Is thiamine (Vitamin B1) supplementation effective for treating hair loss?

Thiamine and Hair Loss

Thiamine (vitamin B1) supplementation is not an effective treatment for hair loss and is not recommended for this indication. There is no evidence supporting thiamine as a standalone therapy for any form of alopecia, and established clinical guidelines for hair loss management do not include thiamine supplementation 1.

Evidence Base

Lack of Support in Hair Loss Guidelines

• The British Association of Dermatologists' guidelines for alopecia areata management make no mention of thiamine or B-vitamin supplementation as a treatment option 1
• Recommended treatments for alopecia areata include intralesional corticosteroids for limited patchy hair loss and contact immunotherapy for extensive disease, with no role identified for vitamin supplementation 1

Limited Research on Thiamine and Hair

• One in vitro study showed that a combination formulation containing L-cystine and thiamine increased keratinocyte proliferation and provided UV protection in growth-limited conditions, but this was a laboratory study using multiple ingredients, not a clinical trial of thiamine alone 2
• A 2023 study of a topical hair serum containing thiamine along with copper, niacinamide, hyaluronic acid, riboflavin, and biotin showed efficacy in female pattern hair loss, but the multi-ingredient formulation makes it impossible to attribute effects to thiamine specifically 3

What the Evidence Actually Shows About Micronutrients

• Comprehensive reviews of micronutrients in hair loss focus on vitamin D, iron, zinc, selenium, and B-complex vitamins (particularly biotin), but do not identify thiamine deficiency as a cause of hair loss 4, 5
• The 2017 American Journal of Clinical Dermatology review on micronutrients in alopecia areata discusses zinc, copper, magnesium, and selenium extensively but does not address thiamine 1

When Thiamine Supplementation IS Indicated

Clinical Contexts Requiring Thiamine

Thiamine supplementation is appropriate only when there is documented or suspected thiamine deficiency, not for hair loss treatment:

• Bariatric surgery patients: Should receive multivitamins containing at least the recommended daily allowance for thiamine, with consideration for 200-300 mg daily for those with symptoms like vomiting or poor dietary intake 1
• Deficiency treatment: Mild deficiency requires 10 mg/day oral thiamine for one week, then 3-5 mg daily for at least 6 weeks; severe deficiency with neurological symptoms requires 500 mg IV three times daily 6
• High-risk populations: Those with malnutrition, prolonged vomiting, alcohol abuse, or rapid weight loss should be assessed for thiamine deficiency 6

Important Caveat

• If a patient with hair loss has adequate thiamine levels and is eating well, thiamine supplementation should be discontinued, as doses exceeding 400 mg daily may cause mild side effects including nausea and anorexia 7
• Thiamine's primary role is in carbohydrate metabolism, cellular respiration, and nervous system function—not hair growth 8

Clinical Bottom Line

Do not prescribe thiamine for hair loss. Instead, evaluate for established causes of alopecia and use evidence-based treatments such as intralesional corticosteroids for patchy alopecia areata or contact immunotherapy for extensive disease 1. If nutritional deficiency is suspected as a contributor to hair loss, assess for deficiencies in iron, zinc, vitamin D, and biotin—not thiamine 4, 5.