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Oral or intravenous thiamine in the emergency department

Three Part Question

In [thiamine deficient patients without Wernickes encephalopathy] is [parental delivery of thiamine better than the oral route] at[achieving bioavailability without side effects]?

Clinical Scenario

A 56 year old male attends the emergency department with cellulitis in his left leg. He is unkempt and drinks heavily. The cellulitis can be treated as an out patient with oral antibiotics, but you suspect he is thiamine deficient as a result of chronic alcohol abuse. You are therefore about to prescibe an intravenous infusion of thiamine as you have always given it this way. This will comit you to an inpatient admission and beds are at a premium.You wonder whether there is any basis for your prescribing practice - perhaps oral thiamine would be just as effective.

Search Strategy

Medline 1966-03/04 using the Ovid interface.
[(exp thiamine OR OR (vitamin adj5 b1).af) AND (exp infusions, intravenous/ OR exp injections, intravenous OR OR exp infusions, parenteral OR AND (exp administration, oral OR OR exp tablets OR OR] LIMIT to human AND English Language.

Search Outcome

Altogether 25 papers found of which 2 were relevant to the three part question

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Tallaksen CME et al,
6 healthy volunteers IV v oral bolus 50mg dosesCrossover studyMean total increase in blood thiamine diphosphateIV mean 55.5 (sd 23.0)%
oral 1.8x baseline
Small numbers Inconsistencies in calculations as shown Statistical significance not assessed Reporting appears biased
Baines M et al,
25 healthy alcoholics 250 mg thiamine daily IM vs oralControlled trialThiamin diphosphate levels at 1 dayIncrease in both groups. Only statistically significant in IM group
Thiamin diphosphate levels at 5 daysStatistically significant and identicalincrease in both groups


Clearly concordance with treatment also has to be considered. This has not been considered at all in the papers found.

Clinical Bottom Line

Oral thiamine administration is as effective as parenteral administration after 5 days. In compliant alcoholics without encephalopathy oral administration is the route of choice.


  1. Tallaksen CME, Sande A, Bohmer T, et al. Kinetics of thiamin and thiamin esters in human blood, plasma and urine after 50mg intravenously or orally. Eur J Clin Pharmacol 1993;44:73-78.
  2. Baines M, Bligh JG, Madden JS Tissue thiamin levels of hospitalised alcoholics before and after oral or parenteral vitamins. Alcohol Alcohol 1988;(23)1:49-82.