Understanding the Symptoms of Low B12 and Folate

November 18, 2025 •

2 min read

According to the National Institutes of Health, B12 insufficiency affects approximately 12.5% of adults over 19. Knowing the common symptoms of low B12 and folate is crucial because deficiencies in these essential vitamins can lead to a wide range of health problems, which often develop slowly and can be easily mistaken for other conditions.

Quick Summary

This guide details the physical, neurological, and psychological symptoms associated with low B12 and folate levels, highlights the key differences between the two deficiencies, and explains the importance of early diagnosis and treatment.

Key Points

Shared Anemia Symptoms: Both low B12 and folate can cause fatigue, weakness, pale skin, shortness of breath, and a sore or red tongue, as these are all signs of megaloblastic anemia.
B12 Affects the Nervous System: A key differentiator is that B12 deficiency can lead to specific neurological issues like pins and needles, balance problems, and cognitive decline, which can become permanent if left untreated.
Folate is Critical in Pregnancy: Folate deficiency poses a significant risk of neural tube defects and other birth abnormalities for pregnant women and their babies.
Correct Diagnosis is Vital: It is dangerous to treat an undiagnosed B12 deficiency with only folic acid, as it can hide the anemia while neurological damage worsens. Proper blood testing is necessary to distinguish between the two.
Causes Vary: Common causes include poor diet (especially vegan for B12), malabsorption disorders like Crohn's and celiac disease, pernicious anemia (for B12), and certain medications.
Treatment is Effective: With proper diagnosis, both deficiencies are treatable—often with injections or high-dose oral supplements for B12 and folic acid tablets for folate deficiency.

What Are the Shared Symptoms of Low B12 and Folate?

Both vitamin B12 and folate are essential for creating healthy red blood cells and DNA. A lack of either can cause megaloblastic anemia, leading to shared symptoms as the body struggles with oxygen transport.

Common symptoms of megaloblastic anemia include:

Fatigue and weakness.
Pale or yellowish skin.
Shortness of breath and heart palpitations.
A sore, red tongue, possibly with mouth ulcers.
Cognitive issues like poor memory or concentration.
Headaches.
Digestive problems such as diarrhea, nausea, or loss of appetite.

What are the Unique Symptoms for Low B12?

Low B12 can cause unique neurological damage if not treated because of its role in nerve health.

Unique neurological and psychological symptoms of B12 deficiency can include:

Tingling or 'pins and needles,' especially in the hands and feet.
Difficulty with balance and coordination.
Psychological issues like depression, anxiety, or more severe problems.
Vision problems, including blurred or double vision.
Increased muscle weakness.

What are the Unique Symptoms for Low Folate?

Isolated folate deficiency typically doesn't cause the severe nerve damage seen with low B12. However, it's particularly important during pregnancy.

Unique considerations for folate deficiency include:

Increased risk of neural tube defects like spina bifida in developing babies.
Higher risk of premature birth or low birth weight.

Low B12 vs. Low Folate: A Comparison


Feature	Low B12 (Cobalamin)	Low Folate (B9)
Symptom Onset	Gradual, due to body's large storage.	Relatively rapid, due to smaller storage.
Neurological Symptoms	Common, can be irreversible if untreated.	Typically absent in isolated deficiency.
Diagnosis	Elevated homocysteine and methylmalonic acid (MMA).	Elevated homocysteine, normal MMA.
Common Causes	Pernicious anemia, vegan diet, poor absorption, certain medications.	Poor diet, alcohol misuse, malabsorption conditions, pregnancy, certain medications.
Treatment	Often starts with injections, then regular injections or high-dose oral tablets.	Oral folic acid tablets.

Conclusion

Low B12 and folate share symptoms like fatigue and cognitive issues due to megaloblastic anemia. A key difference is the potential for irreversible nerve damage with B12 deficiency. Accurate diagnosis through blood tests is crucial because treating B12 deficiency with only folate can mask anemia while nerve damage worsens. Consult a healthcare professional if you have persistent symptoms for proper diagnosis and treatment.

Why is early diagnosis so important for low B12 and folate?

Early diagnosis is critical because while many symptoms are shared, the long-term consequences differ significantly. Untreated B12 deficiency can lead to irreversible neurological damage, including memory loss and coordination issues. For folate, early diagnosis is vital for women who are pregnant or planning to be, as it can help prevent serious birth defects. Accurate diagnosis is achieved through specific blood tests, which allow healthcare providers to distinguish between the two conditions and prescribe the correct course of action, which could involve dietary changes, oral supplements, or injections. Timely intervention can often reverse symptoms and prevent long-term complications.

Frequently Asked Questions

Yes, fatigue is one of the most common symptoms of both low B12 and folate. Both are essential for red blood cell production, and a deficiency can lead to megaloblastic anemia, resulting in extreme tiredness and a lack of energy.

The fastest treatment depends on the cause. For B12 deficiency, injections are often used initially to quickly restore levels, followed by regular injections or high-dose oral tablets. Folate deficiency is typically treated with daily oral folic acid tablets.

Doctors use specific blood tests to differentiate. Both deficiencies cause elevated homocysteine levels, but only B12 deficiency also causes elevated methylmalonic acid (MMA). This difference helps pinpoint the correct vitamin deficiency.

Taking folic acid can mask the anemia caused by a B12 deficiency, making you feel better temporarily. However, it will not prevent or treat the underlying B12-related neurological damage, which can progress and become irreversible.

Yes, a deficiency in vitamin B12 can cause neurological problems and damage to the nervous system. This can lead to symptoms like pins and needles in the hands and feet, numbness, balance issues, and cognitive impairment.

Yes, people on a strict vegan diet are at higher risk for B12 deficiency because B12 is found almost exclusively in animal products. It is recommended that vegans use fortified foods and B12 supplements to maintain healthy levels.

Pregnancy significantly increases the body's need for folate to support the rapid growth and development of the fetus. Inadequate folate during this period increases the risk of birth defects, particularly neural tube defects.