Biotin

Overview

Biotin (vitamin B7, sometimes called vitamin H) is a small water-soluble vitamin produced naturally by gut bacteria and present in many foods. The cosmetic ingredient is a white crystalline powder, usually sold pre-dissolved in propylene glycol or pentylene glycol for easier formulation, or in liposomal carriers for enhanced skin delivery.

A clarifying note on the marketing context: biotin’s strongest evidence is for oral supplementation when there is documented biotin deficiency or specific clinical conditions. The “biotin for hair growth” supplement industry has overstated the case considerably — for adults without deficiency, oral biotin supplements show no consistent hair-growth benefit in well-controlled studies.

Topical biotin is a different question. There is modest evidence that topical biotin in hair and scalp products can:

• Strengthen the keratin in the hair shaft over weeks of consistent use
• Modestly support nail strength when used in nail-treatment products
• Support skin barrier function in deficient skin (rare in normal populations)

The benefits are real but not dramatic. Position biotin in formulas as a supporting ingredient, not as a hair-growth miracle.

Shelf life is 18-24 months for the powder; 12-18 months for pre-solubilised liquid versions.

What it does in a formula

• Hair keratin support — topical application strengthens the protein structure of the hair shaft
• Nail strengthening — modest evidence for nail-product use
• Skin barrier support in deficient skin
• Marketing positioning for hair and nail wellness product lines

It is most useful in leave-on hair products and nail treatments, where the long contact time gives the biotin time to interact with the keratin.

How to use

Biotin is poorly water-soluble in its raw form. Most formulators use pre-solubilised commercial versions (biotin in pentylene glycol or in liposomes). Add to the cool-down phase, below 40 C.

Usage rates by product type:

• Leave-in hair conditioners: 0.5-1%
• Scalp serums: 0.3-1%
• Rinse-off hair conditioners and masks: 0.5-1%
• Nail strengtheners and cuticle oils: 0.5-1%
• Eyelash and eyebrow serums: 0.3-1%
• Skin products (where deficiency is suspected): 0.1-0.5%

It pairs naturally with d-panthenol (hair amplifier), with caffeine (scalp circulation), with peptides like procapil or capixyl (hair growth combinations), and with hydrolysed keratin.

Best for / Worst for

Best for: hair growth and density products, scalp serums, nail strengtheners, eyebrow and eyelash serums, hair masks for damaged hair, products targeting customers concerned about hair thinning.

Worst for: general face skincare (modest topical benefit unless deficiency is documented), formulations claiming dramatic hair regrowth (the evidence does not support that level of claim).

Common pitfalls

Solubility. Raw biotin powder is poorly water-soluble. If you add it as a powder to a water phase, it can clump and fail to disperse. Use pre-solubilised commercial preparations.

Overstating activity. Biotin is one of the most over-marketed hair-care ingredients. Be accurate: it is a supporting ingredient that helps strengthen hair keratin over weeks of consistent use. It will not regrow lost hair.

Confusing oral and topical. Oral biotin (for diagnosed deficiency) and topical biotin (for hair and nail surface strengthening) are different applications. Most consumer confusion stems from supplement marketing claims being conflated with topical product claims.

Substitutes

• D-panthenol (provitamin B5) — alternative B-vitamin with stronger evidence for hair benefits.
• Hydrolysed keratin — direct keratin protein for hair shaft strengthening.
• Niacinamide (vitamin B3) — broader skin benefits, less hair-specific.
• Hair-growth peptides (Procapil, Capixyl) — concentrated active alternatives for measurable hair improvement.
• Castor oil — traditional hair-strengthening oil with no biotin but real effects on keratin.