A biotin deficiency may lead to hair loss, and supplements may aid hair growth. However, evidence has not shown that biotin supplements can boost hair growth in those without a deficiency.

Biotin is an essential B vitamin that helps the body get energy and nutrients from carbohydrates, proteins, and fats.

It is a critical vitamin for bodily function. Many foods — including egg yolks, nuts, and legumes — contain small amounts of biotin. Bacteria in the large intestine also produce biotin. A person will usually get enough biotin from these two sources.

However, additional supplementation may be necessary during pregnancy or if a person has a biotin deficiency.

Some people recommend biotin supplementation to aid hair growth. However, there is no clinical evidence to support its use for this purpose.

This article will discuss the impact that biotin has on hair growth. It will also look at recommended intakes, possible side effects, and the impact of deficiency.

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Anecdotal claims that biotin can aid hair growth are common, and its popularity among consumers is high.

However, according to a 2017 analysis of available studies, there have not been any clinical trials to support the use of biotin supplementation to improve hair health, except in people with deficiencies.

Although some older studies have suggested links between biotin deficiencies and alopecia, further analysis has not found conclusive proof of benefit among healthy individuals.

People should always speak with a doctor before taking any supplements.

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The Food and Drug Administration (FDA) does not have a daily recommended dietary allowance for biotin. However, according to estimates, an intake of 30 micrograms (mcg) may be adequate.

The average intake of biotin in Western countries, excluding the United States, is an estimated 35–70 mcg per day.

It is rare for a person to have a biotin deficiency, and most people in the U.S. naturally get enough from gastrointestinal bacteria and a balanced diet.

Can you take too much biotin?

Most people get adequate amounts of biotin from internal production and diet. Scientists have not established a tolerable upper intake level for biotin.

However, people with biotin deficiencies and those who are pregnant or breastfeeding may require biotin supplementation.

Healthcare professionals may prescribe a dosage of 5 milligrams (mg) per day for a person with a biotin deficiency, according to an older 2016 study. However, the range of required supplementation may differ depending on individual circumstances.

Biotin might interfere with certain laboratory tests. A high concentration of biotin in samples may compromise diagnostic tests in which biotin is a key component.

This may be the case for tests looking at troponin levels and thyroid function. According to an analysis, most biotin-related false results occur in thyroid disease-related tests.

People should let their doctor know if they are taking any supplements before undergoing any diagnostic tests.

Research suggests that having excess levels of biotin in the body is rare. However, symptoms of biotin overdose may include excessive thirst, insomnia, and increased urination.

Individuals with diabetes should speak with a healthcare professional before taking biotin supplements. A 2022 review of research found that biotin supplements lowered fasting blood sugar but not hemoglobin A1C in people with type 2 diabetes.

Due to the body’s reliance on internal production and dietary intake for biotin levels, anything that causes malnutrition or interferes with gastrointestinal function can contribute to the development of a biotin deficiency.

The metabolic requirements of pregnancy may also lead to biotin deficiencies in some cases, according to older 2014 research. Medical guidance has also suggested that genetic conditions affecting intestinal bacteria balances may result in biotin production deficiencies.

Other factors that can contribute to biotin deficiencies include:

  • too much avidin, which is a compound present in foods such as raw eggs that impairs biotin absorption
  • long-term use of anticonvulsant medications
  • gastrointestinal conditions that prevent the absorption of biotin
  • chronic use of alcohol or intravenous drugs
  • isotretinoin, which is an acne medication
  • gastrectomy or partial gastrectomy
  • antibiotics
  • smoking

Foods with a notable concentration of biotin include:

Various other nutritional supplements could improve hair health. However, human trials have not supported the efficacy of many of these remedies for this purpose.

Some popular nutrients that may also help with hair growth and thickness include:

People should always speak with a healthcare professional before taking any dietary supplements, as they may cause side effects in large doses or interact with medications or other supplements.

There is no firm scientific evidence to support the use of biotin supplements to improve hair growth unless a person has a biotin deficiency.

Although there is little evidence of direct health consequences of biotin supplementation, excessive intake may interfere with laboratory test results.

Many other available natural remedies may support hair growth. However, like biotin, many of these are not scientifically proven to have a positive effect.

It is important for individuals experiencing unexpected or unusual hair loss to speak with a doctor. In most cases, biotin deficiencies are not the cause of hair loss, but they may be a contributing factor.