Biotin (vitamin B7, vitamin H) is one of the most popular nutraceuticals on the market. It is purchased over the counter and taken for months or even years: the beauty industry has long established a firm association between this vitamin and improved skin, hair, and nail condition. There is a biological rationale for this positioning — biotin is a cofactor for five carboxylases involved in fatty acid synthesis and amino acid metabolism, and skin appendages are among the first to suffer when it is deficient [1]. The historical name "vitamin H" derives from the German words Haut (skin) and Haar (hair), and this association has driven its widespread use in cosmetic products, pharmaceuticals, dietary supplements, and fortified foods. The problem lies elsewhere: the immunological risks of high-dose biotin are largely unknown to patients and, to a significant extent, to medical professionals.

Biotin sources and imbalance

Biotin reaches the body through food and is synthesized by gut bacteria — humans do not produce it endogenously [1]. The richest dietary sources include liver, egg yolk, peanuts, yeast, sunflower seeds, and salmon. With a balanced, varied diet, an adult obtains 30–70 mcg of biotin per day, fully meeting the daily requirement — meaning that deficiency does not develop under normal eating patterns [1]. When it does occur — during prolonged parenteral nutrition, anticonvulsant therapy, Crohn's disease, or regular consumption of large quantities of raw egg whites (whose avidin specifically blocks biotin absorption) — symptoms primarily affect the skin, hair, and nails. The opposite extreme — excessive biotin intake through supplements — is equally non-neutral: both deficiency and excess can disrupt immune homeostasis [1].

About this study

In 2025, Nutrients (MDPI) published a review by Polish allergologist Kinga Lis from the Ludwik Rydygier Collegium Medicum of Nicolaus Copernicus University in Torun [1]. The work provides a systematic analysis of biotin's role in allergic reactions across three dimensions: as a direct causative factor (allergen or hapten), as a condition predisposing to environmental allergen sensitization through immune homeostasis disruption, and as a significant interfering factor in immunochemical allergy diagnostics — primarily in the determination of total and specific immunoglobulin E (tIgE and sIgE).

Biotin and the immune system: where the risks arise

Biotin regulates the expression of transcription factors NF-κB and Sp1/3 and modulates the production of a range of cytokines — interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukins (IL) -17, -12, -4, -2, and -1β [1]. This means that both deficiency and excess of the vitamin can destabilize the balance between pro- and anti-inflammatory processes. In a mouse model, biotin-deficient animals developed contact hypersensitivity to nickel significantly more often—driven by excessive production of the pro-inflammatory IL-1β; biotin administration reduced the reaction in a dose-dependent manner [2]. In an observational study of 411 Japanese schoolchildren aged 6–12 years, a positive correlation was found between serum biotin levels and concentrations of tIgE, as well as sIgE to cedar pollen, cat, and egg white allergens; children sensitized to cedar pollen had significantly higher mean biotin levels than those with other forms of allergy [3].

Regarding direct hypersensitivity to biotin, only two cases have been documented in the global literature — and both are exclusively associated with occupational exposure, not supplement use or cosmetics. In 1942, a pharmaceutical worker was diagnosed with contact hypersensitivity to biotin: a patch test elicited a pronounced reaction—diffuse erythema, edema, and blister formation, with persistent tenderness 36 hours later [1]. In 1998, a 45-year-old man who had worked for 1.5 years in the production of biotin precursors developed pruritic eruptions on his face and hands, eosinophilia, and an extremely elevated IgE level of 1,000 kU/L; symptoms resolved completely after changing jobs [1].

A separate and clinically most significant aspect of the work is biotin's ability to distort immunochemical test results. Many analytical platforms for tIgE and sIgE determination use the biotin–streptavidin system as a core functional component. High biotin concentrations in a patient's blood sample competitively block or over-saturate streptavidin reagents, leading to false-negative or false-positive results depending on the assay format [4]. Scheib et al. demonstrated that this effect can produce false-negative sIgE values in patients with anaphylaxis — a scenario in which a life-threatening allergy goes undetected [5]. Systems known to be susceptible to this type of interference include 3GAllergy IMMULITE-2000 (Siemens Healthcare Diagnostics) and NOVEOS (HYCOR Biomedical). The widely used ImmunoCAP platform (Thermo Fisher Scientific/Phadia AB) does not employ biotin–streptavidin chemistry and is not affected by this type of interference [1].

Study limitations

The author acknowledges the limitations of the work: most data on biotin's effects on the immune response derive from experimental models or isolated clinical observations; causal relationships between biotin levels and allergic sensitization in humans remain unestablished; and the molecular mechanisms underlying the identified correlations require further investigation [1].

Practical takeaways

Several actionable conclusions emerge from this work for the practicing specialist.

• Before blood collection for immunochemical testing, including tIgE and sIgE determination, patients should discontinue biotin; standard doses require a 48-hour washout, and high doses (100–300 mg/day) require at least 3 days [1].
• Information about biotin-containing supplement use must be noted on the test requisition and communicated to the laboratory.
• When discontinuation cannot be guaranteed, analytical systems that do not use biotin–streptavidin chemistry should be preferred.
• In cases of occupational exposure to B-group vitamins or their production precursors, biotin should be considered a possible etiological factor in dermatitis of unclear origin, with patch testing using the native substance.

Biotin has long moved beyond the realm of nutrition science and become part of the everyday practice of skincare specialists, dermatologists, and allergologists — though not always as an ally. The widespread use of high-dose biotin supplements creates a real and underappreciated risk of distorting allergy diagnostic results. Lis's work is a timely, practice-oriented reminder: a "safe vitamin" deserves the same careful medication history intake as any other drug.

References

1. Lis K. Biotin supplementation — the cause of hypersensitivity and significant interference in allergy diagnostics. Nutrients 2025; 17(14): 2423.
2. Kuroishi T., Kinbara M., Sato N. et al. Biotin status affects nickel allergy by regulating interleukin-1β production in mice. J Nutr 2009; 139(6): 1031–1036.
3. Sakurai-Yageta M., Mashimo Y., Kuroishi T. et al. Association between serum biotin levels and cedar pollinosis in Japanese schoolchildren. J Nutr Sci Vitaminol 2021; 67(4): 211–216.
4. Balzer A.H.A., Whitehurst C.B. An analysis of the biotin-(strept)avidin system in immunoassays: interference and mitigation strategies. Curr Issues Mol Biol 2023; 45(11): 8733–8754.
5. Scheib N., Bauersachs D., Pogorelov D. et al. Biotin interference can cause false-negative specific IgE results in patients with anaphylaxis. J Allergy Clin Immunol Pract 2022; 10(9): 2459–2462.e2.