Biotin: there has never been a clinical trial of it for hair loss

Biotin is a water-soluble B vitamin, also called vitamin B7 or vitamin H. It is an essential cofactor for several carboxylases involved in the metabolism of fatty acids and amino acids and in gluconeogenesis.

There is no efficacy badge on this page. And the reason is exactly the reason this site exists.

In 2017 a review went through all the pertinent literature on biotin supplementation for hair growth and hair quality. The same paper also investigated the ingredient's popularity through market analytics.

Setting those two figures side by side is what the paper did. Its title says so — 'The infatuation with biotin supplementation: is there truth behind its rising popularity? A comparative analysis of clinical efficacy versus social popularity.'

And here is what it found.

• no clinical trial has been conducted to investigate the efficacy of biotin supplementation for alopecia of any kind
• nor has there been any randomised controlled trial of its effect on hair quality and quantity in human subjects

This is not 'the evidence is thin'. It is 'there are no trials'. Few ingredient pages on this site carry that sentence.

So why make this page. Biotin is the most widely sold ingredient in supplements for hair and nails. If this site is a place that records the distance between what is sold and what has been established, it cannot leave out the item where that distance is longest.

Where this site does attach thick evidence on hair loss is elsewhere. Minoxidil is one of the few items here carrying 'strong evidence', and PRP and low-level laser therapy have trials attached too. The hair loss page gathers those places together.

• There is no basis for writing a dose. With no clinical trial for hair, there is no trial dose for this site to carry across. We do not estimate one.
• If you are looking at hair loss, start where the evidence is. Minoxidil carries 'strong evidence' here. PRP and low-level laser therapy have trials too.
• Establish the cause of the hair loss first. Male and female pattern, patchy, traction, and loss driven by systemic illness or a medicine are all different. Start from the hair loss page.
• If you are due a blood test, say that you are taking it. See cautions below.
• Trials of topical biotin are not on this page either.

• This is the most important caution on the page — biotin can distort blood test results. Several assays are designed around biotin, and results can come out other than the truth. Thyroid function tests and cardiac markers are the ones most often raised. A misread result means a missed condition, or treatment for one you do not have.
• So say that you are taking it before a blood test. Supplements often do not get counted as 'medicines' and drop out of the history. Say it first.
• It is commonly explained that a water-soluble vitamin simply leaves the body in excess, but the test interference above happens regardless of that explanation.
• Check use in pregnancy or breastfeeding in a clinic.
• If hair is falling suddenly and heavily, if the scalp is inflamed or scarred, or if it comes out in patches, seek care before picking a supplement. Different causes need different things.