Nobody mentioned biotin could interfere with your treatment or testing
In the quiet aftermath of cancer treatment, many survivors reach for biotin supplements to reclaim the hair chemotherapy took from them — an understandable act of self-restoration. Yet this common vitamin, abundant in ordinary food and rarely deficient in the body, carries a hidden consequence: it can distort the very blood tests designed to detect whether cancer has returned. Oncologists are now calling for open conversations about this risk, recognizing that the desire to heal one's appearance must not come at the cost of one's ability to monitor one's survival.
- More than half of cancer patients taking biotin for hair loss began without medical guidance, unaware that the supplement could corrupt the lab results their lives may depend on.
- Biotin doesn't alter hormone levels in the body — but it chemically disrupts how labs measure them, potentially hiding cancer recurrence or pushing doctors toward wrong treatment decisions.
- The interference extends beyond cancer markers: biotin can also distort troponin readings used to detect heart attacks, a risk that cannot be managed by simply pausing a supplement in advance.
- Oncologists are urging patients to stop biotin at least 72 hours before scheduled blood work and to consider FDA-approved minoxidil as a safer, clinically effective alternative for hair regrowth.
- The gap between what patients find online and what their care teams communicate remains the central danger — a silence that one patient only discovered after her lab results stopped making sense.
Anna Malagoli finished breast cancer treatment and, like many survivors, wanted to reclaim her identity — specifically, the long curly hair chemotherapy had taken. She found biotin online, read the testimonials, and started taking it in large amounts. No one told her it might interfere with the blood tests monitoring whether her cancer had returned.
Biotin, or vitamin B7, is widely marketed for hair and nail health. It does support keratin production, but true deficiency is rare — most people get enough from everyday food. What concerns oncodermatologist Brittany Dulmage at Ohio State's cancer center is what happens when patients take high-dose supplements hoping to restore their appearance. Biotin doesn't change hormone levels in the body, but it disrupts the chemical reactions labs use to measure them. For markers like PSA and TSH, it can falsely lower readings, potentially masking cancer recurrence. For reproductive hormones, it can falsely elevate them, leading doctors to make decisions based on numbers that aren't real.
Malagoli's own lab results grew inconsistent and confusing — misaligned with how she actually felt. It wasn't until a follow-up with Dulmage that the likely cause emerged. The biotin she had been taking in significant quantities was probably distorting her tests. No one in her care had ever raised the possibility.
Dulmage has published research urging oncologists to discuss hair loss openly with patients and to explain biotin's risks before patients discover supplements on their own. The stakes extend beyond cancer monitoring: biotin can also interfere with troponin levels, a cardiac marker — and unlike scheduled blood draws, heart attacks cannot be anticipated with a 72-hour supplement pause.
For those determined to use biotin, Dulmage recommends stopping it at least three days before any planned blood work. But the safer path, she argues, is minoxidil — an FDA-approved topical treatment with proven efficacy and none of biotin's testing interference. Malagoli tried both and found minoxidil more effective. She now tells other patients what she wishes someone had told her: that the promise of a simple supplement can carry a hidden cost — the risk of missing the very thing you're most afraid of.
Anna Malagoli finished her breast cancer treatment and watched her hair begin to grow back. Like many patients emerging from chemotherapy, she wanted to restore what the drugs had taken—in her case, the long curly hair that had been part of her identity. She found biotin online, read the testimonials, and started taking it. She took a lot of it. Nobody told her it might interfere with the blood tests that would monitor whether her cancer stayed gone.
Biotin, also called vitamin B7, is everywhere in health food stores and online supplement catalogs, marketed as a cure for weak hair and nails. The vitamin does help the body produce keratin, the protein that builds hair and skin. But actual biotin deficiency is rare—the vitamin is abundant in fruits, vegetables, eggs, meat, and dairy. Most people get enough from food alone. What matters more, according to Brittany Dulmage, an oncodermatologist at Ohio State's comprehensive cancer center, is what happens when cancer patients take biotin supplements in hopes of restoring their appearance. The supplements can distort the very blood tests designed to catch cancer's return.
Dulmage has seen this pattern repeatedly in her clinic. More than half the patients who come to her with hair loss problems are already taking supplements they started on their own—found online, recommended by friends, sometimes even suggested by other doctors. None of them understood the risk. Biotin interferes with certain blood tests used to monitor breast, prostate, thyroid, and ovarian cancers. The vitamin doesn't actually change hormone levels in the body, but it disrupts the chemical reactions used to measure those levels in the lab. For markers like PSA (prostate-specific antigen) and TSH (thyroid-stimulating hormone), biotin can falsely lower the readings, potentially hiding cancer recurrence. For reproductive hormones like estrogen and testosterone, it can falsely elevate them, pushing doctors to delay or change treatment based on numbers that aren't real.
Malagoli's experience illustrates the problem. During a follow-up visit with Dulmage, she mentioned that her lab results weren't making sense. They were inconsistent, didn't align with how she felt, raised red flags. Looking back, she realized the biotin was likely the culprit. She had been taking so much of it that the interference was probably significant. No one in her medical care had mentioned that supplements could affect her testing or treatment. The disconnect between her lab numbers and her actual health had gone unaddressed until she happened to see a specialist who knew to ask.
Dulmage has published research in JCO Oncology Practice calling on oncologists to talk openly with patients about hair loss and to explain how biotin could compromise their monitoring. The stakes are high. Biotin can also interfere with troponin levels, a marker of heart attack—and patients can't exactly plan to stop taking biotin before an unplanned cardiac event. For patients determined to use biotin despite the risks, Dulmage recommends stopping it at least 72 hours before any scheduled blood work. But that assumes the blood work is planned. It assumes patients remember. It assumes they know to ask.
The safer alternative is minoxidil, an FDA-approved topical treatment available over the counter in lotions and foams. It's been shown to work for hair regrowth and carries none of biotin's testing interference. Malagoli tried both approaches and found minoxidil more effective for her. She now emphasizes to other patients the importance of listening to doctors rather than following what feels right based on internet research. For cancer survivors already anxious about recurrence, already navigating a complex medical landscape, the promise of a simple supplement that might restore their appearance is seductive. But that promise comes with a hidden cost: the risk of missing the very thing they're most afraid of.
Citas Notables
The supplements may cause inaccurate lab results, resulting in a delay or change in patients' treatment plans— Dr. Brittany Dulmage, oncodermatologist at Ohio State University Comprehensive Cancer Center
My lab results were inconsistent. They just didn't balance out with what I was feeling so that was a red flag— Anna Malagoli, cancer patient
La Conversación del Hearth Otra perspectiva de la historia
Why would cancer patients specifically reach for biotin when there's no real evidence it helps with chemo-related hair loss?
Because hair loss is traumatic. It's visible, constant, a daily reminder of what the cancer took. Patients are desperate to reclaim something normal about themselves, and biotin is cheap, available, and sounds scientific. The internet is full of testimonials. Nobody's telling them it's a trap.
But the real danger isn't that biotin doesn't work—it's that it breaks the tests that catch cancer coming back.
Exactly. It's not just ineffective; it's actively dangerous. The supplement doesn't change what's actually happening in the body, but it changes what the blood tests can see. A cancer marker that should be high reads low. A hormone that should be normal reads elevated. The doctor sees numbers that don't match reality and makes decisions based on a lie.
How many patients are taking biotin without knowing this?
More than half of the ones in Dulmage's clinic. And she's a specialist—she's seeing the people who made it to a dermatologist. The ones who never get that far are just taking it and hoping, never knowing their lab results might be compromised.
Can you just stop taking it before a blood test?
That's what doctors recommend—72 hours before. But what if you have an emergency? What if you're having chest pain and they need to check your troponin levels to rule out a heart attack? You can't plan for that. You can't hold your biotin.
So the real message is: don't take it at all.
Yes. Unless you're actually biotin deficient, which almost nobody is. Minoxidil works better anyway, it's FDA-approved, and it doesn't hide cancer recurrence. But patients have to hear that from their doctors, and they have to trust it more than what they read online.
What does it feel like to be Malagoli, realizing your supplements might have masked something serious?
Terrifying. And angry. She did what seemed reasonable—took a supplement to feel more like herself. Nobody warned her. Her lab results didn't make sense, and she had to piece it together herself with a specialist. That's a failure of communication, not just a supplement problem.