Vitamin B12 for Hair: What the Research Shows
Vitamin B12 deficiency can affect the skin, hair and nails, but most people with hair thinning don't have a B12 problem. Studies of women with telogen effluvium found B12 levels similar to comparison groups, and a review of nutrient deficiencies lists B12 among many that can show up in hair.
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Key Takeaways
- A dermatology review lists hair and nail changes among the skin signs of cobalamin (B12) deficiency, alongside hyperpigmentation and mouth changes.
- In 108 women with diffuse hair loss, vitamin B12 levels were similar between acute and chronic telogen effluvium and showed no significant correlation with phototrichogram findings.
- A review of micronutrient deficiencies lists B12 among the B vitamins that can cause skin, hair and nail abnormalities, particularly in people with poor absorption or poor diet.
- We found no trial showing that B12 supplements grow hair in people who are not deficient.
What Is Vitamin B12?
Vitamin B12 (cobalamin) is a water-soluble vitamin that is important for blood and the nervous system.
Does B12 Help Hair?
Only, as far as we found, where there is a deficiency. For others, we found no evidence that extra B12 helps hair.
Using B12 Sensibly
- Ask your doctor to test if you have risk factors or symptoms of deficiency.
- Don't self-treat hair loss with B12. Many causes exist.
- Tell your doctor about injections or high doses. The review notes rare skin reactions to B12 therapy.
What The Research Shows
B12 And The Skin
A review of vitamin B12 in dermatology states that altered cobalamin levels can cause skin changes. The cutaneous signs of deficiency include hyperpigmentation (most common), hair and nail changes and oral changes such as glossitis. Complications of cobalamin therapy include acne, rosacea and allergic site reactions, and anaphylaxis with injections (Brescoll and Daveluy, 2015).
Women With Diffuse Hair Loss
In 108 women with diffuse hair loss, split into acute and chronic telogen effluvium, vitamin B12 levels were similar between the groups and had no significant correlation with phototrichogram findings. Ferritin was found to have an important role in diffuse hair loss (Bilik et al., 2024). This study didn't include a no-hair-loss comparison group.
Deficiency Signs
A review of micronutrient deficiencies noted they commonly cause abnormalities of skin, hair and nails, and may be present in people with impaired absorption or poor dietary intake. B vitamins including riboflavin, niacin, pyridoxine, biotin and B12 are among those most commonly presenting with skin findings (DiBaise and Tarleton, 2019).
See also: Biotin vs Prenatal Vitamins for Hair Growth: What the Evidence Shows · Selenium and Hair: What the Research Shows
To see how this fits with the other nutrients hair needs, read our guide to the best vitamins for hair growth.
Vitamin B12 is one of the ingredients in FullyVital's Hair Revival Supplements. For how the evidence for each ingredient in the line stacks up, see our evidence-tier breakdown.
Frequently Asked Questions
Does low B12 cause hair loss?
Reviews list hair changes among signs of deficiency, but a study in women with telogen effluvium found no link between B12 level and hair findings.
Should I take B12 for hair growth?
We found no trial showing it helps hair if you aren't deficient. Ask your doctor.
Who is at risk of low B12?
The review mentions impaired absorption or poor dietary intake.
References
- Brescoll J, Daveluy S. A review of vitamin B12 in dermatology. Am J Clin Dermatol. 2015. PubMed
- Bilik L, Kokcam I, Esen M. Evaluation of the relationship of digital phototrichogram findings of patients with diffuse hair loss with blood TSH, ferritin and vitamin B12 levels. North Clin Istanb. 2024. PubMed
- DiBaise M, Tarleton SM. Hair, Nails, and Skin: Differentiating Cutaneous Manifestations of Micronutrient Deficiency. Nutr Clin Pract. 2019. PubMed
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