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What Are the Most Common Biotin Side Effects?

By Grace A. Zuccarello
Updated Mar 03, 2024
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Biotin, or vitamin B7, is a water-soluble vitamin that typically causes no side effects, even in those who take it in high doses. Those who do experience side effects most often report cystic acne breakouts that clear up when they stop taking the supplement. Certain people also have allergic reactions to it, and taking it with certain medications can make them less effective. Pregnant women should not take biotin without consulting a healthcare professional because of a very low possibility of miscarriage.


The most common biotin side effect is breakouts of cystic acne along the jawline and chin. It's not clear why this happens, but many cases subside after a few weeks, and almost all stop after a person stops taking the supplement. Lowering the dosage to 2,500 mcg or less per day can help decrease this effect, as can drinking lots of water. Different people experience different frequencies of acne with the vitamin, so preventing the problem may involve trial and error to find the right dosage.


Allergic reactions are another of the potential, if uncommon, biotin side effects. Many people who do have allergies to this supplement are also allergic to cobalt and cobalamin (vitamin B12), though this is not always the case. The most common symptoms of a reaction to vitamin B7 are tightness and pain in the chest, swelling in the face and throat, nausea, and an itchy rash. Anyone with these symptoms should seek medical attention immediately, as this type of reaction can be fatal.


Several studies have shown that high doses of biotin given to pregnant rats may increase their risk of miscarriage. It's not clear why this happens, though, or whether it would have the same effect on humans. To be on the safe side, pregnant women should not take B7 supplements without talking to their medical provider first.


Biotin also interacts with some anti-seizure medications and drugs to reduce cholesterol, making them less effective. Additionally, it helps the metabolism, including regulating blood sugar levels and carbohydrate functions, which means that it can have an effect on blood glucose levels when taken in high doses. People taking anticonvulsants, cholesterol-lowering medications, or those with insulin sensitivity or diabetes should consult a medical professional before taking biotin to avoid any potential interactions.

Life-threatening interactions with this substance are extremely rare. The only recorded case is of a woman who experienced a life-threatening lung and chest condition called eosinophilic pleuropericardial effusion after she ingested a large amount of vitamin B7 along with vitamin B5. She recovered once she stopped using both vitamins. It is not known whether her condition stemmed from biotin side effects, vitamin B5 side effects, a combination of the two, or something else.


People can greatly reduce their chance of biotin side effects by taking supplements in the recommended dosage, which is generally around 30 mcg/day for adults and between 5 and 10 mcg for infants and children. Since it's water-soluble, drinking more fluids can also help flush any extra B7 out of the body. Other people prefer to avoid taking biotin in supplement form altogether and get theirs from dairy products, nuts, salmon, and whole grain products.

Does Biotin Cause Weight Gain?

No studies suggest that taking biotin causes weight gain. Some people claim it can have this effect, but they don’t have any scientific evidence to support it. Any claims that biotin increases appetite are only anecdotal, not backed up by science.

Other people claim that biotin supplements can help you lose weight, but that conclusion isn’t supported by studies either. Healthy levels of vitamin B7 may help lower triglycerides and blood sugar, but the results of studies are mixed. You should discuss treatment options for high blood pressure and diabetes with your doctor instead of relying on over-the-counter supplementation.

Can Biotin Cause Hair Loss?

People who have a severe deficiency of biotin can experience problems with hair loss. This effect can start as thinning hair on the scalp, and it can affect both men and women. If the problem is allowed to continue, it can trigger a loss of body hair, including arm and leg hair.

How is biotin linked with hair health? This vitamin helps your body produce keratin, a protein that gives your hair, nails and skin their structure. With sufficient levels of keratin, hair is stronger and less likely to break or fall out. Biotin also appears to increase the rate hair grows naturally.

This doesn’t mean that biotin supplements can increase hair growth. There isn’t much evidence suggesting that taking vitamin B7 supplements can reverse thinning hair unless the hair loss was caused specifically by a biotin deficiency.

Is Biotin Safe for Kidneys?

Biotin isn’t listed as a vitamin of concern for people who have kidney disease. In fact, according to the National Kidney Foundation, your healthcare provider may recommend a B vitamin complex for kidney health. That said, if you have kidney problems, you should discuss any supplements with your doctor before taking them.

What Other Side Effects Can Biotin Supplements Have?

Getting too much vitamin B7 can interfere with thyroid testing results. High levels of biotin can lead to a false positive, making it look like you have a thyroid issue when you don’t. It’s also possible for excessive biotin to prevent your body from absorbing sufficient amounts of other B vitamins, potentially causing other deficiencies. You should never take more than 2.5 milligrams of vitamin B7 a day.

What Are the Symptoms of Biotin Deficiency?

As long as you eat a balanced diet, it’s rare to require additional biotin or have a deficiency. You can get biotin from egg yolks, avocadoes, nuts (e.g., almonds, peanuts, walnuts, etc.) sweet potatoes, legumes, bananas, cauliflower and other veggies.

Signs of biotin deficiency include the following:

  • Brittle fingernails and toenails
  • Red rashes around the nose, mouth, eyes and other openings
  • Skin infections
  • Conjunctivitis
  • Tingling sensations in extremities
  • Feelings of exhaustion
  • Seizures or hallucinations

You should speak with a healthcare professional right away if you notice these symptoms. Your physician can perform a blood test to check your biotin levels and evaluate other symptoms.

Why Do Some People Need To Take Biotin Supplements?

It’s important to speak with your doctor if you think you may have a deficiency in vitamin B7. Women who are pregnant and breastfeeding have an elevated likelihood of B7 deficiency. At the same time, taking too much of this vitamin can increase the risks of miscarriage slightly.

Certain medications can also lower the body’s levels of biotin, potentially causing a deficiency. Anti-seizure medications and antibiotics can have this effect if you take them for an extended period.

Some babies are born with a rare disorder called biotinidase deficiency, a condition caused by a defective gene. Fortunately, doctors screen newborns in the U.S. for BTD. It’s important to follow the doctor’s instructions when treating babies or children for biotin deficiencies.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By anon1000445 — On Sep 23, 2018

I seem to have had the cystic acne reaction to one hair, skin and nails vitamin( natures truth) but not the gummy form. Maybe it was too high a biotin dose or maybe it was the added iodine. I'm sorry to see I'm not the only one. I have had acne in the past but this is the first time in years that I've had a break out like this. I would suggest trying lower dosage or gummy vitamins instead of liquid gels or liquid.

By anon998499 — On Jun 21, 2017

Please help. My hair has always been my pride and joy. I figured since it is pretty damn healthy, it could deal with some bleach damage. And I figured the master stylist who did all the color-corrections would know how much would be too much. I was wrong, and now I want to burst into tears every time I look at my hair or touch it. I just don't know what to do. my hair has also NEVER been shorter than this and it breaks and falls out. What should i do to regrow hair?

By johnlove — On May 17, 2015

I took 2,000 mcg of biotin daily. It stopped my hair loss in less than a week. But it is bad for my penis, and I hope the ED (erectile dysfunction) is temporary.

By anon951899 — On May 18, 2014

I had acne exactly like this for years. It turns out it was the result of a fluoride allergy, caused by toothpaste, and is apparently very common. If you're suffering from a skin condition like this, seriously try buying some fluoride-free toothpaste and wait a month or so. I honestly believe it will work!

By anon943474 — On Apr 01, 2014

Does biotin cause sleeplessness?

By anon341194 — On Jul 09, 2013

I've been taking Biotin for about a week and there's been tightness in my chest when I sneeze or cough. I recently woke up with a sore throat. Because nothing else in my lifestyle has changed, I'm pretty confident biotin is causing this.

By anon337962 — On Jun 09, 2013

I have been taking biotin for about three weeks now and I don't have any side effects. I have gained 4kg in that time but I don't know if that is down to biotin. Does anyone know if it makes you gain weight?

By Mor — On Feb 16, 2013

@croydon - Something people might need to keep in mind if they are taking vitamin supplements AND drinking those energy drinks. That might be why they are getting too much biotin.

I don't really see the point in taking so much biotin that you'll be getting biotin overdose side effects. It's not going to help you more the more you get of it, it's only going to make you feel better if you haven't been getting enough.

B vitamins are water soluble as it says in the article, so it's a good idea to have them regularly, since they don't stay in your body. But taking huge amounts at a time doesn't work. It's better to have a little bit, regularly.

By croydon — On Feb 15, 2013

@SarahGen - I doubt it. If anything it would have the opposite effect, since having a vitamin B deficiency is usually associated with being tired. That's why a lot of energy drinks and also those effervescent tablet drinks are supplying you with various vitamin B types including biotin.

So, if you've got a deficiency you might be feeling quite tired and often people will eat more and not get enough exercise when they feel like that. Taking supplements can help.

By discographer — On Feb 15, 2013

@anon260400-- I know! Me too! It also took me a while to figure out that my acne is one of biotin supplement side effects.

Have you tried lowering your dose? Right now I'm taking 30mcg and I don't have acne. You might want to do that if you don't want to quit completely.

By stoneMason — On Feb 15, 2013

I think I'm allergic to biotin. Either that or I accidentally overdosed on it.

I took it once three months ago, and the next day, I woke up with a terrible rash. I also vomited twice that day. I have never taken it again.

I have a cousin though who takes it regularly without any side effects. I guess it's just me.

By SarahGen — On Feb 14, 2013

Do biotin vitamin supplements cause weight gain?

By anon260400 — On Apr 10, 2012

This information is incredibly helpful. I have been taking high doses of hair, skin and nail vitamins for four years. My hair and nails are beautiful, but my skin has been horrible. I have been on three acne medications for years. I have tried three different methods of birth control.

I ran out of my hair, skin and nails pills for three months and my skin was perfect. I started taking the vitamins again six weeks ago. For the last four weeks, my skin has been terrible. I wish I had found this information years ago. I would have saved myself a ton of anguish, time, and money.

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