logoThe People's Perspective on Medicine

Beware of Biotin Interfering With Thyroid Tests

Doctors and patients should beware of biotin supplements messing up thyroid test results. To avoid a false diagnosis, a person should stop the biotin first.
Winneconne, WI – 27 May 2019 : A collection of biotin supplements on an isolated background

It’s alarming to get a laboratory test result that shows a serious problem. Learning later that the test might have given a false reading is also frustrating. One reader discovered that you should beware of biotin if you are having thyroid tests run.

Why Should You Beware of Biotin?

Q. My husband recently had blood tests that showed he was hyperthyroid. His doctor ordered further tests, including a thyroid scan and an iodine uptake test.

Then an endocrinologist mentioned that the thyroid blood tests can be affected by biotin. We checked our multi-vitamin, and there were 500 mcg of biotin! Normal RDA is 30 mcg. Others should be warned about this.

Biotin Can Interfere With Tests for TSH:

A. The usual test for thyroid-stimulating hormone (TSH) is subject to interference when biotin levels are high (Nutrition, Jan. 2019).  The result is that TSH appears lower than it actually is, leading to a false diagnosis of hyperthyroidism. When TSH is low, that is an indication that the pituitary gland in the brain is trying to shut down thyroid hormone production. Normally, that would be due to excess thyroid hormone in circulation. But biotin from B vitamins or other products can grab TSH and lower it artificially.

Doctors and patients should both beware of biotin giving a false result on thyroid tests. Patients might be wise not to take biotin-containing products, such as vitamins or hair-restoration products, when they are being tested for thyroid problems.

Learn More:

Biotin is not the only thing that can interfere with blood tests for thyroid function. You can find out about others in our eGuide to Thyroid Hormones.

Rate this article
4.2- 130 ratings
About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
Tired of the ads on our website?

Now you can browse our website completely ad-free for just $5 / month. Stay up to date on breaking health news and support our work without the distraction of advertisements.

Browse our website ad-free
  • Charles S et al, "Erroneous thyroid diagnosis due to over-the-counter biotin." Nutrition, Jan. 2019. DOI: 10.1016/j.nut.2018.05.005
Join over 150,000 Subscribers at The People's Pharmacy

We're empowering you to make wise decisions about your own health, by providing you with essential health information about both medical and alternative treatment options.

comments (22 total)
Add your comment

I went through two 96 hours rounds of chemotherapy (5-Fu) and 34 radiation treatments for colon cancer. My last round of chemo was the week of Thanksgiving, 2019, and my last radiation treatment was on December 23, 2019. My hair is still thinning (did not lose my hair but it is very thin at this point), and so I started taking biotin (2,000 mcg) daily about 10 days ago. I have taken Synthroid (0.112mg) for 15 years.

My research on hair loss/thinning as a result of chemotherapy and radiation mentioned that cancer treatments can lower the thyroid’s ability to function correctly and since the thyroid can affect hair growth I am wondering if there is a connection? Will taking biotin counteract the effectiveness of the Synthroid I am taking?

So far as we know, it should not affect the Synthroid activity. It will, however, probably alter the test your doctor uses to monitor your thyroid.

About six months ago I started Biotin. The first night my heart beat woke me up. I do have a thyroid problem. I did not put two and two together until the next night when it happened again. It reminded me of when I had hyper-thyroid, and my heart beat the same way. I immediately stopped the Biotin, and the problem stopped.

Yesterday, February 10, 2020, I was informed by my doctor that I should take my over-the-counter supplements five hours AFTER I take my thyroid medication.

I used to take Biotin for better hair and nails. Nothing changed there. However, I started having skipped heart beats. When I stopped the Biotin the skipping stopped.

How long should you stop taking biotin before a thyroid test?

In an article on WebMD — which cites an FDA warning from 11/29/2017 about biotin interference with lab tests — an endocrinologist and medical professor from University of Minnesota says she tells her patients to discontinue supplements one week before lab tests.

Would love to know the publication date of the Thyroid E-Guide. Thanks

Last updated Nov. 2019.

What about Biotin shampoo? I’ve been using Biotin shampoo for years. It has a lot of ingredients besides Biotin, however.

Huh. The only biotin I found in our house is in the shampoo.

I was taking Biotin, and it falsely affected my blood test to show I was hypothyroid. I stopped taking the Biotin, and my hair came in thicker and faster. It is my personal theory that taking Biotin for too long (4 years for me) makes your hair “lazy.” It’s like it says to itself “Why work so hard to grow when you are being given a boost?” I wonder if anyone else has had this experience?

When should you stop the biotin? How many weeks before you get your labs done?

* Be nice, and don't over share. View comment policy^