Why This Popular Supplement May Do More Harm Than Good for Patients With Cancer

For many patients undergoing cancer treatment, hair loss is one of the most distressing adverse effects. In an effort to take proactive control of their health, many turn to over-the-counter hair, skin, and nail vitamins. However, Brittany Dulmage, MD, an oncodermatologist at The Ohio State University Wexner Medical Center, warns that these supplements—specifically those containing biotin—may be ineffective at best and dangerous to clinical monitoring at worst.

The Hidden Danger in the Lab

As an oncodermatologist, Dulmage specializes in managing the adverse effects of chemotherapy and long-term hormonal medications. She noted that patients often start supplements long before they reach her clinic.

“One of the things patients are starting on their own before they ever make it to my clinic is an over-the-counter supplement... and many of those contain biotin,” Dulmage explained. While biotin is marketed as a primary active ingredient for hair growth, the American Academy of Dermatology recently issued a position statement urging caution.

“The evidence for [biotin] as an actual effective treatment for hair loss is very weak,” said Dulmage. “There is very little evidence that biotin does anything to help grow hair.”

Beyond its lack of efficacy, biotin poses a significant risk to a patient’s medical workup. It has the potential to interfere with blood work, particularly tests related to hormone levels. Dulmage clarified that the vitamin doesn't change the body’s actual chemistry, but rather the accuracy of the test itself.

“It’s not that biotin changes the levels of hormones in the patient... but what happens is that biotin can bind in the tube of blood that’s drawn to some of the chemicals that are used to run the test, and that can lead to skewing the results to be falsely high or falsely low.”

For patients with cancer, this interference is critical. Oncologists rely on these labs to assess treatment response, monitor adverse effects, and make vital therapeutic decisions.

A Gap in Awareness

Despite these risks, biotin remains a common recommendation within the oncology community. Dulmage noted that many patients arrive at her office stating they started the supplement because their oncologist said it was "fine to try."

“I think that probably stems from the fact that biotin is a B vitamin,” she said. “Even patients who have more restrictive diets... are still getting plenty of access to biotin. So, I think there's this idea that, well, it's a B vitamin, it's something we need anyway, it's safe. There's low risk. And I don't think many oncologists were aware... of the potential for biotin to interfere with blood work.”

Data from Dulmage’s lab highlighted the scale of this issue. In a study of over 200 patients from online support groups, her team found that adding a vitamin or supplement was the #1 self-prescribed treatment for hair loss. Shockingly, only 6% of those patients actually made it to a dermatologist.¹

Navigating Supplements Safely

When it comes to hair loss, Dulmage’s advice is straightforward:

• Skip the "Hair, Skin, and Nails" Blends: There is generally no evidence to support them.
• Check Iron Levels: “Only if they're deficient do I recommend supplementing iron.”
• Consult a Pharmacist: Clinical pharmacists on oncology teams are invaluable for identifying risks between supplements and prescribed drug regimens.

A Proven Alternative

For patients seeking a safe, evidence-based way to address hair thinning, Dulmage suggests oncologists point their patients toward a common over-the-counter solution.

“Aside from patients who are breastfeeding or pregnant, topical minoxidil is safe for the large majority of patients to try,” she shared. “It’s readily available over the counter... and does not have any interaction with oncology medications or have any additional risk in patients who have an underlying cancer that’s being treated. It’s a safe option that does have many years of data to back it up as an effective choice.”

REFERENCE

1. Mager L, Ueltschi O, Rose L, Dulmage B. Biotin Supplements for Hair and Nail Regrowth: A Caution for Oncologists. JCO Oncol Pract. 2025 Sep 15:OP2500693. doi: 10.1200/OP-25-00693. Epub ahead of print. PMID: 40953333.