B vitamin shortfalls rarely announce themselves clearly. The signs overlap with a dozen other things, from poor sleep to iron deficiency. Here's what low B status can look like, vitamin by vitamin, and when it's worth getting checked.
Written by Vita Globe Editorial Team | Reviewed against NIH Office of Dietary Supplements fact sheets
What are the signs you're low on B vitamins?
Common signs include fatigue and weakness, cracks at the corners of the mouth, a sore or swollen tongue, skin rashes, numbness or tingling in the hands and feet, and changes in mood or concentration[2][5][6]. Low B12 and folate can both cause a type of anemia with large red blood cells[5][6].
Caveat: These signs are nonspecific; many other conditions cause them. Only a blood test and a clinician can confirm a deficiency.
Sources: NIH ODS B12 · NIH ODS Folate · NIH ODS Riboflavin · Verified 2026-09-27
In this article
Why are low B vitamin signs so easy to miss?
The eight B vitamins share a lot of jobs, especially in energy metabolism and the nervous system, so running low on one can look a lot like running low on another. Early signs are also vague: tiredness, irritability, trouble concentrating. That's why B vitamin shortfalls often go unnoticed until they're more advanced.
Another complication: B12 deficiency can take years to develop because the body stores it, and high folic acid intake can mask its anemia while nerve damage progresses[6]. That's one reason self-diagnosing with a supplement isn't a great idea.
Which signs point to which B vitamin?
Here's a summary of signs that NIH fact sheets link to low intake or deficiency of each vitamin:
| Vitamin | Possible signs of deficiency |
|---|---|
| Thiamin (B1) | Weight loss, poor appetite, confusion, short-term memory problems, muscle weakness[1] |
| Riboflavin (B2) | Skin disorders, cracks and sores at the corners of the mouth, swollen mouth and throat, hair loss[2] |
| Niacin (B3) | In severe cases (pellagra): a pigmented rash on sun-exposed skin, digestive problems, depression and memory loss[3] |
| Vitamin B6 | Dermatitis with cracked lips and a sore tongue, depression and confusion, weakened immune function, anemia[4] |
| Folate (B9) | Large-cell (megaloblastic) anemia, weakness, fatigue, trouble concentrating, irritability, mouth sores[5] |
| Vitamin B12 | Megaloblastic anemia, fatigue, weakness, numbness and tingling in hands and feet, sore tongue; links to depression in some studies[6] |
| Biotin (B7) | Thinning hair, a scaly red rash around the eyes, nose and mouth, brittle nails (rare)[7] |
Pantothenic acid (B5) deficiency is extremely rare and seen mostly with severe malnutrition. For a closer look at the most common one, read Vitamin B12 deficiency: signs, causes and what actually helps.
Who is most likely to run low?
True deficiency is uncommon in healthy people eating a varied diet, but some groups are at higher risk:
- Adults over 50: lower stomach acid can reduce B12 absorption from food, and a notable share of older adults show signs of low thiamin status[6][1].
- Vegans and vegetarians: B12 occurs naturally only in animal foods[6].
- People who drink heavily: alcohol dependence is strongly linked to low thiamin, and also raises the risk of low B6[1][4].
- People on certain medications: metformin and acid-reducing drugs can lower B12; some antiepileptic drugs affect B6[6][4].
- People with gut or kidney conditions, or after weight-loss surgery: absorption and losses change[1][4][6].
- Pregnant people: recommended intakes rise for folate, B6 and other B vitamins[5][4].
When should you get tested instead of guessing?
See your healthcare provider, and ask about blood work, if you have:
- Numbness, tingling or balance problems, especially in the hands and feet[6]
- Fatigue that doesn't improve with better sleep
- Persistent mouth sores, a sore tongue or cracks at the corners of the mouth[2]
- Any of the risk factors above, especially long-term metformin use
Nerve-related symptoms from B12 deficiency deserve prompt attention, because damage can become permanent if it goes untreated[6]. A supplement is not a substitute for diagnosis.
How can you keep B vitamin levels healthy day to day?
Food comes first. Whole and fortified grains, eggs, dairy, meat, poultry, fish, legumes and leafy greens together cover most of the B family. If your diet has gaps, or you fall into a higher-risk group, a B complex can be a convenient way to top up. We cover what that looks like in what happens when you take vitamin B complex every day, and you can see what each vitamin does in the 8 B vitamins and what each one does.
The honest summary
- Fatigue, mouth and tongue changes, rashes and tingling can all signal low B vitamins, but they're nonspecific.
- B12 and folate shortfalls can both cause anemia; B12 can also affect the nerves[5][6].
- Older adults, vegans, heavy drinkers and people on certain medications are most at risk.
- Get tested before assuming. Treat a supplement as support, not a diagnosis.
Our option
Vita Globe Vitamin B Complex Gummies
For everyday top-up (not for treating a diagnosed deficiency), one gummy a day provides six B vitamins, including niacin, B6, folate and B12, plus vitamin C and inositol. It's vegan and gluten-free and tested by an independent third-party lab.
Frequently asked questions
How do I know if I need a B complex?
You can't know for sure from symptoms alone. If you're in a higher-risk group or have ongoing symptoms, ask your provider about blood tests. If you just want everyday nutritional support, a B complex at label directions is a common choice.
What does low vitamin B feel like?
Often tiredness, weakness, irritability or brain fog. More specific signs include cracks at the corners of the mouth, a sore tongue, and tingling in the hands and feet[2][6].
Can low B vitamins cause anxiety or low mood?
Low B6 and B12 have been linked to depression and confusion in NIH fact sheets[4][6], but mood symptoms have many causes. Talk to a clinician rather than self-treating.
Which B vitamin deficiency is most common?
In the U.S., B12 is one of the most discussed, especially in older adults and vegans[6]. Folate deficiency has become less common since grain fortification began in 1998[5].
Can low B vitamins cause hair loss?
Riboflavin and biotin deficiencies are both linked to hair loss or thinning[2][7], but true deficiency is rare. See vitamin B complex for hair growth.
Sources
- National Institutes of Health, Office of Dietary Supplements. Thiamin: Fact Sheet for Health Professionals. Updated February 9, 2023. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Riboflavin: Fact Sheet for Health Professionals. Updated May 11, 2022. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Niacin: Fact Sheet for Health Professionals. Updated November 18, 2022. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Vitamin B6: Fact Sheet for Health Professionals. Updated June 16, 2023. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Folate: Fact Sheet for Health Professionals. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. Updated July 2, 2025. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Biotin: Fact Sheet for Health Professionals. Updated January 10, 2022. ods.od.nih.gov
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
