What To Know About The Side Effects Of Taking Biotin For Your Hair And Nails
If you’ve hung out in your drugstore’s vitamin aisle before, you’ve probably bumped into this cool kid on the block: biotin. Sellers of this beauty supplement make some pretty big promises. People claim it can give you hard-ass nails, hair that’s sleek AF, and flawless skin that could only otherwise be achieved by an Insta filter.
It’s cheap and easy to access over the counter (plus celebs like Kylie Jenner have posted #ads for biotin for hair on IG), so it comes as no surprise that women are popping biotin in droves.
But is this supplement really the godsend it claims to be? And are there any biotin side effects of biotin you should know about? Your guide, ahead.
What is biotin, anyway?
Biotin (a.k.a. vitamin B7 or H) is a B-complex vitamin that's found in many foods, including eggs, milk, nuts, and grains, says Shaemah Khan, DO, diplomate of the American Osteopathic Board of Family Physicians and clinical associate of family medicine at University of Chicago Medicine. “One of the effects of biotin is that it helps turn the carbohydrates, fats, and proteins in the food you eat into the energy you need.”
Because it’s water-soluble (meaning it dissolves in water), excess biotin isn’t stored in your body; it actually just flushes right out of you when you pee. But if you follow a healthy, balanced diet, it’s likely you already get all the biotin you could possibly need, anyway. (More on recommended biotin levels later.)
But wait, is it possible to have a biotin deficiency?
Although it’s uncommon, it is possible to be deficient in biotin, says Rajani Katta, MD, a dermatologist in Houston and author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. There are some genetic conditions that can cause you to have low biotin levels, like biotindase deficiency disorder, and this can lead to hair loss, red flaky rashes on the skin, and brittle nails. Other factors that might lead to lower levels of biotin are smoking, excessive alcohol intake and pregnancy. People who take certain anti-epileptic medications may also develop a biotin deficiency.
You're also more likely to develop a biotin deficiency if you have a condition that impacts your digestive tract, like inflammatory bowel disease or small intestinal bacterial overgrowth. That's because biotin is naturally produced by certain gut bacteria in the intestines, so any condition that throws off the microbes in there can impact the effective production of the vitamin, says Dr. Katta.
Still, "our bodies require only a very small amount of biotin, which is easily achieved if you’re eating a relatively normal American diet,” says Kimbre Zahn, MD, family medicine physician at Indiana University Health.
What are the heath benefits of taking biotin?
Aside from being touted as a magic remedy for thinning hair, brittle nails, and dry, itchy skin, biotin supplements can sometimes be prescribed by doctors for other reasons too, like easing disabilities brought on by multiple sclerosis, alleviating diabetes and diabetes-related nerve damage, or encouraging baby growth and development during pregnancy, according to the National Library of Medicine.
Most of the touted beauty benefits, like stronger nails, are anecdotal though. “There have been a few very small studies indicating that taking biotin can lead to an improvement in brittle nails, but it’s important to note that we do not know these patients’ baseline biotin status, and the studies did not include a placebo group,” says Dr. Katta.
Overall, there's very little evidence that taking biotin can help people in the absence of a deficiency. In other words, if you don't have any signs of being deficient in biotin (which, again, is rare), then taking extra hasn't been proven to have benefits, says Dr. Katta.
Tell me: Does biotin work for hair growth?
Don't get toooo excited. A few studies point to biotin as an effective supplement for hair growth, but the cold, hard truth is that there isn’t much scientific proof to show just how effective it really is at treating any of these health conditions—or whether there are long-term benefits to the dietary supplement.
“While there are some preliminary studies that may suggest a benefit [to taking biotin supplements], overall there is a lack of evidence to support these claims,” says Dr. Zahn.
Dr. Katta also notes that there's no research on how biotin affects women of color's hair and bodies, so there's no saying if it would result in any improvements for natural hair.
“Unless you are deficient, I don't recommend taking extra biotin since there is limited evidence that it results in hair and nail growth,” she says.
How can I get more biotin from my diet?
Dermatologists recommend eating more of these foods if you want to up your biotin intake without taking a supplement.
Egg yolks
Nuts
Seeds
Sweet potatoes
Salmon
Lean meats, or organ meats such as liver
Does biotin have side effects?
Truth is, you’re most likely never going to hear about someone ODing on biotin. It almost never happens. “Side effects from having a high dose or overdose of biotin are rare,” says Dr. Khan. “Because it is so easily excreted in urine and feces, the body can simply get rid of any excess.”
However, hair, skin, and nails supplements do come with one warning: Even in small amounts of biotin, one of the side effects of biotin is that it can sometimes totally screw with your lab test results. This is especially true if you’re testing for issues with your thyroid or hormone levels, cardiac troponin levels (used to diagnose heart attacks), or vitamin D levels. This could lead to bogus results and misdiagnosis, which could potentially be dangerous or lead you to worry or spend money on medical procedures or meds unnecessarily.
“The U.S. Food & Drug Administration (FDA) further warns that the biotin effect on the monitoring of cardiac troponin has resulted in at least one death due to a falsely reported low results,” says Michelle Galant, MD, dermatologist at Stanford Health Care.
If you do take biotin, keep this in mind the next time your doc orders a routine lab test. “It’s best to disclose to your doctor and dietitian which supplements you are taking to avoid misdiagnosing a medical condition,” says Sandra Arévalo, RDN, spokesperson for the Academy of Nutrition and Dietetics and the American Association for Diabetes Educators, and director of nutrition services outreach for the community pediatrics programs at Montefiore Hospital.
There’s no hard evidence that says exactly how long biotin stays in your system after you take it, so your doctor might recommend you stop taking the supplement a few days before you head to the lab.
Other potential biotin side effects? While it's supposed to strengthen hair, skin and nails, it could cause a skin rash if you're taking large amounts of biotin. See your doctor if you develop a rash after taking biotin or increasing your dose. It should resolve itself if you lower the amount of biotin you're taking or stop taking the supplement altogether.
“Some people have also reported digestive upset from extra biotin,” Dr. Katta says. “We also don’t understand exactly how large doses affect insulin function and blood sugar levels in different people, so that’s an area that definitely needs further research.” Again, before you start taking a supp, talk to your doc to make sure it won't interfere with any meds you're taking or any conditions you have.
Should I even bother taking biotin?
Honestly, probs not. Thanks to its lack of scientific backup and its reputation as a lab test saboteur, biotin isn’t generally recommended by most doctors. But if you still want to take it anyway, just make sure you’re buying a reputable brand (look for the "USP verified" on the label), and are aware of the side effects.
In terms of how much biotin you need, the recommended "adequate intake" (AI) level for biotin is up to 30 micrograms (mcg) for women 19 years old and up, says Arévalo. "Pregnant women should consume 30 mcg; 35 if nursing," Arévalo adds.
But remember: If you are eating a healthy diet that includes meats, seeds, nuts, and vegetables, you are most likely reaching this intake already, and the biotin side effects might not be worth it. "If you are skipping certain foods or food groups, it will be good to talk to a registered dietitian to help you find which nutrients you might be deficient in, and whether you need to supplement or just eat more of other foods," says Arévalo.
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