There Are Some Under-the-Radar Side Effects of Biotin We Need to Tell You About

Biotin is one of the most well-known B complex vitamins, with a reputation as a magical ingredient for healthy hair, skin, and nails. What's more, the vitamin is found in everything from gummy supplements and oral tablets to ingestible powders, making it easy to get a daily dose.

But there are a few sneaky side effects of biotin that most people don't know about. Before multi-ingredient hair growth supplements became the norm, straight-up biotin was one of the only options for growing healthier hair and nails.

While the popular B vitamin is a key ingredient in countless over-the-counter supplements, it can cause side effects for some unlucky people—leading to breakouts, rashes, and more. We tapped dermatologists to get the truth about biotin's benefits and side effects. Here's everything to know about taking biotin supplements—some of what we share may be surprising.

What is biotin?

Besides enhancing the hair, skin, and nails, biotin, also known as vitamin H or vitamin B-7, has several other bodily functions, like aiding in metabolic processes. Dendy Engelman, M.D., a board-certified cosmetic dermatologist, says biotin is a crucial component of keratin production, a protein that strengthens hair and nails. But its primary function is to metabolize amino acids, glucose, and fatty acids in the body to create energy. In other words, it converts the foods we eat into fuel the body can use.

Like any supplement or vitamin, biotin isn't without its risks, and taking too much of it can do more harm than good. Doctors call much of the purported beauty benefits of biotin anecdotal and not scientifically substantiated. "However, people who are truly deficient in biotin can strengthen their thinning hair and brittle nails with biotin," says board-certified dermatologist Marisa Garshick, M.D. The caveat is that most of us are not deficient in biotin. "Still, people find biotin helpful even without being deficient, making it a popular choice for hair loss."

Of course, if your doctor determines that biotin is the root cause of skin, nail, and hair issues, it's best to follow a biotin-rich diet consisting of egg yolks, mushrooms, leafy green vegetables, nuts, cheese, bananas, and chicken. "Eating a balanced diet may be enough to meet your daily biotin requirements—30 to 100 micrograms for most adults," says Dr. Engelman. "I recommend patients obtain biotin through a healthy, balanced diet rather than supplements," Dr. Engelman says.

But diet doesn't always cut it, and that’s where supplements can help. The problem with some biotin-rich hair, skin, and nail supplements is that, according to Nadia Mussavir, N.D., a licensed naturopathic doctor who focuses on a holistic approach to hair and skin concerns, most are dosed at about 650 times the recommended amount of biotin. "There are insane amounts of biotin in products purely because of the hype around it." She says, "Nutrition is just one piece of the hair health puzzle, and biotin is an even smaller piece. Complete amino acids and protein are equally as important for healthy hair."

Biotin Side Effects

Biotin has anti-inflammatory properties and helps to nourish the skin and alleviate dryness. But it can also work the other way and instigate acne, especially when starting on a supplement. While not everyone who consumes an oral supplement with biotin will experience breakouts, plenty do. Dr. Garshick cautions, “Be mindful in case you notice an increase in acne after starting a biotin supplement as it may be somewhat related.“

Unbeknownst to many, biotin itself doesn't directly cause acne. Dr. Garshick explains that the amount of biotin in the gut may be relatively higher than other B vitamins, specifically vitamin B5 (pantothenic acid). “This can lead to a relative decrease in vitamin B5, which is thought to help prevent breakouts.” While pimples can happen to anyone taking biotin, she adds that those susceptible to acne may be more prone to breakouts. “Further research is needed to understand the association of acne and biotin better."

If you notice an uptick in pimples while taking a biotin supplement, the easiest way to stop the cycle of breakouts is to cut down on or cut out the supplement. An anti-acne skincare routine consisting of retinoids, benzoyl peroxide, or salicylic acid, known acne-fighting ingredients, can also improve the skin. The upside is that biotin is a water-soluble vitamin, so it's released from the body (via urine) relatively soon. "It's hard to say how quickly you'll see an improvement in the skin once you stop taking biotin because there may be other factors that play a direct role in the formation of acne, too," Dr. Mussavir says.

It's not just acne that has some biotin users swearing off the supplement. Skin rashes can also occur, which Dr. Engelman calls "a more common side effect of biotin." She says most biotin-related skin rashes are due to taking too much biotin. "Some products contain high levels of it that are too high, which is why it's essential to read the label," she explains. Taking more biotin than necessary to try and grow thicker hair fast isn't the solution. 

"If you're especially sensitive to the ingredient, you may have an allergy that manifests as a skin rash," Dr. Engelman shares. Sometimes, scaling back on the dose is all that is needed to clear up the skin. But for others, it may require quitting the supplement altogether. 

Will biotin affect blood tests?

Here's one thing to note if you take biotin supplements daily: they can interfere with immunoassay blood tests, which test the levels of different substances in the body. “This occurs when biotin is used as part of the test,” Dr. Engelman says. “This is common with immunoassay tests for hormones, but it may interfere with others as well.” 

High levels of biotin can cause blood and lab tests to read as false negatives or false positives. So if you know you'll have lab work done, it's best to stop taking biotin supplements or any containing it about one week before the test to ensure everything will read clean.

The Takeaway

Simply put, taking biotin is safe as long as you're not overdoing it.

If biotin supplements have you second guessing their benefits, or they’re leading to some unwanted side effects, look for supplements with lower doses of biotin. Dr. Mussavir purposely incorporated a lower amount of biotin—600 mcg—which she says is far less than most other supplements. “High levels of biotin aren’t necessary.”

Gummies are another option, although Dr. Garshick says they’re generally considered less bioavailable than tablets. “ There are also powders that incorporate lower doses of biotin, along with other hair and skin helpers like collagen, vitamins, hyaluronic acid, and zinc.

Dr. Mussavir recommends looking for a complete hair, skin, and nail supplement that includes other necessary vitamins, proteins, fatty acids, minerals, and ingredients that support and impact the hair growth cycle. "Biotin alone is not the end-all solution for most hair concerns," Dr. Mussavir declares.