong on the list for your appointment.

Which risk factors point to B12 deficiency?

A review for primary care physicians notes that targeted testing for B12 deficiency may be appropriate for people with risk factors, but is not recommended for adults without particular risk factors (Langan and Goodbred, 2017). The review lists metformin, a medication used to treat high blood sugar, when taken for more than 4 months, and acid blockers for heartburn when taken for more than 12 months (Langan and Goodbred, 2017).

These include a vegan or strictly vegetarian diet and being over 75 years old (Langan and Goodbred, 2017). Stomach or small intestine surgery is also on the list, as are chronic inflammatory bowel diseases (Langan and Goodbred, 2017).

The article on vitamin deficiencies caused by medications explains how medications affect nutrient levels. The overview of the causes of vitamin B12 deficiency covers other reasons for low levels. If you take any of the medications mentioned, discuss any changes with your healthcare provider.

What if no cause is found for the polyneuropathy?

According to the review, no cause is found in 24 to 27% of polyneuropathies (Callaghan et al., 2015). A small case series recommends systematically ruling out B12 deficiency when nerve damage has no apparent cause, because the damage may be reversible (Franques et al., 2019).

In this series, serum B12, measured in the liquid part of the blood, was low in only 4 of 9 people (Franques et al., 2019). Only people whose symptoms improved with B12 were included, so this figure cannot be used to estimate how common it is (Franques et al., 2019). However, it shows that a single serum level may not settle the question.

What if B12 deficiency feels more like a joint problem?

Symptoms that feel like a joint problem are covered in a separate guide. The article on B12 deficiency and joint pain covers those symptoms, while this one focuses on nerve effects. An examination at a clinic can determine where the distinction lies for you.

What effects can B12 deficiency leave behind, and what do studies say about recovery?

B12 deficiency can affect the nerves and spinal cord and alter the blood count, but it does not have to (Briani et al., 2013). A case series provides data on recovery: nerve symptoms resolved completely after treatment in just under half of cases (Healton et al., 1991).

A blood count is a laboratory test of blood cells, which includes hematocrit and MCV. The table separates the levels; the figures from Healton et al. (1991) apply to all nerve symptoms combined.

Levels of B12 deficiency

Sources: Healton et al., 1991 · Briani et al., 2013 · NICE, 2024 · MedlinePlus, 2026

The median, that is, the middle value when all cases are arranged in order, was 4 months between the onset of symptoms and diagnosis in the case series (Healton et al., 1991). The longer this period, the more severe the nerve symptoms before treatment (Healton et al., 1991).

Which warning signs in the legs should be assessed by a doctor?

Nerve symptoms in the legs should be assessed by your primary care provider without undue delay, because nerve damage can persist if treatment does not begin soon after symptoms start, according to a medical reference work (MedlinePlus, 2026). A review specifically lists some signs as reasons for a neurological assessment (Callaghan et al., 2015).

The checklist below is for self-assessment, not diagnosis. It can help you prepare for your conversation: if any item applies, be sure to mention it at your appointment. Include any medications you take or pre-existing conditions you have in the conversation, too.

When to see your doctor

According to the review, these signs are reasons to consult a neurologist (Callaghan et al., 2015). They are not emergency criteria. Your primary care provider is the first point of contact and can help arrange a referral.

For suspected B12 deficiency, the UK guideline lists balance problems and falls as possible signs (NICE, 2024). An unsteady gait is therefore not something to leave until your next routine appointment.

What should you do about leg symptoms and suspected B12 deficiency?

The first step is to see your primary care provider. They can check your B12 level and examine your nerves; only both together provide a full picture. An at-home blood test can show your B12 level at a single point in time, but it cannot replace a nerve examination.

Before your appointment, note when the symptoms started and where they began. Also write down which medications you take, especially if you take metformin or an acid blocker (Langan and Goodbred, 2017). Note whether both sides are affected, too.

If the lab result does not match clear signs of deficiency, treatment should not be delayed, according to the UK guideline, to prevent nerve damage (Devalia et al., 2014). The doctor's office decides how to treat it.

The 1991 case series provides the clearest figures on recovery, and all those affected responded to treatment (Healton et al., 1991). Nerve symptoms completely resolved in just under half, and their severity decreased by at least half in 91% (Healton et al., 1991). These are findings from a case series, not a guarantee for an individual.

For symptoms in general, the UK guideline notes that improvement may occur within 2 weeks of starting treatment, but it can take up to 3 months (NICE, 2024). A small case series also shows that nerve symptoms can improve within the first few weeks (Franques et al., 2019). The guide Treating B12 deficiency: how long it takes explains how long improvement may take depending on the symptom.

You can also collect your own data point. The VitalCheck by mybody®x (MYBODY Lab GmbH) is an at-home blood test that provides a snapshot of B12 and folate levels. You collect the sample yourself, and it is analyzed at a specialized laboratory in Germany.

So the test is no substitute for talking to a doctor, but it can help you prepare for one.

Limitations: What a B12 blood test cannot show about leg symptoms

A blood test is a snapshot, not a diagnosis. An abnormal result does not automatically mean you have a condition; it’s a reason to take a closer look with your doctor.

A blood test cannot determine whether there is nerve damage; an examination at your doctor’s office can show whether the nerves or spinal cord are affected. The VitalCheck does not measure methylmalonic acid and homocysteine, two metabolic markers that UK guidelines list as additional tests (NICE, 2024; Devalia et al., 2014).

A blood count is not part of the test either, so it does not detect anemia. Your doctor’s office checks for that with a blood count.

The figures on recovery come from a retrospective case series at two clinics with no control group (Healton et al., 1991). The overview of causes and warning signs covers polyneuropathies in general, not specifically B12 deficiency (Callaghan et al., 2015).

Why is it worth getting leg symptoms checked early if you suspect B12 deficiency?

Time matters: In the case series, nerve symptoms improved less the longer they had been present before diagnosis (Healton et al., 1991). An initial response was always seen within the first 3 months of treatment (Healton et al., 1991).

If treatment begins, the UK guideline recommends a first follow-up appointment after 3 months, when improvement and new symptoms should be discussed (NICE, 2024). Symptoms may even get worse at first, but should then improve (NICE, 2024). If they get worse or new ones appear, the guideline says to seek medical help without waiting for the next appointment (NICE, 2024).

Tingling in your toes does not prove you have a B12 deficiency. It’s a good reason to get it checked, and soon.

Frequently asked questions

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Sources

1. Healton et al.: Neurological symptoms in cobalamin deficiency, Medicine (1991) - europepmc.org
2. Callaghan et al.: Distal symmetric polyneuropathy, review, JAMA (2015) - europepmc.org
3. National Institute for Health and Care Excellence: Vitamin B12 deficiency in over 16s, NG239 (2024) - nice.org.uk
4. Briani et al.: Cobalamin deficiency, clinical presentation, Nutrients (2013) - europepmc.org

Nerve symptoms, blood counts, and recovery from the case series are based on [1], polyneuropathy and warning signs on [2]. Symptoms and timeline come from [3], and the spinal cord form from [4]. Additional sources: Franques et al. (2019) on the case series with serum B12 levels, and Langan and Goodbred (2017) on risk factors. Also Devalia et al. (British Society for Haematology, 2014) on interpreting lab results, and MedlinePlus (2026) on nerve symptoms. VitalCheck price and process: as of 28.09.2026; subject to change. All sources checked on 28.09.2026.