The hair, skin and nails vitamin the experts keep telling people to skip. What biotin is, what the research shows, why it can throw off blood tests, and what 5 skincare experts said about it on camera.
Biotin gummies promise longer hair, stronger nails and better skin, and they are everywhere. So should you be taking them? Will they help with shedding? Can they cause breakouts? And what is the harm in trying?
The straight answer is a clear no from the experts, unless a doctor has found that you are short of biotin. Real deficiency is rare, and the reviews found no good evidence that extra biotin helps hair, skin or nails in people who already get enough.
So biotin's Guru Score is 0%. That may look harsh for a vitamin your body genuinely needs, but the score is about taking extra biotin for hair, skin and nails, not about biotin itself. The experts also flag a real downside: high-dose biotin can make some blood tests read wrong, including tests for a heart attack and for thyroid problems. Below, what the experts said sits next to what the studies and the US Food and Drug Administration (FDA) say, so you can see where the two line up.
Biotin (vitamin B7) is a B vitamin sold as a supplement for hair, skin and nails. The experts we track advise against taking it for those reasons. Reviews of the research found no good evidence that biotin helps hair, skin or nails in people who are not deficient, and deficiency is very rare in healthy people who eat a balanced diet [1, 3, 4]. The FDA warns that biotin above the recommended daily intake can cause falsely high or falsely low results on some lab tests, including troponin tests used to diagnose heart attacks [6, 7].
| Question | What we found |
|---|---|
| What is it? | Vitamin B7, a water-soluble B vitamin found in foods such as egg yolk, liver and cereals, and made in small amounts by gut bacteria [4]. |
| Do skincare experts recommend it? | No, not unless a doctor finds you are deficient. |
| Does it grow hair? | Not in people who have enough already. The evidence for a benefit comes from people with an underlying deficiency or condition [1, 2]. |
| Is deficiency common? | No. It is very rare in healthy people who eat a balanced diet [4]. |
| How much do adults need? | About 30 micrograms a day, the intake recommended for adults [4]. |
| The main risk | Wrong results on some blood tests, including troponin (heart attack) and thyroid tests [6, 7, 8]. |
Biotin, also called vitamin B7 or vitamin H, is a B vitamin your body uses to help make and break down fats, sugars and proteins. You get it from food such as egg yolk, liver, cereals, vegetables and rice, and the bacteria in your gut make some too. The recommended intake for adults is about 30 micrograms a day [4].
Biotin earned its beauty reputation because a real shortage of it shows up on the outside: thinning hair, brittle nails and a scaly rash on the face [4]. The leap from there is that more biotin must mean better hair. That is where the experts and the research part ways with the marketing.
Biotin is found in multivitamins, prenatal vitamins and supplements marketed for hair, skin and nail growth [6]. This guide is about those oral supplements.
Here is what each of them said on camera, with a link to the moment they said it.
While there is a small amount of research to suggest that biotin supplement may be helpful for those of you who deal with brittle nails, there's an absence of research to support taking biotin for hair growth or for the skin in the absence of a confirmed biotin deficiency, which by the way is super super rare.Watch ▸
Using a Biotin supplement to grow your hair [...] is a hair care myth that just won't go away. [...] If you are truly deficient in biotin, supplementing with biotin will help you grow your hair, however it is exceedingly rare, so rare that I have never had a patient be biotin deficient.Watch ▸
I do not recommend this because of the potential harms from biotin supplementation. Laboratory test interference is the most important risk that you really need to understand. Biotin interferes with many common blood tests including thyroid function tests like TSH, T3 and T4. It can interfere with troponins which are used to diagnose heart attacksWatch ▸
I've used biotin in the past, I saw no results. A lot of people promote biotin as this miracle thing for growing hair and nails, but a lot of the medical science doesn't back that up, and when I was taking just pure biotin, it just didn't do much for me.Watch ▸
Some people think that biotin can make acne worse, but there's still very limited data on that, so I don't really talk about that as much with patients.Watch ▸
The experts are not weighing up pros and cons here. The detail is in why they say no.
Not much in its favour. A 2017 review that set out to systematically search the literature found 18 reported cases of biotin helping hair or nails. In each one, the person had an underlying problem behind poor hair or nail growth, such as a biotin deficiency, brittle nail syndrome or a rare condition called uncombable hair syndrome. The authors concluded there is not enough evidence for biotin in healthy people [1].
A second 2017 review went further for hair: at that point there had been no clinical trials of biotin for hair loss of any kind, and no randomised controlled trial of its effect on hair quantity or quality. It noted that biotin's popularity is far out of proportion to the evidence [2]. A 2021 review of supplements used in dermatology reached the same place: the current evidence is not enough to recommend biotin [3].
Newer work has not changed the picture much. A 2025 review found the evidence in healthy people with no underlying deficiency very limited, and described one small trial in 10 healthy men, run for 14 days alongside topical minoxidil, as too small and short to draw conclusions from [4].
Nails are the one place with a hint of support, which is why some of our experts mention brittle nails. The best known study is a small, retrospective look at 35 people with brittle nails who took biotin daily: 22 of them (63%) improved, judged by eye, and 13 saw no change [5]. That study cites an earlier Swiss study reporting thicker nails with biotin [5]. Small, uncontrolled studies like these are a hint, not proof.
Biotin works when there is a real shortage to fix. Deficiency can come from eating large amounts of egg white, long-term tube or drip feeding without biotin, some medicines (certain anti-seizure drugs, oral antibiotics and isotretinoin) and heavy long-term drinking [4]. There is some evidence that biotin helps the hair loss linked to one anti-seizure medicine, valproic acid [4]. These are situations for a doctor to diagnose, not something a hair gummy is designed for.
Yes, and this is the point the experts stress most. Many lab tests use biotin as part of how they work, including hormone tests and tests for troponin, a marker of heart damage. The FDA says that biotin in the blood of people who take more than the recommended daily intake can cause falsely high or falsely low results, depending on the test, and that wrong results can lead to misdiagnosis. It raised the concern in safety communications in November 2017 and November 2019 [6].
Troponin is the worrying one. The FDA says it has continued to receive reports of biotin causing falsely low troponin results [7], which could make a heart attack look like something else. In one lab study, 10 mg of biotin a day was enough to interfere significantly with one widely used troponin test, while two other troponin tests were unaffected [9].
Thyroid tests can be affected too. In a study where 13 adults took 10 mg of biotin a day for eight days, results for TSH and thyroid hormones changed on one testing platform, and thyroglobulin read falsely low on another. The interference was greatest two hours after a dose [8]. A 2025 review lists pregnancy (hCG) tests, vitamin D and HIV tests among others that can be affected [4].
Tell the doctor or nurse ordering the test each time, and mention any hair, skin and nails supplement or multivitamin as well. A 2025 review notes it is recommended to stop biotin at least 48 hours before lab tests [4], but ask your doctor what is right for the test you are having. In an emergency, telling the team you take biotin is what matters.
This is where the experts do not line up neatly. Dr Dray says she has seen breakouts in people taking high-dose biotin, and that patients and viewers have told her the same. Dr. Mamina says some people think biotin can make acne worse, but that the data is very limited, so she does not raise it much with patients.
We looked for published studies of biotin causing acne and did not find a controlled study that settles it. So treat it as something some dermatologists report seeing, not an established side effect. If you start a biotin supplement and break out, it is a reasonable thing to mention to your doctor.
For most people, the experts say no. If your hair is thinning or shedding, the useful step is finding out why. Dr. Sam Ellis points out that hair often regrows on its own after a big shed, and that it is easy to credit whatever you started taking at the time. A dermatologist can check for the causes that do respond to treatment.
If a doctor has found a biotin deficiency, or you have a condition where biotin is part of the treatment, take it as they advise. Otherwise, the experts' view is that the supplement is unlikely to help, and the blood test problem is a real cost [6, 7].
Not unless you are deficient. A 2017 review found the reported cases where biotin helped hair or nails were in people with an underlying problem, and concluded there is not enough evidence for healthy people [1]. Another review found no clinical trials of biotin for hair loss at the time [2]. The experts we track agree.
Possibly, but the evidence is thin. In a small, retrospective study of 35 people with brittle nails, 63% improved on daily biotin, judged by eye, and the rest saw no change [5]. Dr Dray describes the research for nails as small and a reach. If your nails are brittle, a dermatologist can look for the cause first.
There is no good evidence it does in people who are not deficient. A 2021 review of supplements used in dermatology found the evidence not enough to recommend biotin [3]. A real deficiency can cause a scaly facial rash [4], but that is rare, and it is a reason to see a doctor rather than to take biotin just in case.
No. It is very rare in healthy people who eat a balanced diet [4]. It can happen with large amounts of egg white, long-term tube or drip feeding without biotin, some medicines (certain anti-seizure drugs, oral antibiotics, isotretinoin) and heavy long-term drinking [4]. Dr. Sam Ellis says she has never had a patient who was biotin deficient.
Thinning hair, brittle nails and a scaly rash on the face are the classic signs [4]. Those symptoms have many other, more common causes, so they are not a reason to self-diagnose. If you have them, see a doctor, who can work out what is behind them.
The recommended intake for adults is about 30 micrograms a day, and most people get that from food such as egg yolk, liver, cereals and vegetables [4]. The studies that found lab test interference used 10 mg a day [8, 9], which is more than 300 times that amount.
Yes. The FDA warns that biotin above the recommended daily intake can cause falsely high or falsely low results on tests that use biotin, including hormone tests and troponin tests used to diagnose heart attacks [6, 7]. Studies have shown 10 mg a day can affect some thyroid and troponin tests [8, 9]. Some tests are not affected, but you cannot tell which ones from the outside.
Ask the doctor ordering the test, and always tell them you take biotin. A 2025 review notes it is recommended to stop at least 48 hours before lab tests [4]. In a thyroid study, interference peaked two hours after a dose [8]. In an emergency, telling the team you take biotin matters more than anything else.
It is not settled. Dr Dray reports seeing breakouts in people on high-dose biotin, while Dr. Mamina says the data on it is very limited. We did not find a controlled study that answers it. If you break out after starting a biotin supplement, mention it to your doctor.
Not for the biotin. The reviews found no good evidence that biotin helps hair in people who are not deficient [1, 2, 3]. Dr. Sam Ellis makes the point that when a hair supplement works, it is not because it contains biotin. Whatever you take, check the biotin content and tell your doctor before any blood test [6].
Biotin is a normal part of many prenatal vitamins [6], so ask your doctor or midwife before adding a separate high-dose supplement. One practical point: a 2025 review lists pregnancy hormone (hCG) tests among the tests biotin can interfere with [4], so mention any biotin you take when you are tested.
The dermatologists among our experts do not, unless you have a diagnosed deficiency. Dr Dray, Dr. Sam Ellis and The Budget Dermatologist say no, as does Cassandra Bankson, a medical esthetician, and Dr. Mamina's take on biotin and acne is cautious.
5 experts, 16 mentions, every one traced to a video you can watch. Sponsored takes are excluded.
This guide combines two kinds of information. The expert consensus comes from 16 mentions of biotin supplements by 5 skincare experts in their YouTube videos. Each one was read, given a Yay, Mixed or Nay verdict and linked to the moment it was said. Sponsored takes are excluded. The research sections summarise published studies, FDA guidance and medical sources, listed in full above.
The Guru Score measures how warmly the experts talk about biotin. It is not a measure of clinical effectiveness, and this guide is not medical advice. It has not been reviewed by a doctor.
This guide is general information, not medical advice. The Guru Score reflects how warmly the experts we track talk about biotin; it is not a measure of clinical efficacy. Speak to a dermatologist or doctor about a diagnosed skin condition, and before using any medicine.