✓ No active regulatory warningsFDA MedWatch, EMA EudraVigilance, WHO VigiBase, WADA Prohibited List · 2026-05-29
📰Read the full Thiamine evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ Confusion, ataxia, or ophthalmoplegia in any malnourished or alcoholic patient — treat as Wernicke encephalopathy (IV thiamine 200–500 mg TID) without waiting for labs [2]
⚠ Heart failure patients on furosemide — thiamine depletion occurs in up to 33%; consider empiric supplementation [6]
⚠ Post-bariatric surgery patients with neurological symptoms — test and treat promptly [3]
⚠ Hyperemesis gravidarum with confusion — Wernicke encephalopathy in pregnancy is underdiagnosed [2]
🥗 Food first — build your daily 1.2 mg/ 1.1 mg
Check the foods you regularly eat — the bar fills toward your daily target.
Pork chop (85g)0.8 mg
Enriched rice (1 cup)0.3 mg
Black beans (½ cup)0.2 mg
Trout (85g)0.4 mg
Sunflower seeds (28g)0.4 mg
Green peas (½ cup)0.2 mg
Check your regular foods above
☑ Risk checker
Chronic alcohol use disorder — the most common cause in developed countries [2]
Polished rice-dependent diets without fortification [3]
Prolonged vomiting (hyperemesis gravidarum, cyclic vomiting) [2]
Heart failure with chronic loop diuretic therapy [6]
Bariatric surgery (especially gastric bypass) [3]
HIV/AIDS and chronic infections [3]
Elderly in institutional care with poor dietary intake [3]
Refeeding after prolonged fasting or starvation [2]
Select factors
🔬 Lab interpreter
Recommended test
Whole blood thiamine (or erythrocyte TPP)
Whole blood thiamine (or erythrocyte TPP)
Reference range / target
70–180 nmol/L (whole blood)
70–180 nmol/L (whole blood)
More reliable than serum thiamine, which fluctuates with recent intake. Erythrocyte TPP reflects tissue stores over the preceding 120 days [2].
Full lab monitoring ↓⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: Specific dosage data under clinical review
👦 Pediatric: See guidance
Infants 0–6 months: 0.2 mg/day AI; 7–12 months: 0.3 mg/day. Children 1–3 years: 0.5 mg/day; 4–8 years: 0.6 mg/day [1]. Infantile beriberi in breastfed infants of deficient mothers presents wit
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: Can be taken any time of day, with or without food. Thiamine is water-soluble and does not require fat for absorption [1].
💊 With food: No specific food pairing required. However, tea and coffee contain thiamine-degrading compounds (polyphenols); avoid consuming within 1 hour of supplementation at high doses [3].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['Thiamine HCl', 'common', 'Most widely available supplemental form. Water-soluble. Absorbed via active transport in the duodenum and jejunum at doses up to ~5 mg; passive diffusion at higher doses [1].'] | Standard | Check label | |
| ['Thiamine mononitrate', 'common', 'Used in food fortification due to greater stability. Equivalent efficacy to HCl form. Found in enriched flour and cereal products [1].'] | Standard | Check label | |
| ['Benfotiamine', 'preferred', 'Lipid-soluble prodrug with 5-fold greater bioavailability than thiamine HCl [4]. Reaches higher intracellular concentrations. Studied for diabetic neuropathy and advanced glycation end-product inhibition [4].'] | Standard | Check label | |
| ['Sulbutiamine', '', 'Synthetic dimer of thiamine. Crosses blood-brain barrier more readily than thiamine HCl. Used in some countries for asthenia. Limited clinical trial evidence [3].'] | Standard | Check label |
3 Common questions
How quickly does thiamine deficiency develop? ▼
The body stores only 25–30 mg of thiamine, with a half-life of 9–18 days. With zero intake, clinical deficiency can develop within 2–3 weeks [3]. Patients with increased metabolic demands (alcoholism, heart failure, infection) may develop deficiency even faster.
Why is thiamine given before glucose in emergency settings? ▼
Glucose administration in a thiamine-depleted patient increases metabolic demand for thiamine (as a cofactor for pyruvate dehydrogenase) and can precipitate or worsen Wernicke encephalopathy [2]. The standard of care is to administer IV thiamine before or simultaneously with glucose in any malnourished or alcoholic patient.
Does alcohol destroy thiamine? ▼
Alcohol impairs thiamine through multiple mechanisms: reduced dietary intake, decreased intestinal absorption, impaired hepatic storage, increased renal excretion, and inhibited phosphorylation to the active TPP form [2]. Chronic alcohol use is the leading cause of thiamine deficiency in developed countries.
Is benfotiamine better than regular thiamine? ▼
Benfotiamine is a lipid-soluble prodrug with approximately 5-fold greater bioavailability than thiamine HCl [4]. It reaches higher intracellular concentrations and has shown benefit for diabetic neuropathy. However, it does not cross the blood-brain barrier as effectively as IV thiamine, so it is not a substitute for IV treatment of Wernicke encephalopathy [4].
4 Clinical evidence
Strong
Treatment and prevention of beriberi (dry beriberi: peripheral neuropathy; wet beriberi: cardiac failure) [3]. Treatment of Wernicke encephalopathy: high-dose IV thiamine (200–500 mg three times daily) is the standard of care and should be administered before glucose in any suspected case [2]. Prevention of Wernicke-Korsakoff syndrome in chronic alcoholism with thiamine supplementation [2]. HIGH
Moderate
Benfotiamine at 300–600 mg/day improved neuropathic symptoms in diabetic patients in the BENDIP trial (n = 165) [4]. Thiamine supplementation (200 mg/day) reduced lactate levels and improved cardiac function in patients with heart failure in a small trial (n = 33) [6]. High-dose thiamine may reduce hyperglycemia-induced vascular damage through transketolase activation [4]. MODERATE
Insufficient
5 Safety, toxicity & adverse events
Relative
⚠ Known hypersensitivity to thiamine (rare but reported with IV administration)
🚩 Red flags
● Acute confusion + ataxia + eye movement abnormalities — Wernicke encephalopathy. Give IV thiamine 200–500 mg TID immediately [2]
● Unexplained high-output heart failure (wet beriberi) — check thiamine status and supplement [3]
● Post-bariatric surgery patient with new peripheral neuropathy — urgent thiamine assessment [3]
● Hyperemesis gravidarum requiring IV glucose — administer thiamine BEFORE glucose [2]
● Refeeding syndrome in a malnourished patient — thiamine must be replenished before caloric loading [2]
6 Interactions
Drug interactions
Loop diuretics (furosemide, bumetanide) Major
Mechanism: Loop diuretics increase renal clearance of thiamine by up to 6-fold through increased tubular flow and impaired reabsorption. [6]
Effect: Biochemical thiamine deficiency in up to 33% of heart failure patients on chronic furosemide. May worsen cardiac function. [6]
Action: Consider empiric thiamine supplementation (100–200 mg/day) in all patients on chronic loop diuretics [6].
5-Fluorouracil (5-FU) Moderate
Mechanism: 5-FU inhibits thiamine phosphorylation to TPP and may contribute to 5-FU-related neurotoxicity. [3]
Effect: Exacerbated neurotoxicity: peripheral neuropathy, encephalopathy. [3]
Action: Monitor neurological status. Consider empiric thiamine supplementation during 5-FU chemotherapy [3].
Phenytoin Moderate
Mechanism: Chronic phenytoin use may deplete B vitamins including thiamine through hepatic enzyme induction. [3]
Effect: Subclinical thiamine depletion contributing to neurological symptoms. [3]
Action: Include thiamine in B-complex supplementation for patients on chronic anticonvulsants [3].
Proton pump inhibitors (chronic use) Minor
Mechanism: Elevated gastric pH may reduce thiamine absorption, which is optimized at low pH. [3]
Effect: Subclinical impact; clinically significant mainly in patients with marginal intake. [3]
Action: Ensure adequate dietary thiamine intake during chronic PPI therapy [3].
Supplement synergies
Magnesium · 320–420 mg/day
Magnesium is a required cofactor for thiamine pyrophosphokinase (converts thiamine to active TPP). Magnesium deficiency renders thiamine supplementation partially ineffective [1].
Magnesium is a required cofactor for thiamine pyrophosphokinase (converts thiamine to active TPP). Magnesium deficiency renders thiamine supplementation partially ineffective [1].
B-complex (B2, B6, B12) · Standard B-complex dosing
B vitamins work as a metabolic team in energy metabolism. Deficiencies often co-occur, particularly in alcoholism and malabsorption [1].
B vitamins work as a metabolic team in energy metabolism. Deficiencies often co-occur, particularly in alcoholism and malabsorption [1].
Vitamin C · 200–500 mg/day
Antioxidant protection of thiamine from degradation. May enhance thiamine utilization in metabolic pathways [1].
Antioxidant protection of thiamine from degradation. May enhance thiamine utilization in metabolic pathways [1].
7 Regulatory
United States (FDA): Classified as a dietary supplement. Mandatory fortification of enriched flour, bread, and cereal grain products since 1941. No UL established [1].
European Union (EFSA): Authorized health claims for energy-yielding metabolism, nervous system function, cardiac function, and psychological function [7]. No UL established.
Japan (MHLW): Eligible for Foods with Function Claims. Recommended intake: 1.4 mg/day for adult males. Benfotiamine (fursultiamine) is available as OTC pharmaceutical.
South Korea (MFDS): Registered health functional food ingredient. Approved claims: energy metabolism and nervous system function.
8 US supplement products
58
on-market products containing Thiamine (NIH DSLD)
Brands carrying Thiamine (2)
Click a brand to see its Thiamine products.
9 Frequently paired with
10 Cite this page
Vancouver: Pkhakadze G. Thiamine — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Aug 15]. Available from: https://supplement.ge/ingredients/thiamine/
APA 7th: Pkhakadze, G. (2026). Thiamine — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/thiamine/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: February 2027
References: 7 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "Thiamine — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/thiamine/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG