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evidence · mechanism · dose
Supplements/Vitamin

Biotin (Hair Dose)

B-vitamin used cosmetically for hair and nail growth.

Skin, Hair & Nails

Overview

B-vitamin used cosmetically for hair and nail growth.

Natural sources
    Common forms

      Forms & variants of Biotin (B7)

      Different chemical forms of Biotin (B7) behave differently. Browse each form's mechanism, bioavailability, and best-use context.

      Parent
      Biotin (B7)

      Coenzyme for carboxylases — popular for hair and nails despite weak data outside true deficiency.

      Mechanism of action

      Cofactor for carboxylase enzymes; influences keratin gene expression.

      Pathways

        Effects on the body

        Organ system effects

        Evidence-based benefits

        Improves brittle nails

        Moderate evidence

        Hair benefits only in deficiency

        Limited evidence

        Potential side effects

        Common
          Rare
          • · Acne with very high dose
          Serious
          • · Interferes with thyroid, troponin labs

          Drug interactions

          No notable interactions reported.

          Supplement interactions

          Pairs well with

          None listed.

          Avoid combining with

          No specific avoidances listed.

          Dosing & bioavailability

          Typical dose
          2500–5000 mcg
          With food?
          Either

          Where to buy

          Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

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          iHerb
          Global delivery · curated brands
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          Thorne
          Practitioner-grade · NSF tested

          Scientific evidence (9)

          CohortCutis · 1993

          Biotin for brittle nails

          Hochman LG, et al.

          Open trial in 35 patients with brittle nails.

          Key findings

          2.5 mg/day biotin increased nail thickness by 25% on average.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — Improves brittle nails

          Live PubMed search

          Live results for "Biotin (Hair Dose) Improves brittle nails" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "Improves brittle nails". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — Hair benefits only in deficiency

          Live PubMed search

          Live results for "Biotin (Hair Dose) Hair benefits only in deficiency" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "Hair benefits only in deficiency". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — randomized controlled trial

          Live PubMed search

          Live results for "Biotin (Hair Dose) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — meta-analysis

          Live PubMed search

          Live results for "Biotin (Hair Dose) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — pharmacokinetics

          Live PubMed search

          Live results for "Biotin (Hair Dose) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — safety adverse events

          Live PubMed search

          Live results for "Biotin (Hair Dose) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Biotin (Hair Dose) — dose response

          Live PubMed search

          Live results for "Biotin (Hair Dose) dose response" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          Opens current human and preclinical literature matching Biotin (Hair Dose) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

          Open study
          Systematic reviewGoogle Scholar · 1970

          Google Scholar: Biotin (Hair Dose) — clinical evidence

          Live Scholar search

          Cross-database citation index for Biotin (Hair Dose) as it relates to "clinical evidence".

          Key findings

          Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

          Open study
          Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.