Biotin for Nails: Does It Actually Help Brittle Nails?

What biotin is

Biotin is vitamin B7. Your body uses it to turn food into energy and to build keratin, the protein that nails and hair are made of. Adults need about 30 micrograms a day, according to the NIH. Eggs, salmon, meat, nuts, seeds and sweet potatoes all supply it, and gut bacteria make some too. Most people get enough from food without trying.

What "brittle nails" means

Doctors use the term for nails that split in layers at the tip, crack down their length, peel, or break before they grow out. It is common, affecting roughly 1 in 5 people, and women more than men.

What the studies found

• A Swiss study (1990) followed people with brittle nails who took daily biotin. Under an electron microscope, nail thickness increased by about 25% and splitting decreased.
• A US study (1993) looked back at 35 patients who had taken biotin for brittle nails. About two thirds reported improvement.
• An earlier small study (1989) reported firmer, harder nails in most of the people who took it for several months.

All three were small. None used a placebo group, so there is no way to know how many of those nails would have improved anyway. No large controlled trial has been done since. A 2017 review of the published cases found that the clearest benefits were in people with an underlying problem, such as a true deficiency or a diagnosed nail condition.

Who is most likely to benefit

• People who are low in biotin. True deficiency is rare. It is more likely with heavy alcohol use, certain seizure medications, some gut conditions, pregnancy, or a diet heavy in raw egg whites, which block biotin absorption.
• People with diagnosed brittle nail syndrome who have already ruled out other causes.

If your biotin level is normal and your nails are healthy, extra biotin has not been shown to make them stronger.

How long it takes

Fingernails grow about 3 millimeters a month. A nail takes around six months to replace itself from base to tip, and toenails take a year or more. Biotin cannot repair the nail you already have. Any benefit shows up in the new nail growing in. That is why the studies ran for several months, and why judging it after three weeks tells you nothing.

The lab-test warning

High-dose biotin can interfere with blood tests. The FDA has warned that it can cause falsely high or falsely low results on tests that include thyroid panels and troponin, the test used to diagnose a heart attack. Beauty supplements often contain hundreds of times the daily requirement.

Tell every provider who orders blood work that you take biotin. You may be asked to stop for a few days before the draw.

What else causes brittle nails

For most people the cause is on the outside of the nail, or it is something a blood test can find.

• Water and chemicals. Repeated wetting and drying is the most common cause. Dishwashing, cleaning products, hand sanitizer and acetone polish remover all dry the nail plate.
• Age. Nails get drier and grow more slowly over time.
• Low iron. Iron deficiency can cause thin, spoon-shaped or brittle nails. A ferritin test finds it.
• Thyroid problems. Both an underactive and an overactive thyroid affect nails.
• Skin conditions, including psoriasis and eczema.
• Nail fungus, which causes thick, crumbly, discolored nails and needs its own treatment.
• Not enough protein or very low-calorie dieting.

If your nails changed suddenly, changed color, or separated from the nail bed, see a doctor or dermatologist.

What helps, with or without biotin

• Wear gloves for dishes and cleaning.
• Moisturize hands and nails after washing, and again at night.
• Keep nails short and file in one direction.
• Use acetone-free remover, and take breaks from gel and acrylics.
• Eat enough protein.
• Get iron and thyroid checked if brittle nails come with tiredness, hair thinning or feeling cold.

Pill or shot?

A pill is the form used in every nail study. Biotin is absorbed well by mouth, so for most people a pill is enough. A biotin shot is an option for people who do not absorb well through the gut or who will not take a daily pill. There are no studies showing that a shot works better for nails than a pill does.

Where Zen IV Spa fits

We offer a Beauty Biotin Shot, and vitamin injections that can be shipped to you after a provider's video visit. If your nails are brittle and you are also tired or losing hair, the more useful first step is a blood draw at home to check iron, thyroid and vitamin levels. A licensed nurse comes to you anywhere in New York & New Jersey, and a licensed provider reviews the results with you. Our medical director oversees every treatment.

Related reading: Does Biotin Help Hair Growth?

Quick answers

Does biotin strengthen nails? It may, in people with brittle nails. The evidence is three small studies without a placebo group.

How long until I see a difference? Three to six months, because only new nail growth can change.

Will it help if my nails are already healthy? There is no evidence that it does.

Is biotin safe? It is generally well tolerated, and extra is passed in urine. The main risk is wrong results on blood tests.

Should I stop biotin before a blood test? Tell the provider you take it and follow their instruction. A few days off is commonly advised.

What is the most common cause of brittle nails? Repeated wetting and drying of the hands, followed by age.

Brittle nails and tired all the time? Book a blood draw at home at zenivspa.com/labs-testing/.

All treatments are medical services. Every guest is screened, and every treatment is provided only under the clearance, prescription or standing protocol of a licensed medical provider. Compounded peptides are not FDA-approved unless stated. Nothing on this page is a diagnosis or a promise of results.