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Biotin Deficiency Symptoms: Best Biotin Dosage for Hair Growth

What is Biotin Good for?

Recommended dosages of biotin are made for people with normal hair, skin, and nails; however, not everyone absorbs and utilizes biotin the same way and there are instances when someone may need to take more biotin.

Some specific problems that may call for increased biotin intake include brittle nails, uncombable hair syndrome, and poor skin and hair growth. Read more to find out when you will need to take more biotin than the recommended dosage.

What is Biotin Good for?

Biotin Deficiency

There are many reasons for biotin deficiency including: poor diet, malabsorption issues, an alcohol dependence, medication use, as well as people with a rare genetic disorder called biotinase deficiency that naturally predisposes them to low biotin levels.

Certain medications may also affect biotin levels. For example, anti-seizure medications used for treating epilepsy may significantly lower your natural biotin levels. Antibiotics and accutane can also contribute to low biotin levels.8

Raw egg whites are also known to contain a glycoprotein known as avidin that binds to dietary biotin and can prevent it from being absorbed into the gastrointestinal tract.

Poor Skin and Hair Growth

If you are experiencing poor, skin, and hair growth, you may want to consider taking a biotin supplement.

Biotin deficiency causes thin hair9 and approximately 38% of women complaining of hair loss have biotin deficiency. Treating these women with 5,000 mcg biotin/day improved hair growth.8 However, other causes of hair loss such as thyroid problems or androgenetic alopecia should be ruled out before starting biotin.

While not many studies on the effects of biotin on hair growth have been performed, there have been studies on the effects of biotin on hair growth in animals.

In a collaborative study with veterinary surgeons, 119 dogs with poor fur growth and skin conditions were treated with biotin. Dogs treated had dull coats, loss of hair, brittle or breaking hair, pruritis (chronic itchy skin), dermatitis (general skin inflammation), and scaly skin.

The dogs were given 5 milligrams of biotin per 10 kilograms of body weight per day for a period of 3 to 5 weeks. The equivalent dose in humans would be 37,500 mcg per day for the average 75 kg human.

By the end of the study, 60 percent of the dogs showed improvement. In 31 percent of cases, improvements were statistically significant. Only 9 percent of the dogs studied showed no effect from the treatment. These results suggest that biotin may be an effective treatment for fur and skin conditions in dogs.7

    Biotin Vitamins

    Brittle Nails

    Studies document the oral application of biotin to help horses and swine with defects in their hooves and claws, which generally have the same structure as human nails. Using the same idea, researchers conducted a study on 71 participants suffering from human dystrophic fingernails, or onychodystrophy, a condition that refers to any alteration of nail morphology. Each participant was given a dosage of 2,500 mcg of biotin per day.

    By the end of the study, 45 of the 71 participants could actually be evaluated. Of those 45, 41 showed a definite improvement, exhibiting harder, firmer fingernails after about five and a half months. None of those participating considered the treatment ineffective. These results suggest that biotin can potentially provide an effective treatment for patients suffering from dystrophic fingernails or brittle nails.4

    Uncombable Hair Syndrome

    Uncombable hair syndrome is a rare genetic disorder that affects a person’s hair shaft. The disorder results in straw-colored or silvery-blond hair that stands out from the scalp and cannot be combed flat. It is often associated with other health conditions, including Bork syndrome, ectodermal dysplasia, and Angel-shaped phalangoepiphyseal dysplasia.5

    In a small study, researchers studied three children with uncombable hair syndrome. Under a microscope, the participants’ hairs appeared normal, though electron microscope found that each hair shaft was triangular in cross section and featured longitudinal canal-like depressions. One participant was given a dose of 300 mcg of biotin three times per day (900 mcg total per day). After 4 months, the participant showed increased hair growth rate, strength, and combability, though the triangular structure stayed the same. The other two patients, who had ectodermal dysplasia, showed slow improvements in hair appearance and combability over the course of five years without the use of biotin. This study suggests that oral administration of biotin may help to support hair growth and reduce symptoms of uncombable hair syndrome.6

    Low levels of biotin in your blood can cause a variety of problems, most commonly thinning hair and rashes around the nose, mouth, and eyes. Other symptoms may include:

    • Tingling in the arms and legs
    • Depression
    • Hallucinations
    • General lack of interest1
    • High acid levels in urine and blood
    • Skin infection
    • Seizures
    • Nervous system disorders2

    Consuming Raw Egg Whites

    Excessive consumption of raw eggs can also cause biotin deficiency.

    A study found that a boy suffering from basal ganglia lesions caused by biotin deficiency had been eating raw eggs every other day for over a year. The boy was advised to stop eating raw eggs and given a daily oral dose of biotin at 5,000 mcg per each kilogram of body weight. Within four days, the boy showed significant recovery.3

    Raw egg whites contain a compound called avidin which binds to biotin and prevents it from being absorbed. Cooking eggs destroys the avidin protein so consumption of cooked eggs should not cause biotin deficiency.

    Biotin Dosage

    As biotin deficiency is rare, there is no official recommended dietary allowance suggested by the FDA. However adequate intake—referring to intake that is assumed to provide nutritional adequacy—for adult men aged 19 and up is 30 micrograms per day.

    Biotin is a relatively safe vitamin as it is water-soluble and well tolerated. As biotin is a water-soluble vitamin, any excess amount is naturally flushed out of the body via urine. 

    While biotin overdose has not been well published in the scientific literature, some people may experience minor side effects from taking biotin for hair growth such as acne, nausea, diarrhea, and abdominal cramps. You may be able to reduce the risk of side effects from a biotin overdose by:

    • Taking biotin supplements with food
    • Staying hydrated
    • Knowing the foods in your diet that are rich in biotin

    Sources of Biotin 

    Biotin is readily available in a variety of foods. Foods that are naturally high in biotin include:

    • Eggs
    • Organ meats
    • Fish
    • Sweet potatoes
    • Nuts and seeds

    Biotin can also be taken in the form of supplements. The absorption rate of biotin is 100 percent, even at doses up to 20 mg per day.


    Biotin is generally safe even at high dosages. Side effects of biotin are minimal and easily reversed because excess biotin is easily passed by the body through urine.

    We recommend taking 500 mcg-5,000 mcg of biotin per day to support healthy hair, skin, and nails. However, if you find that biotin is causing sudden acne breakouts or a skin rash, considering reducing your dose or taking the vitamin less often.

    Our HairOmega DHT Blocker also comes in a biotin-free version for customers more sensitive to biotin.