Biotin (vitamin B8, also called vitamin H) is a water-soluble B vitamin. Its “beauty vitamin” nickname reflects its real biochemical role: it acts as a coenzyme for carboxylases, enzymes essential to keratin synthesis (the protein making up 95% of hair, 85% of nails and the skin’s outer layer), fatty-acid metabolism that nourishes the scalp and skin hydration, and general energy metabolism. Under EU-authorised health claims, biotin contributes to the maintenance of normal hair, to the maintenance of normal skin, and to normal energy metabolism.

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The recommended intake (NRV) for biotin is 50 µg/day; 5000 µg is far above that, and this is intentional: biotin is water-soluble, so excess is cleared by the kidneys with no accumulation risk (unlike fat-soluble vitamins A, D, E, K). Hair-focused clinical studies typically use doses of 2,500 to 10,000 µg/day, well above the NRV, because visible effects on keratin only appear at these levels; intestinal absorption of biotin is also only partial, so a higher dose compensates for this limited bioavailability.

Important: high-dose biotin can interfere with certain blood tests (thyroid TSH/T4, cardiac troponin). If you need a blood test, stop biotin 3 to 5 days beforehand and inform your lab.

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Hair growth is slow, so patience is needed: 2 to 4 weeks for improved strength and shine of existing hair; 6 to 8 weeks for reduced breakage; 3 to 4 months for visible density and growth improvements; 6 months for full results. Nails typically show results sooner (4 to 8 weeks) since they grow faster than hair — becoming harder, less ridged and less brittle. Consistency matters: one capsule daily, every day, for at least 3 months.

Take 1 capsule per day. For a complete beauty routine, biotin pairs well with zinc bisglycinate (contributes to the maintenance of normal hair, skin and nails), collagen (structural support for the skin), selenium, silicon and iron (iron deficiency is a common cause of hair shedding in women).

Food supplement. Not a substitute for a varied, balanced diet and a healthy lifestyle. Do not exceed the recommended daily dose. Keep out of reach of children.

Does biotin make hair grow faster?

Biotin supports keratin production and the quality of the hair fibre. It does not make hair grow faster than its natural rate (about 1 cm/month), but it strengthens the hair that does grow — more resistant, shinier, less prone to breaking.

Does biotin interfere with blood tests?

Yes, at high doses (5000 µg+). Biotin can distort TSH (thyroid) and troponin (heart) test results. Stop biotin 3 to 5 days before a blood test and inform your lab.

Where can I buy high-dose biotin in Paris?

Biotin 5000 mcg by Doctor’s Best is sold at Herba Barona, 10 rue Théophile Roussel, Paris 12, Tuesday to Saturday, 9:30 am–6:30 pm.

Herba Barona is an independent specialist supplement shop in the heart of Paris — established in 2006. What you order is genuinely on our shelves: we ship from our own stock, with no dropshipping and no long waits.

Visit us at 10 rue Théophile Roussel, Paris 12 — or use Click & Collect and pick up your order in-store. We also deliver across France and Europe. Friendly, expert advice in English from our team.

Where is the shop?

Herba Barona is at 10 rue Théophile Roussel, 75012 Paris — a two-minute walk from Ledru-Rollin (line 8), close to Bastille. Open Tuesday to Saturday, 9:30 am–6:30 pm.

Can I order online or collect in store?

Yes. We ship across France and Europe under the same conditions as our French store, or choose Click & Collect to pick up your order for free at our Paris shop.