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Thiamine Side Effects

The most commonly reported side effects of thiamine include off label use, nausea, and dyspnoea, based on 18,234 FDA adverse event reports from 2004 to 2025. 4.3% of reports found the drug to be ineffective.

Thiamine side effects

Percentages show how often each reaction appears relative to total reports for thiamine.

1
Off Label Use4.9%901
2
Nausea4.5%829
3
Drug Ineffective4.3%780
4
Dyspnoea4.3%778
5
Diarrhoea4.1%740
6
Flushing4.0%735
7
Pain3.8%696
8
Fatigue3.8%691
9
Confusional State3.3%597
10
Vomiting3.2%587
11
Malaise3.1%558
12
Headache2.9%535
13
Fall2.9%530
14
Condition Aggravated2.9%529
15
Dizziness2.9%527

These are voluntary reports and do not establish that thiamine caused these reactions.

Report severity

79.7%Serious14,540 reports
48.1%Hospitalizations8,779 reports
12.6%Fatal2,297 reports

Seriousness is determined by the reporter, not by OpenClaim.

Thiamine drug interactions

Other drugs that appear in adverse event reports alongside thiamine. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Adalimumab4.8%883
2
Niacin4.8%874
3
Acetaminophen4.4%810
4
Folic-acid4.1%742
5
Ascorbic-acid3.5%636
6
Riboflavin3.4%614
7
Omeprazole3.3%596
8
Pyridoxine2.8%511
9
Furosemide2.7%497
10
Prednisone2.7%495
11
Methotrexate2.7%485
12
Hydrocortisone2.6%482
13
Sertraline-hydrochloride2.5%459
14
Ergocalciferol2.5%453
15
Infliximab2.5%451

Taken alongside

1
Folic-acid40.2%7,327
2
Ergocalciferol33.1%6,041
3
Cyanocobalamin30.3%5,519
4
Ascorbic-acid29.8%5,428
5
Pyridoxine28.0%5,097
6
Riboflavin26.0%4,735
7
Biotin24.7%4,499
8
Vitamin-e24.0%4,368
9
Vitamin-a23.7%4,322
10
Dexpanthenol23.6%4,303
11
Niacinamide23.0%4,199
12
Acetaminophen21.7%3,952
13
Aspirin19.9%3,636
14
Omeprazole15.5%2,826
15
Furosemide13.0%2,370

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports thiamine side effects

42.9% of thiamine adverse event reports involve female patients and 49.7% involve male patients. The largest age group is adult at 61%. These figures reflect who reports side effects, not underlying risk.

Sex

Female42.9%
Male49.7%
Unknown7.5%

Age group

< 20.7%
2–110.7%
12–170.8%
18–6460.9%
65+36.9%

What is thiamine used for

Conditions and purposes for which patients were taking thiamine when the adverse event was reported.

Acute Kidney InjuryAdjuvant TherapyAdverse EventAgitationAlcohol AbuseAlcohol DetoxificationAlcohol PoisoningAlcohol ProblemAlcohol UseAlcohol Use DisorderAlcohol Withdrawal SyndromeAlcoholicAlcoholic Liver DiseaseAlcoholismAlopecia

Showing 15 of 409 indications

Thiamine brand names and reporting trend

Thiamine is sold under brand names including M.v.i.-12 Lyophilized, M.v.i.-12 Adult.

Brand names

M.v.i.-12 Lyophilized15,257
M.v.i.-12 Adult278

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking thiamine with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.