B12 Deficiency Symptoms: The Full Checklist and Who Is at Risk
Tingling feet get the attention, but low B12 can also show up as tiredness, a sore red tongue or a fog that will not lift. The NHS lists a wider range than most people expect, from mouth ulcers to memory changes, and this guide puts them in one place.
At a glance
- Energy: extreme tiredness and a lack of energy.
- Mouth and tongue: a sore, red tongue and mouth ulcers.
- Nerves and eyes: pins and needles, muscle weakness and problems with vision.
- Mood and memory: anything from mild depression or anxiety to confusion, plus problems with memory, understanding and judgement.
- Rule of thumb: a normal blood count does not rule out low B12, and some nerve problems can be permanent.
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What are the early B12 deficiency symptoms?
The NHS lists these signs for vitamin B12 or folate deficiency. Extreme tiredness and a lack of energy are easy to blame on a busy year. Its list also covers the mouth and tongue, with a sore and red tongue and mouth ulcers. Nerve signs such as pins and needles and muscle weakness sit alongside vision problems and changes in mood and thinking. The NHS does not put them in order, so treat them as a set to check against, not a timeline.
Who is most at risk of low B12?
A symptom list is only half the picture. Risk comes from what you eat, what you take and how your body absorbs what you eat. The NHS names the groups below, and the table is a checklist, not a diagnosis.
| Who | Why the NHS flags them |
|---|---|
| People on a vegan diet | Those who do not take B12 products |
| Older people | Both B12 and folate deficiency are more common with age |
| People on some medicines | Anti-seizure medicines and proton pump inhibitors are named |
| People with pernicious anaemia | The immune system attacks healthy cells in the stomach |
| People with a long, restrictive or poor diet | The NHS names this as a risk factor |
Does metformin count as a risk?
It can be part of the picture. The NHS metformin page lists vitamin B12 deficiency among the side effects of the medicine. That does not mean you should stop metformin, and it does not mean you have a deficiency. It means the question belongs on your list when you talk to the prescriber about a B12 check.
Why does a normal blood count not settle it?
Many people assume that a clear blood count means B12 is fine. The NHS says some of these problems can also happen when there is a deficiency but no anaemia. That makes the nerve and mood signs as important as the blood result, and a normal count is not the end of the question.
Nerve signs need the most attention. The NHS notes that problems with the nervous system can sometimes be permanent, which is why early diagnosis matters. Do not wait for a blood count to change before you raise numbness, weakness, vision changes or memory problems.
What should I do if the symptoms match?
- Write the symptoms down with dates. Include the tiredness, the tongue, the mouth ulcers, the pins and needles, any vision changes and any memory or mood changes.
- List your medicines. Put metformin, anti-seizure medicines and acid-reducing medicines on the list, along with any herbal remedy you take. Our always-tired checklist covers the wider picture of tiredness.
- Describe your diet honestly. Say whether you eat any animal foods, and whether you take any B12 products.
- Ask for the test your doctor thinks fits. A borderline result needs a plan, and our guide to the B12 test report explains the grey zone.
- Ask before starting any B12 product. The right route and the right check depend on the test and your history, so let the clinician set it.
Try this: the tongue and feet note
Look at your tongue in daylight once a week and write down what you see. Note any tingling in your feet and when it happens. Bring that note to the appointment. A clear note gives the clinician far more to work with than a sentence like “I just feel off.”
See a GP if you think you may have a B12 or folate deficiency, for example if numbness, weakness, vision changes or memory problems are new or keep coming back. New or severe mood changes also need a GP appointment. If you ever have thoughts of harming yourself, contact emergency services or a crisis line straight away.
The NHS lists pregnancy complications as a possible result of prolonged deficiency. If you are pregnant or planning a pregnancy, raise B12 with your midwife or doctor, who can check your needs.
Your B12 symptom questions, answered
What are the first signs of B12 deficiency?
The NHS lists extreme tiredness and a lack of energy among the signs of B12 or folate deficiency, along with a sore, red tongue and mouth ulcers. The list does not put them in order, so look at them together.
Can low B12 cause memory problems?
Yes. The NHS lists problems with memory, understanding and judgement among the symptoms of B12 or folate deficiency, so new memory changes deserve a check.
Can low B12 cause low mood?
It can. The NHS lists psychological problems, from mild depression or anxiety to confusion, so a new mood change is worth raising with a doctor rather than explaining away.
Can B12 deficiency happen without anaemia?
Yes. The NHS says some of these problems can happen with a deficiency of B12 or folate even when there is no anaemia, so a normal blood count does not close the question.
Is B12 deficiency common in vegans?
The NHS names people who follow a vegan diet and do not take B12 products as being at risk. A vegan diet is a reason to ask for a check, not a diagnosis.
Does metformin cause B12 deficiency?
The NHS metformin page lists vitamin B12 deficiency as a side effect, so ask your prescriber whether a check fits you. Do not stop metformin on your own.
Do acid-reducing medicines affect B12?
The NHS names proton pump inhibitors as one of the medicine groups linked with a risk of B12 deficiency. If you take one and have symptoms, talk to the prescriber about a check.
Can nerve damage from low B12 be reversed?
Some nerve problems can be permanent, according to the NHS, which is why early testing matters. Do not wait for a blood count to change before you raise the symptoms.
Is tingling in the feet always a B12 problem?
No. Numbness and tingling have several causes, and our numbness causes guide covers the others. Pins and needles appear on the NHS list for B12 or folate deficiency, so the pattern and the blood tests decide it.
When should I see a doctor about these symptoms?
See a GP if you think you may have a B12 or folate deficiency, for example if numbness, weakness, vision changes or memory problems are new or keep coming back. The NHS says these conditions should be diagnosed and treated as soon as possible.
Do I need a blood count to check B12?
A blood count can be normal even when B12 is low, so ask your doctor which test they plan to order and what a borderline result would lead to.
Is treatment for low B12 a decision for the doctor?
Yes. Whether treatment is needed, and in what form, is the clinician’s decision after testing. Do not start a B12 product because a symptom checklist says so.
For tingling and burning feet specifically, read our burning feet and B12 guide. For the test side, the Vitamins and Minerals section covers how to read the results.