12 Common Vitamin B12 Deficiency Symptoms
Vitamin B12 deficiency affects about 6% of people under the age of 60 and nearly one in five people over the age of 60. There is no definitive test for vitamin B12 deficiency, and the symptoms can be non-specific.1 This makes diagnosing vitamin B12 deficiency somewhat challenging. Screening for vitamin B12 deficiency is typically not recommended unless you are at increased risk.2 Assess your risk after reviewing these common vitamin B12 deficiency symptoms.
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Red blood cells carry oxygen to your body cells. Vitamin B12 is essential to produce healthy red blood cells. A vitamin B12 deficiency can decrease red blood cell function and production (megaloblastic anemia), which can impair oxygen delivery to your cells. Without optimal oxygen levels, your body cells do not function as well, resulting in fatigue.3
2. Pale skin color
Pallor is an unnaturally pale skin color. The linings of the eyes, lips, and nail beds may also appear pale. Anemia due to a lack of vitamin B12 can cause pale skin color. This can be due to decreased blood density due to anemia.4
When red blood cells are not functioning well due to abnormalities in size or shape, they may be broken down more quickly, causing increased bilirubin. An increase in bilirubin in the body can cause the skin and whites of the eyes to look yellow, a condition called jaundice.4
4. Shortness of breath
Shortness of breath or breathlessness is due to anemia from a lack of vitamin B12. When your body cannot produce enough red blood cells to carry oxygen to the body tissues, your heart pumps faster in response to a decrease in red blood cells. Blood passes through the lungs more quickly, making it difficult to fully oxygenate the red blood cells, resulting in shortness of breath.
Lightheadedness is a subjective symptom that has many potential causes. One reason people may feel lightheaded is anemia. Another common cause of lightheadedness is postural hypotension. This occurs when a person’s blood pressure does not respond quickly enough when moving from sitting or lying to standing.
6. Numbness and tingling sensations
Vitamin B12 deficiency can cause neurologic abnormalities, including numbness and tingling. Myelin is a fatty covering over the surface of nerves. It speeds up nerve conduction. When myelin becomes thinned or damaged, it can cause neurologic symptoms.
7. Coordination challenges or gait abnormalities
Vitamin B12 is essential to maintain myelin, a fatty covering over nerve cells. Myelin is an insulator that is essential for effective electrical impulse transmission through nerve cells. When myelin breaks down and transmission slows, people may experience difficulty with coordination, balance, and movement.5
8. Difficulty concentrating
Megaloblastic anemia from folate and vitamin B12 deficiency can cause numerous cognitive changes, including difficulty thinking and concentrating.
Megaloblastic anemia can cause a constellation of symptoms, including depression, mania, irritability, paranoia, and emotional lability.5
10. Mouth soreness
Many people with vitamin B12 deficiency report pain in their mouth and a painful tongue. The tongue has a shiny appearance (glossitis).
11. Muscle cramps
Damage to myelin on nerve cells and decreased oxygen levels in muscle tissue can cause muscle cramping and soreness.
12. Erectile dysfunction
Erectile dysfunction, or the inability to get and maintain an erection, can occur due to decreased blood flow to the penis or a change in nerve transmission. Vitamin B12 deficiency can cause anemia, which results in decreased oxygenation of body tissues, and demyelination or damage to the fatty coverings over nerves. Both of these can contribute to erectile dysfunction.
Not everyone who has vitamin B12 deficiency has these symptoms. Only about one in five people with vitamin B12 deficiency have megaloblastic anemia. Researchers have also found a poor correlation between vitamin B12 levels and symptoms associated with vitamin B12 deficiency.6
Frequently Asked Questions
What happens when you’re low on vitamin B12?
Vitamin B12 has several important roles in the body, including:1
Helping to produce energy by converting food into glucose
Maintaining healthy nerve function
Making DNA, the genetic material in all cells
Helping to form red blood cells
Helping enzymes to function as a cofactor
Controlling homocysteine levels
Vitamin B12 deficiency can cause several health problems, including anemia, nerve damage and dysfunction, and neurologic symptoms such as memory loss, difficulty concentrating, and mood disorders.
What is the most common cause of B12 deficiency?
Cyanocobalamin, or vitamin B12, is found in various foods, including fish, shellfish, meats, nutritional yeast, fortified cereals, and dairy products. The U.S. Department of Health and the Institute of Medicine recommend that all adults who are not pregnant or lactating take 2.6 micrograms of vitamin B12 daily. In the United States, the average intake is 3.4 mcg per day. While healthy people who consume an omnivore diet rarely have a vitamin B12 deficiency, factors that put people at risk for vitamin B12 deficiency include the following:6
Being over age 75
Consuming a vegan or vegetarian diet
Consuming excess alcohol
Having an autoimmune condition or inflammatory disease that affects the stomach
Having decreased stomach acid
Having stomach surgery
Taking antacids frequently
Taking high doses of folic acid
Taking metformin for more than four months
What is the fastest way to fix B12 deficiency?
The fastest way to fix vitamin B12 deficiency is to supplement with vitamin B12 injections. The most common cause of vitamin B12 deficiency is an inability to absorb the vitamin through the gut. Injecting vitamin B12 bypasses the stomach and delivers vitamin B12 directly to the organs and tissues that need it
Learn more about buying Vitamin B12 injections online
While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.
1. Hunt A, Harrington D, Robinson S. Vitamin B<sub>12</sub> deficiency. BMJ : British Medical Journal. 2014;349:g5226. doi:10.1136/bmj.g5226
2. Langan RC, Goodbred AJ. Vitamin B12 Deficiency: Recognition and Management. Am Fam Physician. Sep 15 2017;96(6):384-389.
3. Tardy AL, Pouteau E, Marquez D, Yilmaz C, Scholey A. Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients. 2020 Jan 16;12(1):228. doi: 10.3390/nu12010228. PMID: 31963141; PMCID: PMC7019700.
4. Ankar A, Kumar A. Vitamin B12 Deficiency. [Updated 2022 Oct 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441923/
5. Stabler, S.P., 2013. Vitamin B12Deficiency. New England Journal of Medicine 368, 149–160.. https://doi.org/10.1056/nejmcp1113996
6. Wolffenbuttel BHR, Wouters HJCM, Heiner-Fokkema MR, van der Klauw MM. The Many Faces of Cobalamin (Vitamin B12) Deficiency. Mayo Clin Proc Innov Qual Outcomes. 2019 May 27;3(2):200-214. doi: 10.1016/j.mayocpiqo.2019.03.002. PMID: 31193945; PMCID: PMC6543499.