What are the potential side effects of taking biotin tablets as supplements, particularly in patients with a history of kidney or liver disease?

Biotin Tablet Side Effects

Biotin supplementation is remarkably safe with no established upper limit and no adverse effects reported at doses up to 5 mg/day for prolonged periods, though patients with kidney or liver disease require special consideration for laboratory test interference and potential absorption issues. 1

Safety Profile in General Population

Biotin toxicity is unlikely and no upper tolerable limit (UL) has been established by major nutrition societies. 1

• No adverse effects have been documented with either oral or intravenous administration of pharmacological doses up to 5 mg/day for extended periods 1
• High doses up to 300 mg/day have been used extensively in parenteral nutrition for years without toxicity issues 1
• The ESPEN 2022 guidelines provide Grade B recommendations for doses of 30-60 mcg/day in standard nutrition, with strong consensus (95-100%) on safety 1

Critical Laboratory Test Interference

The most significant "side effect" of biotin is not toxicity but dangerous interference with clinical immunoassays that can lead to misdiagnosis and inappropriate treatment. 2, 3

• Biotin levels above recommended daily allowances interfere with laboratory tests using biotin-streptavidin immunoassays, including cardiovascular diagnostic tests (troponin), hormone tests (thyroid function, parathyroid hormone), tumor markers, and pregnancy tests 2, 3, 4
• This interference can be positive or negative depending on the specific assay, potentially masking true disease or creating false diagnoses 3
• Patients must abstain from biotin supplements for 48 hours before laboratory testing to avoid clinically significant interference 3
• Case reports document falsely elevated free T3/T4 with suppressed TSH mimicking hyperthyroidism, leading to inappropriate anti-thyroid medication 5
• In hemodialysis patients, biotin caused spurious 25-hydroxyvitamin D spikes from 25 to >100 ng/mL and iPTH drops from 966 to 63 pg/mL, which could adversely affect bone disease management 4

Special Considerations for Kidney Disease

Patients with chronic kidney disease have compromised biotin absorption and altered status, but supplementation remains safe when properly monitored. 1

• Intestinal absorption of biotin may be compromised in CKD patients 1
• Hemodialysis impact on biotin status is poorly understood, with both high and low blood levels reported in the literature 1
• Patients on renal replacement therapy may require additional biotin amounts beyond standard recommendations 1
• Intake equal to the Dietary Reference Intake (DRI) should be provided through diet and/or supplementation 1
• Historical case series showed marked neurological improvement in 9 hemodialysis patients with encephalopathy and peripheral neuropathy treated with 10 mg biotin daily for 1-4 years, with no adverse effects reported 6

Liver Disease Considerations

The provided evidence does not contain specific information about biotin metabolism or safety in liver disease. However, given biotin's water-soluble nature and the lack of established toxicity at therapeutic doses, standard precautions regarding laboratory test interference apply 1.

Rare Allergic Reactions

• Biotin formulations containing FD&C Yellow No. 5 (tartrazine) may cause allergic-type reactions including bronchial asthma in susceptible patients 2
• This sensitivity is more frequently seen in patients with aspirin hypersensitivity, though overall incidence in the general population is low 2

Potential Neurological Worsening (High-Dose Context)

• In progressive multiple sclerosis patients treated with 300 mg/day biotin, one-third (38-43%) experienced worsening symptoms including increased lower extremity weakness, balance problems, and falls 7
• Some patients improved after discontinuing biotin, suggesting possible inability of injured central nervous systems to respond to increased metabolic demands 7
• This effect appears specific to high-dose therapy (300 mg/day) in neurologically compromised patients, not standard supplementation 7

Clinical Management Algorithm

1. Before prescribing biotin: Screen for aspirin hypersensitivity and tartrazine allergy 2
2. Document biotin use: Ensure all healthcare providers and laboratories are aware of biotin supplementation 2, 3
3. Laboratory testing protocol: Discontinue biotin 48 hours before any immunoassay testing, particularly thyroid function, cardiac markers, or hormone panels 3
4. Kidney disease patients: Monitor for adequate intake (DRI levels), consider increased needs with dialysis, and be vigilant about laboratory interference 1, 4
5. Pregnancy/lactation: Ensure at least 35 mcg/day orally for breastfeeding mothers, with potential increases up to 300 mcg/day in pregnancy based on metabolic markers 1, 8